ETL41 Manual En

Utility Communication Systems

5HYN589126-TA

PLC EQUIPMENT ETL41/42/43/44 OPERATING INSTRUCTIONS 5HYN589126-TA

Edition 04 September 2007

Utility Communication Systems

5HYN589126-TA

Single Sideband Power Line Carrier Equipment Types ETL41/42/43/44 for HV Transmission Lines OPERATING INSTRUCTIONS All rights, including applications for patent and registration of other industrial property rights, are reserved. Without the written authority of ABB LTD., it is neither permitted to reproduce this document, its appendices or any part thereof either electronically or mechanically (including photocopying and microfilming), nor divulge its contents or make them accessible to third parties. Liability The data contained herein purport solely to describe the product and are not a warranty of performance or characteristic. It is with the best interest of our customers in mind that ABB LTD., constantly strives to improve its products in accordance with advances in technology. This may lead, however, to minor dis-crepancies between the product supplied and its "Technical Description" or "Instructions for Installation and Operation". This document has been carefully reviewed. Should in spite of this errors or omissions be discovered, the purchaser is kindly requested to notify ABB LTD., at his earliest convenience.

ESD PROTECTION The modules in this equipment contain CMOS devices, which can be damaged by electrostatic discharges. Appropriate measures must be taken before unpacking modules or withdrawing them from equipment racks. Essential precautions to prevent ESD damage when handling or working on modules are grounding straps for technical personnel and the provision of anti-static work benches. Modules may only be shipped either in their original packing or installed in equipment racks.

Utility Communication Systems Table of contents ETL41/42/43/44

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TABLE OF CONTENTS

PART I DESCRIPTION OF THE EQUIPMENT 1-1

1. GENERAL 1-1

1.1 Introduction 1-1 1.2 Purpose and scope of these operating instructions 1-2

2. TYPE DESIGNATIONS AND VERSIONS 2-1

2.1 Type designations 2-1 2.2 Alternative versions 2-1 2.2.1 Built-in data modem NSK 5 for telecontrol 2-3 2.2.2 AF repeater equipment, transit filter 2-5 2.2.3 Telephony equipment 2-6 2.2.4 Built-in teleprotection device NSD 50 2-8 2.2.5 Pilot channel functions and versions 2-8 2.2.6 Supervision and alarm facilities 2-9 2.2.6.1 Plug-out supervision 2-12 2.2.6.2 Alarm code display on P4LA 2-14 2.2.6.3 Examples of alarms 2-17 2.2.7 Main RF components 2-19 2.2.8 Two-channel operation 2-20 2.2.9 Three and four-channel operation 2-20 2.2.10 Auxiliary supply 2-22 2.2.11 Testing facilities 2-23

3. MECHANICAL DESIGN 3-1

3.1 Construction 3-1 3.2 Units fitted 3-1 3.3 Internal wiring 3-1 3.4 External connections 3-1

4. TECHNICAL DATA 4-1

4.1 System data 4-1 4.2 Transmitter data 4-8 4.3 Receiver data 4-9 4.4 AF interfaces 4-10 4.4.1 Telephony interfaces 4-10 4.4.2 Telecontrol interfaces 4-14 4.5 Testing facilities 4-21 4.6 Auxiliary supplies 4-22 4.7 Insulation tests and electromagnetic compatibility 4-23 4.8 Physical dimensions and weights 4-26


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5. PRINCIPLE OF OPERATION 5-1

5.1 Modulation scheme 5-1 5.2 Carrier frequency section 5-4 5.2.1 Transmitter 5-4 5.2.2 Receiver 5-7 5.3 Carrier synthesizer (local oscillator) P4LG 5-10 5.4 40 W power amplifier section 5-11 5.5 Pilot and supervision unit P4LA 5-13 5.5.1 Pilot channel 5-13 5.5.2 Supervision section 5-14 5.6 Synchronising receivers 5-21 5.7 Telephony interfaces 5-23 5.7.1 2/4-wire PAX interface O4LC 5-23 5.7.2 4-wire PAX interface O4LB 5-25 5.8 Telecontrol interfaces 5-27 5.8.1 Telecontrol interface O4LA 5-27 5.8.2 Digital transit filter E1LA 5-28 5.9 NSK 5 operation 5-30 5.10 Teleprotection device Type NSD 50 5-34 5.11 AF bus design 5-38 5.12 Two-channel PLC equipment Type ETL42 5-39 5.13 Three and four-channel PLC equipment Types ETL43/44 5-41 5.14 Auxiliary supply 5-43

TEIL II APPLICATION, PROGRAMMING AND TESTING 6-1

6. OPERATING MODES 6-1

6.1 Multi-purpose mode (main operating mode) 6-1 6.2 Single-purpose mode 6-2 6.3 Multi-channel mode 6-2

7. ALTERNATIVE VERSIONS 7-1

8. SETTING AND PROGRAMMING ALTERNATIVE VERSIONS 8-1

9. SYSTEM LEVEL, EQUIPMENT SETTINGS 9-1

9.1 Basic terms 9-1 9.2 Allocating powers to speech and data channels 9-3 9.3 Determining the transmission levels for ETL41/42 9-4 9.4 Determining the transmission levels for ETL43/44 9-8 9.5 Reduced O/P power 9-13 9.6 Signal boosting for teleprotection channels 9-14


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PART III INSTALLATION, COMMISSIONING, OPERATION AND MAINTENANCE 10-1

10. INSTALLATION 10-1

10.1 Instructions and recommendations 10-1 10.2 Mechanical inspection 10-1 10.3 Equipment room 10-1 10.4 Erecting the cubicle 10-2 10.5 External connections 10-2

11. COMMISSIONING 11-1

11.1 Checking the line of communication 11-1 11.1.1 Return loss 11-1 11.1.2 Line attenuation 11-6 11.2 Commissioning the ETL41/42 11-7 11.2.1 Preliminary tests and checks 11-7 11.2.2 Tests according to the commissioning instructions 11-8 11.2.3 Local loop test and dummy load P3LK 11-9 11.2.4 Remote loop test under operational conditions 11-9 11.2.5 Equalizing channel distortion 11-9 11.3 Programming and tuning the RF channel 11-10

12. OPERATION 12-1

13. MAINTENANCE 13-1

PART IV APPENDICIES A1-1

A.1 ALTERNATIVE VERSIONS A1-1

ETL41 Front view A1-2 Rear view A1-3 Module arrangement A1-4 Mechanical dimensions 5HYN589127-AA A1-5 Cabinet layout 5HYN589246-AA A1-6




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Dimensioned drawing of cubicle 5HYN589131-AA A1-22 Type E35C

ETL41/42/43/44 List of modules A1-23

A.2 BLOCK DIAGRAMS A2-1

ETL41/42/43/44 AF options Telecontrol interface O4LA 5HYN589043-CA A2-2 Four-wire telephony interface O4LB 5HYN589133-CA A2-3 Two and four-wire telephony interface O4LC 5HYN589134-CA A2-4

Universal telephony unit O4LD 5HYN589244-CA A2-5 ETL42/43/44 Channel 2 converter section 5HYN589135-CA A2-6 ETL41/42/43/44 Channel 1 converter section 5HYN589136-CA A2-7 ETL41/42/43/44 40 W power amplifier 5HYN589137-CA A2-8 ETL41/42/43/44 40 W power supply 5HYN589138-CA A2-9

A.3 INTERNAL WIRING A3-1

ETL41/42/43/44 Channel rack P7LB 5HYN589139-CA A3-1

A.4 INTERSTAGE WIRING AND EXTERNAL CONNECTIONS A4-1

Interstage wiring and external connections 5HYN589132-WA A4-2 L.H.Side plate P7LA 5HYN693002 A4-3 Side bracket P7LB 5HYN217005 A4-4

A.5 NEW INTRODUCTION A5-1

A.5.1 ETL Test Meter N3NL A5-1 A.5.2 Remote subscriber application with PAX_SUB and 2 WINT A5-2 A.5.2.1 PAX subscriber A5-3 A.5.2.2 2 WINT Interface A5-5 A.5.3. ETL Test Tone Interface TTX A5-9 A.5.4 Universal Speech Interface Circuit (USIC) A5-10


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LIST OF FIGURES Fig. 2.1 Frequency allocation in the AF band 2-2 Fig. 2.2 Plug-out supervision for channels 1 to 4 2-13 Fig. 4.1 Group delay distortion, Bandpass 2160 - 3600 Hz 4-15 Fig. 4.2 Group delay distortion, Bandpass 2160 - 3480 Hz 4-15 Fig. 4.3 Group delay distortion, Bandpass 2400 - 3600 Hz 4-16 Fig. 4.4 Group delay distortion, Bandpass 2400 - 3480 Hz 4-16 Fig. 4.5 Group delay distortion, Bandpass 2520 - 3600 Hz 4-16 Fig. 4.6 Group delay distortion, Bandpass 2520 - 3480 Hz 4-17 Fig. 4.7 Group delay distortion, Lowpass 3600 Hz 4-17 Fig. 4.8 Group delay distortion, Lowpass 3480 Hz 4-17 Fig. 4.9 Group delay distortion, Highpass 2520 Hz 4-18 Fig. 4.10 Group delay distortion, Highpass 2760 Hz 4-18 Fig. 5.1 Modulation scheme for ETL41/42 5-2 Fig. 5.2 Modulation scheme for ETL43/44 5-3 Fig. 5.3 Carrier scheme and receiver synchronisation 5-21 Fig. 5.4 Programmable transit filter E1LA Programming the bandpass range in steps of 60 Hz 5-28 Fig. 5.5 Block diagram of the digital transit filter E1LA 5-29 Fig. 5.6 Interconnections between the NSK 5 modem G4AE and ETL 5-31 Fig. 5.7 Front view of modem Type G4AE 5-33 Fig. 5.8 Front view of the teleprotection device Type NSD 50 5-35 Fig. 5.9 Interconnections between ETL and NSD 50 5-36 Fig. 5.10 AF bus layout 5-38 Fig. 11.1 Instruments and test circuit for measuring return loss 11-3 Fig. 11.2 Test circuit for measuring return loss under practical conditions with the transmission line as load 11-3 Fig. 11.3 Typical return loss characteristic under practical conditions with the transmission line as load 11-4 Fig. 11.4 Typical return loss characteristic at rated load 11-4 Fig. 11.5 Test circuit using a dummy load for measuring return loss in the case of single-phase coupling 11-5 Fig. 11.6 Test circuit using a dummy load for measuring return loss in the case of phase-to-phase coupling 11-5 Fig. 11.7 Test circuit for measuring line attenuation in the case of single-phase coupling 11-6 Fig. 11.8 Test circuit for measuring line attenuation in the case of phase-to-phase coupling 11-7


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LIST OF TABLES Table 2.1 Telecontrol I/P's and O/P's available on O4LA 2-4 Table 2.2 AF I/P's and O/P's available on P4LB 2-4 Table 2.3 Telephony I/P's and O/P's 2-7 Table 2.4 Auxiliary supply supervision 2-9 Table 2.5 Transmitter/receiver supervision 2-10 Table 2.6 Supplementary alarm and WARNING functions 2-11 Table 2.7 Alarm pick-up and reset times 2-12 Table 2.8 Table of alarm codes displayed on P4LA (pilot and supervision unit) 2-16 Table 2.9 Typical cases of alarm 2-18 Table 2.10 Allocation of PSU's and DC/DC converters 2-22 Table 5.1 Blocking control alarm logic 5-18 Table 9.1 Allocation of powers to speech and VFT channels 9-3 Table 9.2 Channel loading and transmitter level 9-12

Utility Communication Systems General ETL41/42/43/44

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PART I DESCRIPTION OF EQUIPMENT

1. GENERAL

Because of their low attenuation in the carrier frequency range between 20 and 500 kHz, HV transmission lines are a good means of communicating information over medium to long distances (20 to 100 km, re-spectively 100 to 500 km). The maximum range of a PLC communications channel operating at the lower end of the carrier frequency range up to about 80 kHz can as much in special cases as about 800 km, whi

ch cannot be even remotely matched by other means of communication at the disposal of power com-panies (cables, pilot wires, normal radio or point-to-point radio) without repeaters or repeater stations.

By installing appropriate coupling devices and line traps in power stations and substations communications channels can be provided, which exhibit

- extremely high mechanical rigidity and high reliability of the interconnecting lines - lines and terminal equipment, which belong to and is permanently under the control of the power utility - low, relatively constant attenuation and moderate long-duration noise level (corona) under normal atmo-

spheric conditions - high short-duration noise level (bursts) due to the operation of circuit-breakers and load-break isolators

The system includes means to combat burst noise, which virtually exclude any possibility of false signals or tripping; thus the reliability of PLC channels is roughly equivalent to that of the terminal equipment. In spite of the additional cost represented by the coupling devices and line traps, especially at EHV levels, the overall cost of a PLC communications system is relatively low compared with other techniques and the cost relation becomes even more favourable the longer the distance. These are the two main reasons why many power utilities prefer PLC for power system communication.

1.1 Introduction

Power line carrier is used in almost all the countries of the world to transfer information via HV transmission lines and has become an important instrument for the management and safety of electrical power systems. Of the possible PLC techniques, single sideband modulation with a 4 kHz spacing to make the best use of the available frequency bands and permitted transmitting powers, and the European practice, mainly for reasons of cost, of multiple use of PLC channels for speech, data and protection signals have become widely established. International recommendations for the characteristics of line traps, PLC coupling devices and single sideband PLC equipment (IEC Publications 353, 358, 481 and 495) and also for the design of PLC links (IEC Publication 663) have come into force. All the relevant CCIR and CCITT recommendations in IEC Publication 495 were also taken into account, in order to ensure reliable coupling of channels at the AF interfaces in power system control centres, power stations and transformer stations between power utility PLC, normal radio and point-to-point radio and also leased back-up links.

Utility Communication Systems General ETL41/42/43/44

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1.2 Purpose and scope of these operating instructions

This document is intended as a guide for the user and commissioning engineers during commissioning and the subsequent operation and maintenance of ETL PLC equipment.

Part I is devoted to describing the equipment and comprises the Sections "Type designations and versions", "Mechanical design", "Technical data" and "Principle of operation".

Part II "Applications, programming and testing" describes the possible operating modes and equipment configurations. Another section deals with the setting and programming of the different versions. The last section is concerned with system operating level and adjusting the operating level of the equipment.

Part III contains details related to installation, commissioning, operation and maintenance.

Part IV "Appendicies" is a collection of pictures, dimensioned drawings and block diagrams.

The programming, tuning and testing instructions are contained in the supplementary document 5HYN589144-TA.

Utility Communication Systems Type designations and alternative versions ETL41/42/43/44

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2. TYPE DESIGNATIONS AND ALTERNATIVE VERSIONS

2.1 Type designations

The different types of the ETL series of units vary in transmitting power and the number of channels. The 40 W class includes the following types:

ETL41 SSB unit, one channel, RF O/P power 40 W PEP (peak envelope power)

ETL42 SSB unit, two channels, RF O/P power 40 W PEP

ETL43 SSB unit, three channels, RF O/P power 40 W PEP

ETL44 SSB unit, four channels, RF O/P power 40 W PEP

2.2 Alternative versions

Each of the ETL units listed above is designed for multi-purpose operation. The available AF band can be used as required. A large number of operating modes can be achieved with the following AF interfaces. A typical allocation of frequencies in the AF band is given in Fig. 2.1. Using the standard pilot channel, the fol-lowing alternatives are possible:

Only telecontrol: 300 Hz - 3600 Hz

Only speech: 300 Hz - 3400 Hz

Speech and telecontrol:

Speech band Telecontrol band 300 - 2000 Hz 2160 Hz - 3600 Hz 300 - 2200 Hz 2400 Hz - 3600 Hz 300 - 2400 Hz 2640 Hz - 3600 Hz


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Fig. 2.1 Frequency allocation in the AF band


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If one of the optional pilot channels is used, 3850 Hz of the AF band are available. In this case the pilot oc-cupies a bandwidth corresponding to a 100 Bd channel within the AF band.

2.2.1 Built-in data modem NSK 5 for telecontrol

The telecontrol interface O4LA and the built-in data modem NSK 5 make the system extremely versatile for the transfer of data. Both modules can be used either on their own or in combination. They enable data transfer terminal equipment to be directly connected via the modem's serial interface and also speech fre-quency modem signals to be connected via the telecontrol interface.

Telecontrol interfaces Types O4LA and P4LB

The O4LA unit facilitates the connection of external modems and voice frequency telegraph (VFT) chan-nels. At the transmitter end there are three balanced DC isolated I/P's, which can be individually connected either to the disconnectable TX AF-D bus or the non-disconnectable TX AF-ND bus by appropriately positioning plug-in jumpers. Similarly at the receiver end, there are three balanced DC isolated O/P's for the AF signals, which can be individually programmed for one of the following operating modes with the aid of plug-in jumpers:

- broadband 300 Hz to 3850 Hz (standard) - low-pass 300 Hz to 3600 Hz (optional on P4LB) - transit filter E1LA selectable frequency band (optional on O4LA)

The DC isolated auxiliary I/P's and O/P's (AUX. AF INPUT and AUX. AF OUTPUT) are also available on the AF multiplexer P4LB for connecting an external teleprotection unit or for broadband transit of AF signals. The power of teleprotection signals applied to the AUX. AF INPUT can be boosted.

The signal available at AUX. AF OUTPUT is an AF with a standard upper frequency limit of 3.85 kHz or an optional frequency limit of 3.6 kHz (use of the low-pass filter on P4LB to suppress the standard pilot signal when repeating transit signals).

Tables 2.1 and 2.2 give a summary of the I/P's and O/P's for telecontrol.


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O4LA

I/P’s Impedance Setting range Remarks

INPUT 1, 2, 3 600 Ohm -20 to +10 dBr Steps of 0.25 dB All I/P's can be programmed to be disconnectable or non-disconnectable. I/P 2 can be programmed as transit filter I/P or as broadband I/P

O/P's

OUTPUT 1, 2, 3 600 Ohm -20 to +10 dBr Steps of 0.25 dB All O/P's can be programmed as transit filter O/P or as broadband O/P

Note: The number of telecontrol I/P's and O/P's can be increased by connecting further O4LA modules

in parallel. Table 2.1 Telecontrol I/P's and O/P's available on O4LA P4LB

I/P or O/P Impedance Setting range Remarks

-10 dBr standard AUX. AF INPUT 600 Ohm (-20 to +0 dBr) Power boosting settings 0, 5, 7, 9 dB

AUX. AF OUTPUT 600 Ohm -10 dBr standard standard 3.85 kHz (-3.5 dBr) option 3.6 kHz

Table 2.2 AF I/P's and O/P's available on P4LB


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Data modem NSK 5

As is the case with the other AF interface boards, the programmable AF modem type NSK 5 can be directly inserted into the channel rack type P7LB. This possibility has a positive influence on the cost of setting up telecontrol networks, because it avoids the need of separate equipment racks and auxiliary supplies. The amount of equipment rack space available for the NSK 5 modem depends on which ETL version in use (see Section 7 "Alternative versions"). The channel rack type P7LB has accommodation for a maximum of 5 NSK 5 modems (unit Type G4AE), but in this case the DC/DC converter B4LB is required.

The main features of the G4AE modem for use with ETL equipment (further details are to be found in Operating instructions NSK 5 5HYN589143-TA) are as follows:

Fully programmable VFT channel with DIL switch and jumper settings for baud rate, transmitting and re-ceiving frequencies and transmitter level.

- All channels and baud rates according to CCITT R.35, R.37, R.38A and R.38B can be programmed.

The following operating modes are also possible:

- maximum three 600 Bd channels. - a 1200 Bd channel suitable for use above 2000 Hz for speech or superimposed on

VFT channels - a 1200 Bd channel according to CCITT V.23 - a 2400 Bd channel

2.2.2 AF repeater equipment, transit filter

As mentioned in Section 2.2.1, the transit filter for selectively relaying one or several data channels can be inserted into any of the three telecontrol O/P's or telecontrol I/P 2. Thus only selected channels are relayed to the next PLC section in intermediate stations, which makes the bandwidth of locally terminating channels available for other purposes on the next section. It is frequently the case in stations at nodes in the power system, that data channels have to be transmitted in a number of directions. For this purpose there is the AF bus, which enables several telecontrol interfaces equipped with transit filters to be operated in parallel.

With the digital transit filter E1LA all the bandpass filters, which lie in the AF band from 360 Hz to 3720 Hz, can be programmed in steps of 60 Hz. There are also ten special group delay equalized filters available. Other filters for specific applications can be fitted subsequently as required.


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2.2.3 Telephony equipment

Three telephony interfaces for the following operating modes are provided:

- 4-wire PAX-PAX O4LB - 2/4-wire PAX-PAX O4LC - remote subscriber O4LD - 4-wire service telephone standard equipment

Plug-in jumpers enable the bandwidth of all the telephony interfaces to be set to one of the following:

- 300 - 2000 Hz - 300 - 2200 Hz - 300 - 2400 Hz

The upper limits of these bandwidths can be programmed in steps of 200 Hz to other values in a range from 1800 Hz to 3600 Hz.

4-wire PAX mode O4LB

Unit Type O4LB is the interface used for connecting four-wire speech signals and the corresponding signalling criteria to exchange equipment. All the functional blocks for processing transmitter and receiver speech signals and the associated signal logic are contained in this unit. The circuits required for a four-wire service telephone are also provided.

The signalling and control logic signals are transferred via opto-coupler interfaces. These can be DC isolated by using an optionally available DC/DC converter. The dialling signals for transmission are applied to I/P "SIGNALLING M" and those received are passed on to the PAX via O/P "SIGNALLING E". Provision is made by appropriate programming for inverting the dialing pulses. The LED "BUSY" indicates that the "M" and/or "E" lines are active.

The control signal "SPEECH CONTROL" generated by the exchange equipment switches the system from local to transit operation.

The receiver channel is blocked should the signal quality or strength become too low, or a tripping signal from the NSD 50 be present.

2/4-wire PAX mode O4LC

With the exception of an additional two-wire port and a control I/P marked "HYBRID", the functions of the Type O4LC interface are identical to those of Type O4LB.

Table 2.3 summarises the telephony I/P's and O/P's.


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Function Level/Level range Remarks

4-wire PAX interface O4LB 4-wire I/P 600 Ohm -3.5 dBr standard -20 up to +10 dBr adjustable in steps of 0.25 dB 4-wire O/P 600 Ohm -3.5 dBr standard -20 up to +10 dBr adjustable in steps of 0.25 dB M-SIGNALLING "MARK" 0 V external contact closed "SPACE" -12.5 V external contact open E-SIGNALLING "MARK" opto-coupler on O4LB "ON" "SPACE" "OFF" SPEECH CONTROL "ON" 0 V external contact closed compandor off "OFF" -12.5 V external contact open compandor on PAX BLOCKING potentially-free contact on O4LB "ON" closed "OFF" open

2/4-wire PAX interface O4LC 2-wire I/P 600 Ohm 0 dBr standard -16 to +6 dBr adjustable in steps of 0.25 dB 2-wire O/P 600 Ohm -7 dBr standard -16 to +6 dBr adjustable in steps of 0.25 dB 4-wire I/P 600 Ohm -3.5 dBr standard -20 to +10 dBr adjustable in steps of 0.25 dB 4-wire O/P 600 Ohm -3.5 dBr standard -20 to +10 dBr adjustable in steps of 0.25 dB M-SIGNALLING "MARK" 0 V external contact closed "SPACE" -12.5 V external contact open E-SIGNALLING "MARK" opto-coupler on O4LC "ON" "SPACE" "OFF" HYBRID "ON" 0 V external contact closed, hybrid in "OFF" -12.5 V external contact open hybrid out SPEECH CONTROL "ON" 0 V external contact closed, 4-wire level compandor off "OFF" -12.5 V external contact open, 2-wire level compandor on PAX BLOCKING potentially-free contact on O4LC "ON" closed "OFF" open

Table 2.3 Telephony I/P’ and O/P’s


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2.2.4 Built-in teleprotection device NSD 50

Type ETL PLC equipment has an optional built-in teleprotection unit Type NSD 50 for the transfer of protection transfertripping signals. The NSD 50 itself comprises a maximum of three units, which are inserted into spaces prepared for them in the PLC equipment (see Fig. 5.7 and Appendix A.1-4).

The smallest version of the NSD 50 has two units and is able to transfer two independent tripping signals. Two tripping channels usually suffice for the protection of a transmission line. The scheme can be extended to four tripping channels by simply inserting a further relay interface. There are then two groups of signals each comprising two permissive and two direct transfer tripping signal, the latter having priority. For exam-ple, with the maximum complement of four transfer tripping signals per PLC channel and two PLC channels, first and second main protections can be provided for a double circuit line.

Normally the NSD 50 jointly uses the PLC pilot of the ETL. The receiver in the opposite station continuously monitors the pilot and gives alarm, if signal quality should fall below a permissible level.

In the event of a fault on the protected line, the NSD 50 interrupts the pilot and transmits a corresponding tripping signal in the speech band of the PLC equipment. Accordingly, control signals from the NSD 50 also interrupt the transmission of speech and any super audio data channels, which may permissibly be switched off, and also boost the transmitter power briefly to its maximum.

Providing the NSD 50 at the receiving end detects that the pilot signal has disappeared at the same time as a tripping signal is being received, the tripping signal is passed on to the corresponding O/P.

By making use of the pilot signal generated by the PLC equipment and the transmission of tripping signals in the speech band, the NSD 50 requires no additional PLC bandwidth.

2.2.5 Pilot channel functions and versions

The ETL pilot channel is extremely important and performs the following functions:

- synchronises the receiver - determines the gain of the receiver (AGC) - acts as guard signal for the teleprotection unit NSD 50 - serves as telephony signalling channel - serves as reference signal for monitoring signal quality at the receiver (min. signal

strength, SNR) - initialises the remote loop test mode

The functions of the pilot signal are described in detail in Section 5.5 "Pilot and supervision unit P4LA".

The following alternatives are provided for the pilot:

Nominal frequency: 3780 Hz ±30 Hz

Alternative frequencies: 2160 Hz ±30 Hz 2640 Hz ±30 Hz 3360 Hz ±30 Hz 3600 Hz ±30 Hz

Note: The higher of the two characteristic frequencies is referred to as SPACE and the lower as MARK.


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2.2.6 Supervision and alarm facilities

All ETL alarms and operating statuses are marshalled on the pilot and supervision unit P4LA (see Section 5.5.2). Should one or several monitored parameters indicate an alarm condition, the corresponding LED lights on the P4LA, respectively on the unit concerned. Precautions are initiated inside the equipment and five auxiliary relay contacts are provided for giving alarm. Fault-finding is made simpler by the display of a fault code on the pilot and supervision unit P4LA. This is generated by briefly pressing the test tone button. The fault code gives additional information relating to the cause of the failure (see Table 2.8 "Alarm codes"). A WARNING is generated instead of an alarm for certain operating statuses and low priority failures. Tables 2.4, 2.5 and 2.6 list the alarm conditions, the related displays, the internal response by the PLC equipment and the external alarm signals generated. The pick-up and reset times of alarm signals are given in Table 2.7.

Alarm condition LED signal Fault code Internal alarm External alarm on the front plate LED signal response signal on P4LA by P4LA by P4LA

AUXILIARY SUPPLY Failure on B5LA/C B5LA/C All alarm relays reset LED "POWER" extinguished B4LA LED "ON" extinguished P4LA LED "SUP" extinguished Failure on B4LA B4LA All alarm relays reset LED "ON" extinguished P4LA LED "SUP" extinguished DC/DC converter failure B4LB (redundant supply units) LED "ON" extinguished on B4LB on the module concerned P4LA LED WARNING H1 WARNING 1 contact for CABINET ALARM lit 1 C/O contact for WARNING or BURST/SNR* Undervoltage on B4LA B4LA LED "ON" extinguished, LED "UB<" lit P4LA All alarm relays reset LED "SUP" extinguished ±12 V, +5 V output voltages P4LA All alarm relays reset out of tolerance LED "SUP" extinguished Overload on B4LA B4LA Corresponding "OVERLOAD" LED's lit

* Optional

Table 2.4 Auxiliary supply supervision


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Alarm condition LED signal Fault code Internal alarm External alarm on the frontplate LED signal response signal on P4LA by P4LA by P4LA

TRANSMITTER RF transmitter P3LA E O/P amp. on P1LA 1 C/O con. TX ALARM* current too low "TX-ALARM" disconnected from 1 C/O con. COMMON ALARM* or supply ≤ 35 V TX filter E5LA/B 1 contact CABINET ALARM Setting: P4LA Unit P4LA ETL41 TX O/P ≤ pilot - 6 dB "TX" PAX BLOCKING ETL42 TX O/P ≤ pilot - 3 dB TXB ETL43 TX O/P ≤ pilot - 1.5 dB ETL44 TX O/P ≤ pilot - 0 dB Unit P4LA AF pilot failure "TX" E TX PILOT FAIL Processed by NSD 50

RECEIVER Signal strength too low. P4LA E Unit P4LA 1 C/O con. RX ALARM* Pilot level 2 - 5 dB "RX" PAX BLOCKING 1 C/O con. COMMON ALARM* lower than normal. SLOW MUTE 1 contact CABINET ALARM FAST MUTE 1 C/O con. BURST SNR SOF High noise level P4LA E Unit P4LA 1 C/O con. RX ALARM* Possible SNR settings "SNR" PAX BLOCKING 1 C/O con. COMMON ALARM* of 9 or 15 dB SLOW MUTE 1 contact CABINET ALARM FAST MUTE 1 C/O con. BURST SNR* SB Impulse noise interference FAST MUTE 1 C/O con. BURST SNR* Typical detector response time 10 ms

* Optional

Table 2.5 Transmitter/receiver supervision


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Alarm condition LED signal Fault code Internal alarm External alarm on the frontplate LED signal response signal on P4LA by P4LA by P4LA

PLUG-OUT supervision Depends on H7 TXB All alarm relays reset Unit of basic equipment missing PCB TRY not plugged in SLOW MUTE (excl. AF options) FAST MUTE SOF PAX BLOCKNG

COMMON ALARM “COMMON” Depends Depends on fault 2 C/O contacts At least one alarm on fault See Table 5.1 COMMON ALARM* condition in Table For Microprocessor or See Table 5.1 of Section 5.5.2 signal processor failure 2.8 fulfilled. Logic on P4LA for ETL system and “P4LA” general alarms from certain AF units, NSD50 and NSK5. Other signals depend on type of fault.

WARNING "WARNING" Depends Depends on fault 1 contact CABINET ALARM (low priority alarms) on fault or or operating 1 C/O cont. WARNING or At least one alarm op. status. status. BURST/SNR* condition in Table See Table See Table 5.1 5.1 of Section 5.5.2 2.8 fulfilled. Logic on P4LA for low priority ETL and certain AF unit alarms. Operating statuses causing WARNING: LOCAL LOOP L5 (dummy load inserted) LTC/RTC: (remote loop mode) One DC/DC conv. failed of redund. P4LB aux. sup. Recoverable data error with digital transit filter E1LA or signal processor P4LA

CABINET ALARM Depends on Depends Depends on 1 contact CABINET ALARM Accompanies COMMON on fault. fault. fault. ALARM or WARNING See Table See Table 5.1 2.8

* Optional

Table 2.6 Supplementary alarm and WARNING functions


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Alarm conditions Aux. alarm relays Pick-up time (sec.) Reset time (sec.)

Aux. PSU alarm K1, K2*, K3*, K4* 2 0

TX ALARM K1, K2* 2 or 2 or 10 10

RX ALARM K1, K3* 2, 5, 10, 15 2, 5, 10, 15 (RXL or SNR)

AF COMMON K1, K2*,K3* 1 2

WARNING K1, K4* 1 1

Subsequent alarms Aux. alarm relays Pick-up time (sec.) Reset time (sec.)

COMMON ALARM K2*, K3* 2 or 10 2 or 10

CABINET ALARM K1 see above see above

* Optional Table 2.7 Alarm pick-up and reset times

2.2.6.1 Plug-out supervision

ETL PLC equipment includes a supervision facility, which supervises that all the units belonging to the basic equipment are properly inserted. Should one of the supervised units be missing, a COMMON (general) and a CABINET alarm are initiated by P4LA (pilot and supervision unit). A TX or an RX alarm may also be acti-vated and signalled by a LED, depending on the kind of fault. Alarm code H7 is displayed on P4LA, if the test tone button is briefly pressed. The operating principle of the missing unit supervision facility can be seen from Fig. 2.2.

The PLUG OUT 1 criteria supervises the common RF hybrid and the basic units of the various channels.

The criteria PLUG OUT 12 and PLUG OUT 22 supervise those units, which perform common functions for channels 1 and 2, respectively 3 and 4 and their signals are interlinked by PLUG OUT 1 OR in the P4LI units of channels 2 and 4.

This enables the following to be distinguished:

Missing RF hybrid P3LA/B*: All channels give alarm.

One of the P4LB or P4LC units missing: Corresponding channel gives alarm.

One of the P4LD/E/F/G units missing: Corresponding channels 1 and 3 and also channels 2 and 4 give alarm.

P4LI units or channel link V9LK missing: Channels 2 and 4 give alarm.

* Optional


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Fig. 2.2 Plug-out supervision for channels 1 to 4


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2.2.6.2 Alarm code display on P4LA

Whenever an alarm is activated on the ETL equipment, as indicated by one of the alarm LED's, additional information regarding the cause of the problem can be obtained by displaying the related alarm code (instead of the AGC display). This is achieved by briefly pressing the test tone button.

Table 2.8 lists the fault codes, which can be viewed on the display on the front of P4LA.

Alarm signals ensue from the evaluation of the following I/P's:

AGC BLOCKING: activated when NSD 50 is receiving a signal or the AGC blocking switch is set at the rear of NSD 50.

PILOT SWITCH: blocks the TX ALARM signal whilst NSD 50 is trans-mitting a tripping signal and also during the NSD 50 loop test and is activated when the pilot switch is set at the rear of NSD 50.

LOCAL LOOP: activated when the ETL equipment is set to local TX/RX loop, i.e. when the dummy load is plugged in.

PLUG-OUT 1: activated when one of the units of the basic ETL equipment is not plugged in.

DSPW: activated for a software error in the digital signal pro-cessor (DSP).

WARNING: low priority alarm initiated by certain ETL units (e.g. digital transit filter E1LA, DC/DC converter failure in the redundant auxiliary supply unit).

AF COMMON: general alarm initiated by certain ETL units (transit fil-ter E1LA) and by NSD 50 or NSK 5.

TX, RX, SNR transmitter/receiver alarm

Significance of displayed fault codes:

A fault code is displayed by briefly pressing the test tone button.

"0E" = no alarms active.

"E" = Rx, Tx or SNR alarms active.

"FE" = 5 I/P's are active. The AGC blocking and pilot switches are in their normal positions (OFF).

"P" = The pilot switch at the rear of the unit is set (ON).


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"A" = AGC blocking switch at the rear of the unit is set (ON).

"PA" = Both Pilot and AGC blocking switches at the rear of the unit are set (ON). When the pilot switch and / or AGC blocking switch are set on the P7LB back plane PCB, the WARNING LED lights and the auxiliary alarm relay K1 (CABINET ALARM) resets after T = 4 sec.

"H0".."H9" = combinations according to Table 2.8 "Table of alarm codes"

"L0".."L9" = combinations according to Table 2.8 "Table of alarm codes"

"P0".."P9" = combinations according to Table 2.8 "Table of alarm codes"


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I/P's supervised on unit P4LA

Fault AGC Pilot Local Plug- Warning Warning AF common code blocking jumper loop out 1 (P4LA, DSPW)

0E 0 0 0 0 0 0 0 E 0 0 0 0 0 0 0

FE 0 0 1 1 1 1 1 P 0 1 x x x x x A 1 0 x x x x x PA 1 1 x x x x x

H0 0 0 0 0 0 0 1 H1 0 0 0 0 0 1 0 H2 0 0 0 0 0 1 1 H3 0 0 0 0 1 0 0 H4 0 0 0 0 1 0 1 H5 0 0 0 0 1 1 0 H6 0 0 0 0 1 1 1 H7 0 0 0 1 0 0 0 H8 0 0 0 1 0 0 1 H9 0 0 0 1 0 1 0 L0 0 0 0 1 0 1 1 L1 0 0 0 1 1 0 0 L2 0 0 0 1 1 0 1 L3 0 0 0 1 1 1 0 L4 0 0 0 1 1 1 1 L5 0 0 1 0 0 0 0 L6 0 0 1 0 0 0 1 L7 0 0 1 0 0 1 0 L8 0 0 1 0 0 1 1 L9 0 0 1 0 1 0 0 P0 0 0 1 0 1 0 1 P1 0 0 1 0 1 1 0 P2 0 0 1 0 1 1 1 P3 0 0 1 1 0 0 0 P4 0 0 1 1 0 0 1 P5 0 0 1 1 0 1 0 P6 0 0 1 1 0 1 1 P7 0 0 1 1 1 0 0 P8 0 0 1 1 1 0 1 P9 0 0 1 1 1 1 0

Table 2.8 Table of alarm codes displayed on P4LA (pilot and supervision unit) "1"===> Alarm active. "0"===> Alarm inactive. "x"===> any state


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2.2.6.3 Examples of alarms

Table 2.9 summarises the possible causes of faults, operating statuses and their influence on the display and external signalling of alarms.

Fault/operating status Alarm displayed/signalled Normal operation LED SUPPLY (P4LA) Alarm code: OE (no fault) PCB of the basic equipment missing: ALARM CODE: H7 (PLUG-OUT) P4LB / P4LC / P4LD/E / P4LF / P4LG / P3LA Further alarms depending on the function of the PCB PCB P4LF missing or not properly inserted. TX ALARM LED (P3LA) TX ALARM LED (P4LA) COMMON ALARM LED (P4LA) CABINET ALARM (K1) TX ALARM Alarm code: H7 (PLUG-OUT) PCB P4LD/E missing or not properly inserted. RX ALARM LED (P4LA) COMMON ALARM LED (P4LA) CABINET ALARM (K1) RX ALARM BURST/SNR (K4); (jumper BU) Alarm code: H7 (PLUG-OUT) Dummy load P3LK inserted instead WARNING LED (P4LA): (yellow) of RF hybrid P3LA Alarm code L5 (Local loop test) PCB P4LD/E missing or not properly inserted. RX ALARM LED (P4LA) COMMON ALARM LED (P4LA) CABINET ALARM (K1) RX ALARM BURST/SNR (K4); (jumper BU) Alarm code: H7 (PLUG-OUT) Unit switched to the remote loop test mode WARNING LED (P4LA): (yellow) REMOTE LOOP ON LED (P4LB) BURST/SNR or WARNING (jumper BU/WA) A jumper at the rear of the back plane PCB (P7LB) Yellow WARNING LED lights after T = 4sec is not in its normal position and CABINET ALARM (K1) is activated Alarm code : P pilot switch “OFF” A AGC switch “BLOCK” PA both set

SNR too low COMMON ALARM LED (P4LA) SNR < 9 dB respectively 15 dB SNR LED CABINET ALARM (K1) RX ALARM (K3) BURST/SNR (K4) (jumper BU) Alarm code: E


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Fault/operating status Alarm displayed/signalled Signal strength at receiver too low COMMON ALARM LED (P4LA) RX level 2 to 5 dB below band of regulation RX LED CABINET ALARM (K1) RX ALARM (K3)* BURST/SNR (K4)* (umper BU) Alarm code: E Transmitter power too low COMMON ALARM LED (P4LA) (below the level according to Table 2.5) TX ALARM LED (P3LA) TX ALARM LED (P4LA) CABINET ALARM (K1) TX ALARM (K2)* Alarm code: E Alarm by NSD 50 COMMON ALARM LED (P4LA) Fault on the interface or NSD 50 processor PCB CABINET ALARM (K1) RX ALARM (K3)* TX ALARM (K2)* Alarm code: H0 NSD 50: LED AL Interface: LED AL1/LED AL2 Failure of the digital transit filter E1LA (in O4LA) COMMON ALARM LED (P4LA) CABINET ALARM (K1) RX ALARM (K3)* TX ALARM (K2)* Alarm code: H0 (AF COMMON ALARM) Digital transit filter E1LA (on O4LA) generating WARNING LED low priority alarm (check sum error) ALARM CODE H1 (warning) NSK 5 MODEM WARNING LED Check sum/aux. supply/carrier alarm Alarm code: H1 (warning) (carrier alarm: jumper DC is set) Signal processor in P4LA LED warning (check sum error) CABINET ALARM (K1) BURST/SNR WARNING (4) (jumper WA) Alarm code: H3 (Warning P4LA DSPW) * Relay contacts optional.

Table 2.9 Typical cases of alarm


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2.2.7 Main RF components

Frequency range and channel allocation

The transmitter and receiver channels can occupy any of the 4 kHz slots in the frequency band from 24 to 500 kHz. The gross bandwidth of a transmitter or receiver channel is 4 kHz.

Programming channels

The frequency of a channel can be changed without difficulty on site.

The units which determine frequency are the synthesizer P4LG, the RF transmitter filter E5LA/B and the re-ceiver filter on the RF receiver converter P4LD/E. They can be set at intervals of 4 kHz.

There are two alternative transmitter RF filters in use:

E5LB 24-100 kHz bandwidth 8 kHz one and two-channel operation bandwidth 16 kHz three and four-channel operation E5LA 100-500 kHz bandwidth 8 kHz one and two-channel operation bandwidth 16 kHz three and four-channel operation

There are also two alternative RF receiver converters:

P4LD bandpass width 4 kHz one (three) channel operation P4LE bandpass width 8 kHz two and four-channel operation

Channel allocation, parallel operation

Related transmitter and receiver channels may be adjacent. Where several equipments are connected in parallel, the frequency spacing specified in Section 4.1 must be observed. Providing this is maintained, the maximum additional attenuation is 1.5 dB.

Setting the transmitter power

The transmission level is set in relation to the channel allocation scheme in use to the maximum peak power available of 40 W. The setting is determined by simply summing the voltage weightings of the various channels at the RF transmitter converter P4LF and setting the value obtained on the DIL switches. Provision is made for operation at a reduced transmitter power.

Power amplifier overload protection

The gain of the power amplifier P1LA is controlled to protect it against an overload due to a mismatch between RF output and transmission line.


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Purpose of the RF hybrid

The purpose of the RF hybrid P3LA/B* is to decouple the receiver from its own transmitter. Excellent transverse attenuation of the hybrid is achieved by tuning its RLC network to the actual line impedance. In the event of a TX ALARM (O/P stage alarm, auxiliary supply failure), an auxiliary relay* in the hybrid isolates the power amplifier from the transmitter filter. This avoids any mutual influence between equipments in parallel.

Matching and protection devices

The standard unbalanced O/P impedances at the RF interface are 75 Ohm or 125 Ohm. Gas discharge arrestors can be fitted to the RF output to protect them against transient overvoltages. Their general use is prescribed at system voltages of 220kV and above. An optional matching unit Type P1BG/A1AE* is available for balanced 150 Ohm cables, which is fitted to the rear wall of the cubicle.

2.2.8 Two-channel operation

By adding a rack assembly Type P7LB fitted with the corresponding units, the ETL can be expanded for two-channel operation. The AF functions, the conversion to the first intermediate frequency and the supervision facilities of channel 2 are identical to those of channel 1.

Compared with one-channel operation, the racks of a two-channel scheme differ in the following points:

Channel 1:

- The Channel 1 RX RF converter Type P4LD is replaced by the Channel 2 RX RF converter Type P4LE. - The other units are the same as for one-channel operation.

Channel 2:

- The TX RF converter Type P4LF and the RX RF converter Type P4LD are replaced by the channel link Type V9LK.

- The frequency synthesizer Type P4LG is replaced by the synthesizer Type P4LI. - The intermediate frequency converter Type P4LC uses carriers of 636 kHz and 156 kHz provided by

P4LI, which are shifted by 4 kHz in relation to channel 1. - The other units are the same as for one-channel operation.

2.2.9 Three and four-channel operation

By adding further Type P7LB racks fitted with the corresponding units, the ETL can be expanded for three or four-channel operation.

The AF functions, the conversion to the first intermediate frequency and the supervision facilities are identi-cal in all the channels.

(* Optional)


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The configuration and functions of the rack assembly for Channel 3 correspond to those of Channel 1.

The configuration and functions of the rack assembly for Channel 4 correspond to those of Channel 2.

Compared with one-channel operation, the racks of a three or a four-channel scheme differ in the following points:

Channel 3:

- The Channel 3 units for three-channel operation are identical to those of Channel 1. For four-channel op-eration, the Channel 1 RX RF converter Type P4LD is replaced by the Channel 2 RX RF converter Type P4LE.

- The other units are the same as for one-channel operation.

Channel 4:

- The TX RF converter Type P4LF and the RX RF converter Type P4LD are replaced by the channel link Type V9LK.

- The frequency synthesizer Type P4LG is replaced by the synthesizer Type P4LI. - The intermediate frequency converter Type P4LC uses carriers of 636 kHz and 156 kHz provided by

P4LI, which are shifted by 4 kHz in relation to channel 3. - The other units are the same as for one-channel operation.


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2.2.10 Auxiliary supply

All ETL auxiliary supply systems provide the PLC equipment with an auxiliary supply, which is DC isolated from the station supply. Each channel rack has its own DC/DC converter. The power amplifier is DC isolated from all other circuits by transformers in I/P and O/P having a high insulation level.

The overall auxiliary supply system comprises two units:

- PSU which supplies the complete equipment - DC/DC converter (DC isolated supply for each channel rack)

Table 2.10 lists the PSU's and DC/DC converters used.

Supply for complete equipment ETL 41/42/43/44 AC supply 110 V AC Connected to power system by B5LC 230 V AC Station battery 48 V DC Connected to station battery by B5LA Supply for ETL 41/42/43/44 channel rack Type P7LB Single supply DC/DC converter Type B4LA 1 unit per P7LB rack *)

Redundant supply DC/DC converter Type B4LB 1 unit per P7LB rack

Table 2.10 Allocation of PSU's and DC/DC converters

*) ETL42: The smallest version of Channel 2 with the AF options 1 x O4LA (including E1LA) and O4LB/C (less NSD 50) can be supplied by the Channel 1 DC/DC converter B4LA.

*) ETL44: The smallest version of Channel 4 with the AF options 1 x O4LA (including E1LA) and O4LB/C (less NSD 50) can be supplied by the Channel 3 DC/DC converter B4LA.


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2.2.11 Testing facilities

There are a number of aids provided for testing and commissioning Type ETL PLC equipment.

Internal test generator

The standard P4LA unit is equipped with a test oscillator having an O/P signal of either 800 Hz or 3000 Hz (C/O switch) at 0 dBm or -3.5 dBm, which is available at sockets on the frontplate. With the aid of this oscillator, the transmitter level can be set and the transmitter and receiver circuits tested. The latter also requires the dummy load P3LK.

Status display

The following alarm and operating statuses are signalled by LED's on the frontplate of P4LA:

COM common alarm red WARNING low priority alarm yellow TX transmitter alarm red RX receiver alarm red SNR SNR alarm red P4LA watchdog (processor error) red SUP auxiliary supply stand-by green

During normal operation the display on the front of P4LA shows the AGC status (remaining regulation lee-way, normally 26 dB). In the event of a fault, a fault code can be presented on this display by briefly pressing the test tone button, which provides more information on the nature of the fault (see Table 2.8 "Table of alarm codes" in Section 2.2.6.2).

Audio test

A simple go/no-go test, which can be heard in the receiver of the service telephone, can be performed by injecting any of the AF signals at the test sockets on the front of the telephony interface O4LB/C.

Dummy load for local loop test facility

The transmitter is terminated by its rated load by inserting the dummy load P3LK in place of the RF hybrid. This then forms a local loop, which enables both transmitter and receiver to be fully tested. A frequency converter and corresponding control circuit in the device automatically switch the transmitter frequency to the receiver frequency when the dummy load is inserted.

Remote loop test facility

This is one of the most useful aids during commissioning and fault-finding on site, which enables the AF characteristic of a PLC receiver channel to be tested and its distortion to be equalized from one end of the transmission line.

In the remote loop test mode, the AF signal injected at the local end is detected by a PLL (phase-locked loop) circuit (tracking filter) in the terminal equipment at the remote end and looped at the correct signal


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strength to the remote transmitter to be returned to the local station. The REMOTE LOOP TEST is initialised, held and controlled by a microprocessor on P4LA. The procedure for performing the REMOTE LOOP TEST is described in Section 5.5.2.

Should a change of frequency become necessary as the PLC network expands, two optional tuning adapters are available for tuning the transmitter filter E5LA/B and the receiver filter on P4LD/E.

Utility Communication Systems Mechanical design ETL41/42/43/44

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3. MECHANICAL DESIGN

3.1 Construction

PLC equipment of the ETL series is constructed according to the K80 standard. All the units plug into 19" electronic equipment racks. The units inserted into the channel rack Type P7LB are 6U (266 mm) high and 220 mm deep; the units in the power amplifier rack Type P7LA are 3U (133 mm) high and 220 mm, respec-tively 160 mm deep. The units are secured by screws in the racks. The connectors of the units can be op-tionally coded.

The dimensions of the various alternative versions are given in Appendix A.1. In the standard version, the equipment racks are mounted in the hinged frame of a cubicle Type E35C (see Appendix A.1).

3.2 Units fitted

The locations of the units in the racks of equipment types ETL41/42/43/44 are to be found in Appendix A.1, which also includes a parts list with all the units.

3.3 Internal wiring

The signals are conveyed between the units in a channel rack P7LB via the back plane PCB (see Appendix A.3). The wiring between the channel rack P7LB and the power amplifier P7LA and also between channel racks in a multiple channel scheme is by means of 16 core ribbon cables Types V9LH/V9LI.

3.4 External connections

AF and alarm signals

The external AF and alarm signals within the PLC equipment are conducted by V9LA cables to the terminal strips in the cubicle. The allocation of AF and alarm signals to terminals can be seen from the block diagrams in Appendix A.2 (see also Appendix A.4).

Auxiliary supply connections

Inside the cubicle, the auxiliary supply is wired to the correspondingly marked Faston connectors mounted on the cover plate at the left-hand end of the power amplifier rack P7LA. The channel rack P7LB is supplied from a Faston connector via a connecting cable V9LL.

RF connection

75 Ohm cables with BNC connectors convey the RF signals between the ETL units and the two-way RF connector installed in the cubicle. The cables from the various units can be linked as required to the coaxial cables terminated at the connector.

Utility Communication Systems Technical data ETL41/42/43/44

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4. TECHNICAL DATA

All ETL equipment fully complies with, or is better than the requirements of the draft revision of IEC Publica-tion 495 covering single sideband power line carrier terminal equipment (August 1990).

4.1 System data

Operating mode: Single sideband with suppressed carrier, multiple conversion and first intermediate frequency 16 kHz.

Carrier frequency range: overall range 24 to 500 kHz programmable 40 to 500 kHz

Sideband normally transmitted: ETL 41/42/43/44

erect mode

ETL41 ETL42 ETL43 ETL44 Nominal bandwidth: 4 kHz 8 kHz 12 kHz 16 kHz Maximum line attenuation: 60 dB 54 dB 50 dB 48 dB

To allow for line noise level, the effective 35 to 30 to 25 to 23 to line attenuation should not exceed 40 dB 35 dB 30 dB 28 dB

Frequency spacing:

Frequency gap between channels of several equipments operating in parallel on a common line. - transmitter to its own receiver 0 kHz 0 kHz 0 kHz 0 kHz - transmitter to adjacent transmitter ≥8 kHz ≥8 kHz ≥12 kHz ≥16 kHz - transmitter to adjacent receiver ≥4 kHz ≥4 kHz ≥4 kHz ≥4 kHz - receiver to adjacent receiver 0 kHz 0 kHz 0 kHz 0 kHz Tapping loss introduced when several sets of PLC are connected to the same coupling equipment. - 2 transmitters with minimum gap of 8 kHz ≤1.5 dB ≤1.5 dB 12 kHz ≤1.5 dB 16 kHz ≤1.5 dB


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Nominal output impedance 75 or 125 ohm unbalanced Optional 150 ohm balanced Return loss in the transmitter band ≥12 dB Carrier frequency stability ±10 x 10-6 (≤ ±5 Hz) Useful AF bandwidth 300 to 3840 Hz (4 kHz overall bandwidth)

Attenuation distortion of the AF channel

Broadband repeater operation 0.3 to 3.84 kHz 0.3 to 0.4 kHz -0.9/+1.7 dB 0.4 to 3.7 kHz -0.9/+0.9 dB 3.7 to 3.84 kHz -0.9/+1.7 dB Broadband repeater operation 0.3 to 3.6 kHz (with 3.6 kHz low-pass filter) 0.3 to 0.4 kHz -0.9/+1.7 dB 0.4 to 3.4 kHz -0.9/+0.9 dB 3.4 to 3.6 kHz -0.9/+1.7 dB Speech band 0.3 to 3.4 kHz Refer to Fig. 8, IEC 495 without compandor Speech band 0.3 to 2.4 kHz Refer to Fig. 10, IEC 495 without compandor Speech band 0.3 to 2.2 kHz without compandor 0.3 to 0.4 kHz -0.9/+3.0 dB 0.4 to 0.6 kHz -0.9/+1.7 dB 0.6 to 1.4 kHz -0.9/+0.9 dB 1.4 to 1.8 kHz -0.9/+1.7 dB 1.8 to 2.2 kHz -0.9/+3.0 dB Speech band 0.3 to 2.0 kHz Refer to Fig. 10, IEC 495 without compandor Superaudio telecontrol band (PLC channel plus transit filter E1LA) Attenuation distortion in the programmed See Section 4.4.2 bandpass range


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Group delay distortion Broadband repeater operation 0.3 to 3.84 kHz 0.5 to 0.6 kHz ≤ 3 ms 0.6 to 1.0 kHz ≤ 1.5 ms 1.0 to 3.2 kHz ≤ 0.5 ms 3.2 to 3.7 kHz ≤ 3 ms Broadband repeater operation 0.3 to 3.6 kHz (with 3.6 kHz low-pass filter) 0.5 to 0.6 kHz ≤ 3 ms 0.6 to 1.0 kHz ≤ 1.5 ms 1.0 to 2.6 kHz ≤ 0.5 ms 2.6 to 3.4 kHz ≤ 1.5 ms 3.4 to 3.6 kHz ≤ 5 ms Speech band 0.3 to 3.4 kHz Refer to Fig. 9, IEC 495 Speech band 0.3 to 2.4 kHz Refer to Fig. 11, IEC 495 Speech band 0.3 to 2.2 kHz 0.4 to 0.5 kHz ≤ 5 ms 0.5 to 0.6 kHz ≤ 3 ms 0.6 to 1.0 kHz ≤ 1.5 ms 1.0 to 1.7 kHz ≤ 0.5 ms 1.7 to 1.9 kHz ≤ 3 ms Speech band 0.3 to 2.0 kHz Refer to Fig. 11, IEC 495 Superaudio telecontrol band (PLC channel plus transit filter E1LA with equalization of delay distortion according to Section 4.4.2) Delay distortion in the programmed See Section 4.4.2 bandpass range Linearity Without compandor and limiter ≤ ±0.3 dB referred to 0 dBm0 in a range of -10 ... 0 dBm0 Compandor characteristics Complies with CCITT G 162


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Harmonic distortion

350 Hz speech signal 4-wire: ≤ -40 dBm0 for each component at -3 dBm0 without compandor 2-wire: ≤ -30 dBm0 for each component at -3 dBm0 with compandor

Telecontrol signals ≤1 % at max. gain Near and far-end cross-talk: Interference level in speech band ≤ -50 dBm0p produced by any tone in superaudio band *) Near and far-end cross-talk attenuation ≥50 dB in multi-channel operation (ETL42/43/44) *) Quiescent noise *) ≤ -55 dBm0p AF off-set 0 Hz Supervision, alarms: Alarm is given under the following conditions: - loss of transmitter signal - loss of receiver signal (2 - 5 dB below the AGC range) - low SNR in speech and telecontrol channels (9, 15 dB) - loss of auxiliary supply - excessive impulse interference *) Note: The above tests are carried out with an artificial line having an attenuation of: 31 dB for the ETL41 25 dB for the ETL42 21 dB for the ETL43 19 dB for the ETL44


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Frontplate LED signals: Auxiliary supply on: SUP Transmitter alarm Tx Rx sig. strength alarm Rx Rx SNR alarm SNR Common alarm COM Low priority alarms yellow DSP/µP failure P4LA Alarm O/P contacts: - Cabinet alarm: 1 potentially-free N/C contact

(closes to give alarm) hermetically sealed dry reed relay, max. ratings: 15 W/60 V/500 mA AF muting - Slow muting Rx signal strength alarm: 2-5 dB below the AGC range SNR alarm: 9 dB, 15 dB Pick-up and reset delays: 2, 5, 10, 15 s

Selectable for the following AF O/P's:

O4LA: all telecontrol O/P's O4LB/C: speech O/P's. The PAX blocking criterion is also emitted. P4LB: AF O/P - Fast muting for burst noise Pick-up delay ≤ 10 ms at a (selectable for telecontrol O/P 3 of O4LA) burst noise level > 0 dBm0 /SNR < 0 dB) Reset delay 5 s


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Ambient conditions

Normal operation

Climatic conditions: Within specification: Temperature range -5 to +45 °C Relative humidity ≤ 95% Complies with IEC 721-3-3, Class 3K5 (see climatogramme 3K5 on Page 4 - 7) Operational: +55 °C Note: The equipment may not be operated at the higher temperature of +55°C for more than 24 hours. In

normal operation, humidity and temperature gradient must be such that condensation or the forma-tion of ice cannot occur.

Mechanical conditions: Complies with IEC 721-3-3, Class 3M1 Storage (equipment in packing) Climatic conditions: Temperature range -40 to +70 °C Complies with IEC 721-3-1, Class 1K5 Mechanical conditions: Complies with IEC 721-3-1, Class 1M1 Transport Climatic conditions: Temperature range -40 to +70 °C Complies with IEC 721-3-2, Class 2K4 Mechanical conditions: Complies with IEC 721-3-2, Class 2M1


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4.2 Transmitter Data

RF O/P power

Peak envelope power (PEP) including 40 W (+46 dBm) pilot signal under nominal load conditions at coaxial O/P ETL41 ETL42 ETL43 ETL44 Spurious signal suppression at the limits of the bandwidth ≥ 60 dB ≥ 60 dB ≥ 60 dB ≥ 60 dB 4 kHz from the band limits ≥ 70 dB 8 kHz from the band limits ≥ 70 dB 12 kHz from the band limits ≥ 70 dB 16 kHz from the band limits ≥ 70 dB 8 kHz from the band limits ≥ 80 dB 16 kHz from the band limits ≥ 80 dB 24 kHz from the band limits ≥ 80 dB 32 kHz from the band limits ≥ 80 dB Harmonic suppression ≥ 80 dB ≥ 80 dB ≥ 80 dB ≥ 80 dB Suppression of unwanted sidebands ≥ 80 dB ≥ 80 dB ≥ 80 dB ≥ 80 dB Pilot channel: Nominal frequency 3780 Hz ±30 Hz Options 2160 Hz ±30 Hz 2640 Hz ±30 Hz 3360 Hz ±30 Hz 3600 Hz ±30 Hz


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4.3 Receiver Data

RF sensitivity referred to the -24 dBm test tone level at the RF I/P:

Selectivity: · 0.3 Hz from the band limits: 70 dB · 4 kHz from the band limits: 100 dB Image rejection ≥ 80 dB IF rejection ≥ 80 dB Automatic gain control (AGC): AF O/P level remains within ±0.5 dB for a +14/-26 variation of RF I/P level. AGC time constant 0.5 dB/sec for level increase and decrease

Frequency response equalization range ±6 dB


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4.4 AF Interfaces

4.4.1 Telephony interfaces 2/4-wire PAX interface Type O4LC Transmitter path: 2-wire Nominal input level 0 dBr, 600 Ohms balanced Input level range -16 dBr to +6 dBr in steps of 0.25 dB 4-wire Nominal input level -3.5 dBr, 600 Ohms balanced Input level range -20 dBr to +10 dBr in steps of 0.25 dB Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB DC resistance ≥ 2 MΩ Speech cut-off frequency 1.8 kHz - 3.4 kHz in steps of 200 Hz adjustable: standard cut-off frequencies: 2000 Hz 2200 Hz 2400 Hz 3400 Hz Limiter characteristic: I/P level ≤ -1 dBm0: linear O/P level -1 ... 0 dBm0: limiter becomes active +15 dBm0: O/P level +3 dBm0 Telephony signalling: M wire *) Pilot oscillator keyed by external contact. max. rate: 50 Baud Loop current 2-10 mA permissible voltage drop ≤2 V


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Hybrid switching *) Hybrid connected when external contact closed

Loop current 2-10 mA Permissible voltage drop ≤2 V Speech control *) Compandor switched off when (transit/local) external cable closed Loop current 2-10 mA Permissible voltage drop ≤2 V Hybrid transverse loss ≥40 dB under specified matched conditions

Receiver path:

Nominal 2-wire O/P level -7 dBr, 600 ohms balanced O/P level range -16 dBr to +6 dBr in steps of 0.25 dB Nominal 4-wire O/P level -3.5 dBr, 600 ohms balanced O/P level range -20 dBr to +10 dBr in steps of 0.25 dB Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB DC resistance ≥ 2 MΩ Speech cut-off frequency 1.8 kHz - 3.4 kHz in steps of 200 Hz adjustable: standard cut-off frequencies: 2000 Hz 2200 Hz 2400 Hz 3400 Hz Telephone signalling: E-wire Solid-state N/O or N/C contact Max. ratings: 50 mA/60 V Pulse distortion ≤ ±1.5 ms PAX blocking (Optional) N/O contact Contact closes for a receiver alarm Hermetically sealed dry reed relay Max. ratings: 100 mA/60 V *) DC isolation can be provided for the signal I/P's by fitting an optionally available DC/DC converter. Insulation level 500 V, 50 Hz, 1 min.


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Service telephone

Standard 4-wire hand-set with 1000 Hz call tone Operating modes - point-to-point with 1000 Hz call tone

4-wire PAX interface O4LB

Transmitter path:

Nominal 4-wire I/P level -3.5 dBr, 600 ohms balanced I/P level range -20 dBr to +10 dBr in steps of 0.25 dB Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB DC resistance ≥ 2 MΩ Speech cut-off frequency 1.8 kHz - 3.4 kHz in steps of 200 Hz adjustable: standard cut-off frequencies: 2000 Hz 2200 Hz 2400 Hz 3400 Hz Limiter characteristic: I/P level ≤ -1 dBm0: linear O/P level -1 ... 0 dBm0: limiter becomes active +15 dBm0: O/P level +3 dBm0 Telephony signalling: M wire *) Pilot oscillator keyed by external contact. max. rate: 50 Baud Loop current 2-10 mA permissible voltage drop ≤2 V Speech control *) Compandor switched off when (transit/local) external contact closed Loop current 2-10 mA Permissible voltage drop ≤2 V


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Receiver path:

Nominal 4-wire O/P level -3.5 dBr, 600 ohms balanced O/P level range -20 dBr to +10 dBr in steps of 0.25 dB Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB DC resistance ≥ 2 MΩ Speech cut-off frequency 1.8 kHz - 3.4 kHz in steps of 200 Hz adjustable: standard cut-off frequencies: 2000 Hz 2200 Hz 2400 Hz 3400 Hz Telephone signalling: E-wire Solid-state contact Max. ratings: 50 mA/60 V Pulse distortion ≤ ±1.5 ms PAX blocking (Optional) N/O contact Contact closes for a receiver alarm Hermetically sealed dry reed relay Max. ratings: 100 mA/ 60 V *) DC isolation can be provided for the signal I/P's by fitting an optionally available DC/DC converter. Insulation level 500 V, 50 Hz, 1 min.

Service telephone

Standard 4-wire hand-set with 1000 Hz call tone Operating modes - point-to-point with 1000 Hz call tone


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4.4.2 Telecontrol interfaces

Telecontrol interface O4LA

Telecontrol I/P's

3 I/P's Decoupled, independently adjustable 600 ohms balanced Nominal I/P level 0 dBr I/P level range -20 to +10 dBr in steps of 0.25 dB Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB Minimum level for maximum -20 dBm RF output power

Telecontrol O/P's

3 O/P's Decoupled, independently adjustable

600 ohms balanced Programmable as transit filter or broadband O/P's. - Nominal O/P level 0 dBr, 600 ohms balanced - O/P level range (single tone) -20 dBr to +10 dBr in steps of 0.25 dB across 600 ohms - Max. O/P level (PEP) +14 dBm across 600 ohms Balance referred to ground ≥ 56 dB Return loss ≥ 20 dB Note: The number of telecontrol I/P's and O/P's can be doubled by inserting an additional telecontrol PCB

Type O4LA.


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Optional transit filter Transit filter can be inserted either in the Tx (Sub-unit Type E1LA) path (telecontrol I/P 2) or in the Rx path (any of the 3 O/P's). Standard filters (unequalized group delay distortion) Bandstop attenuation ≤ 50 dB Bandpass attenuation flat in a band of ±0.9 dB Cut-off frequencies 360 Hz to 3720 Hz adjustable in steps of 60 Hz Selectivity ≥ 50 dB/120 Hz 10 filters with group delay distortion of ETL channel and filter equalized. Bandpass 2160 Hz - 3600 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2000 Hz and ≥ 3720 Hz Group delay see fig. 4.1 Bandpass 2160 Hz - 3480 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2000 Hz and ≥ 3580 Hz Group delay see fig. 4.2 Bandpass 2400 Hz - 3600 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2200 Hz and ≥ 3720 Hz Group delay see fig. 4.3 Bandpass 2400 Hz - 3480 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2000 Hz and ≥ 3580 Hz Group delay see fig. 4.4 Bandpass 2520 Hz - 3600 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2400 Hz and ≥ 3720 Hz Group delay see fig. 4.5 Bandpass 2520 Hz - 3480 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f µ 2400 Hz and ≥ 3580 Hz Group delay see fig. 4.6 Low-pass 3600 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f ≥ 3720 Hz Group delay see fig. 4.7


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Low-pass 3480 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f ≥ 3580 Hz Group delay see fig. 4.8 High-pass 2520 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f ≥ 2340 Hz Group delay see fig. 4.9 High-pass 2760 Hz Ripple +0.9 dB / -0.9 dB Rejection ≥ 50 dB for f ≥ 2700 Hz Group delay see fig. 4.0

Fig. 4.1 Group delay distortion, Bandpass 2160 - 3600 Hz



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Fig. 4.7 Group delay distortion, Lowpass 3600 Hz

Fig. 4.8 Group delay distortion, Lowpass 3480 Hz


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Fig. 4.9 Group delay distortion, Highpass 2520 Hz

Fig. 4.10 Group delay distortion, Highpass 2760 Hz


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AF converter Type P4LB

1 boostable power AF I/P for external 600 ohms teleprotection signalling equipment and for AF repeater applications Nominal I/P level -10 Br I/P level range -20 dBr to 0 dBr Return loss ≥ 20 dB Balance referred to ground ≥ 56 dB Programmable boosting ratios 0 db, 5 dB, 7 dB, 9 dB Boosting input DC isolated I/P with external +5 V supply Boosting criterion ON Ext. contact closed OFF Ext. contact open 1 AF O/P for external teleprotection 600 ohms signalling equipment and for AF repeater applications Standard O/P level setting -10 dBr Alternative O/P level setting -3.5 dBr Return loss ≥ 20 dB Balance referred to ground ≥ 56 dB Optional low-pass filter 3600 Hz for standard pilot suppression


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4.5 Testing facilities

Internal test oscillator in P4LA 0 dBm ±0.5 dB, 800 Hz/3000 Hz -3.5 dBm ±0.5 dB Other settings possible by choice of resistor Audio test (standard) in O4LB/C - Bandwidth 100 Hz to 10000 Hz - I/P level range -40 dBu to +10 dBu - I/P impedance High-impedance Dummy load (option) in P3LK - Nominal load resistance 20 ohms - Tx power rating PEP 80 W

Continuous 40 W - Tx/Rx local loop test Facilitates complete testing of the local ETL Tx/Rx equipment including the RF receive filter. AGC test facility for an RF level change of +10 dB/-20 dB.


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4.6 Auxiliary supplies

ETL41 ETL42 ETL43 ETL44 AC supply 110/230 V 110/230 V 110/230 V AC 110/230 V +10/-15 % +10/-15 % +10/-15 % +10/-15 % 45 to 65 Hz 45 to 65 Hz 45 to 65 Hz 45 to 65 Hz Power consumption - Stand-by (only pilot) 95 VA 110 VA 145 VA 175 VA - Normal operation *) 130 VA 140 VA 165 VA 195 VA - Single tone per channel 285 VA 225 VA 265 VA 290 VA Battery supply 48 VDC 48 VDC 48 VDC 48 VDC +20 % +20 % +20 % +20 % -15 % -15 % -15 % -15 % Ripple ≤ 5 % pp ≤ 5 % pp ≤ 5 % pp ≤ 5 % pp Power consumption - Stand-by (only pilot) 80 W 90 W 100 W 120 W - Normal operation *) 100 W 110 W 115 W 135 W - Single tone per channel 210 W 170 W 185 W 205 W Reflected noise ≤ 3 mV psophometrically weighted The noise suppression characteristic complies with VDE 871, Class B. *) Typical use of channel: speech + 600 Bd + pilot.


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4.7 Insulation tests and electromagnetic compatibility

Unbalanced carrier I/O

Impulse voltage test 5 kV, 1.2/50 µs IEC 255-4, Class 3 between terminals and ground HF interference test 2.5 kV IEC 255-22-1, Class 3 Fast electrical transients/bursts 2 kV IEC 801-4, Class 3

Balanced carrier I/O

Voltage withstand 2000 V r.m.s., 50 Hz, 1 min. IEC 255-5 Insulation resistance ≥ 100 MΩ, 500 V DC IEC 255-5 CM DM Impulse voltage test 5 kV 5 kV IEC 255-4, Class 3 HF interference test 2.5 kV 1 kV IEC 255-22-1, Class 3 Fast electrical transients/bursts 2 kV IEC 801-4, Class 3


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AF I/O's Voltage withstand 500 V r.m.s., 50 Hz, 1 min. IEC 255-5 Insulation resistance ≥ 100 MΩ, 500 V DC IEC 255-5 CM DM Impulse voltage test 1 kV 1 kV IEC 255-4, Class 2 HF interference test 1 kV 0.5 kV IEC 255-22-1, Class 2 Fast electrical transients/bursts 1 kV IEC 801-4, Class 3 Alarm and signalling contacts Voltage withstand *) 500 V r.m.s., 50 Hz, 1 min. IEC 255-5 Insulation resistance *) ≥ 100 MΩ, 500 V DC IEC 255-5 CM DM Impulse voltage test 1 kV 1 kV IEC 255-4, Class 2 HF interference test 1 kV 0.5 kV IEC 255-22-1, Class 2 Fast electrical transients/bursts 1 kV IEC 801-4, Class 3 *) DC isolate signalling I/P (option)


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AC auxiliary supply I/P Voltage withstand 2000 V r.m.s., 50 Hz, 1 min. IEC 255-5 between terminals and ground Insulation resistance ≥ 100 MΩ, 500 V IEC 255-5 CM DM Impulse voltage test 5 kV 5 kV IEC 255-4, Class 3 HF interference test 2.5 kV 1 kV IEC 255-22-1, Class 3 Fast electrical transients/bursts 2 kV IEC 801-4, Class 3 Station battery auxiliary supply I/P Voltage withstand 2000 V DC ´2, 1 min. IEC 255-5 between terminals and ground Insulation resistance ≥ 100 MΩ, 500 V DC IEC 255-5 CM DM Impulse voltage test 5 kV 5 kV IEC 255-4, Class 3 HF interference test 2.5 kV 1 kV IEC 255-22-1, Class 3 Fast electrical transients/bursts 2 kV IEC 801-4, Class 3 Frontplate test sockets Electrostatic discharge 8 kV IEC 801-2 Induced electromagnetic fields IEC 801-3 10 V/m for equipment in closed cubicles


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4.8 Physical dimensions and weights

ETL41 dimensions and weights

Equipment racks: P7LA 19" conforming to ASA Standard P7LB Height Width Depth Dimensions: 399 mm 482 mm approx. 350 mm Weight: 22 kg fully equipped


Equipment racks: P7LA 19" conforming to ASA Standard 2 x P7LB Height Width Depth Dimensions: 666.8 mm 482 mm approx. 350 mm Weight: 35.5 kg fully equipped


Equipment racks: P7LA 19" conforming to ASA Standard 3 x P7LB Height Width Depth Dimensions: 933.5 mm 482 mm approx. 350 mm Weight: 47 kg fully equipped


Equipment racks: P7LA 19" conforming to ASA Standard 4 x P7LB Height Width Depth Dimensions 1200.2 mm 482 mm approx. 350 mm Weight: 58.5 kg fully equipped

Utility Communication Systems Principle of operation ETL41/42/43/44

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5. PRINCIPLE OF OPERATION

5.1 Modulation scheme

ETL41/42/43/44 PLC equipment employs single sideband modulation.

The transmitter has three stages of modulation with suppressed carrier. Demodulation in the receiver is performed in four stages. This scheme reduces considerably the complexity of the RF filters in transmitter and receiver and thus simplifies the tuning of the RF channels, whilst maintaining high receiver selectivity.

Figure 5.1 shows the modulation scheme used for one and two-channel operation. The first stage of modu-lation converts the 0-4 kHz AF bands of channels 1 and 2 to an intermediate frequency in the range IF1 = 16-20 kHz. The unwanted sidebands are suppressed by the IF filter, to which the signals then go. Together with the carrier (local oscillator) frequency of 640 kHz, channel 1 is converted to the second inter-mediate frequency in the range IF2 = 620-624 kHz. Channel 2 is similarly converted in the case of the two-channel version to the intermediate frequency IF2 = 616-620 kHz with the aid of a carrier frequency of 636 kHz. Both channels are then stepped up to the RF transmission carrier range by a further stage of modulation and the RF carrier TXFC.

Demodulation by the receiver takes place in a similar manner.

Using the RF oscillator RXFC, the first demodulator stage steps the carrier frequency down to the intermediate frequency ranges IF3 = 620-624 kHz, respectively 616-620 kHz. The next demodulator converts the channel 1 and 2 signals to the intermediate frequency range IF2 = 140-144 kHz, respectively 136-140 kHz with the aid of the internal carrier frequency 480 kHz. The two signals are then reduced to the IF1 range of 16-20 kHz using the internal carrier frequencies 160, respectively 156 kHz. The original AF bands of 0-4 kHz are achieved by a final stage of conversion with the carrier frequency 16 kHz.

The transmission capacity can be doubled to 4 channels by applying the same modulation principle for channels 3 and 4. The intermediate frequencies of channels 3 and 4 are achieved by oscillator frequencies TXFC in the transmitter and RXFC in the receiver, which are shifted by 8 kHz. The erect mode of all the channels is transmitted. The modulation scheme for three and four-channel operation is shown in Fig. 5.2.


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Fig. 5.1 Modulation scheme for ETL41/42


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Fig. 5.2 Modulation scheme for ETL43/44


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5.2 Carrier frequency section

See block diagram 5HYN589136-CA for the carrier frequency section of Channel 1 in Appendix A.2.

5.2.1 Transmitter

Transmitter part of AF converter P4LB

The various AF signals, which are transferred to the AF transmitter bus by the speech and telecontrol interfaces, the teleprotection unit NSD 50 and the VFT channel of NSK 5, are multiplexed on this unit and converted into the intermediate frequency IF1 = 16-20 kHz by the first modulator stage.

The telecontrol and speech signals pass from their respective AF buses via I/P's A12, C12 and C13 to the I/P and multiplexing amplifiers and thence to the AF IF modulator.

Teleprotection signals from the incorporated NSD 50 are fed in via the I/P C11, which cannot be interrupted.

The auxiliary AF I/P's A6 and C6 are DC isolated and can be used for connecting an external teleprotection signalling equipment or for the broadband relaying of AF transit signals.

The two auxiliary signals TX PILOT and TEST TONE generated on the P4LA unit are connected to the separate I/P's A4 and A6.

After undesirable modulation products have been suppressed by a 20 kHz low-pass filter, the multiplexed and modulated first IF TXIF1 passes via O/P C2 to the IF converter P4LC.

The 16 kHz carrier (local oscillator) needed for modulating from AF to IF1 and demodulating from IF1 to AF is derived from the 7.68 MHz quartz oscillator, the signal of which is connected to pins A30 and C30.

The tripping and power boosting criteria are derived by the BOOST LOGIC from control signals, which come from the teleprotection unit NSD 50 and any external transfertripping unit connected. These determine the brief interruption of the speech and pilot signals and of appropriately programmed telecontrol channels. The power of the tripping signal is boosted to the maximum power capability of the transmitter.

The control signals TX SPEECH OFF, PILOT SWITCH and BOOST generated by the NSD 50 are applied to the BOOST LOGIC at logic signal level via pins C9, A10 and C10 and result in the following:

TX SPEECH OFF: is generated when NSD 50 starts or emits a tripping signal and interrupts transmission of the:

- speech signal TX SPEECH - transit signal AUX. AF TX - TEST TONE when a REMOTE LOOP signal is applied

PILOT SWITCH: appears together with the NSD 50 tripping signal and interrupts

- the pilot signal TX PILOT at the transmitter


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BOOST: appears together with the NSD 50 tripping signal and interrupts transmission of:

- those TXAF-D channels which may be interrupted - the transit signal AUX. AF TX - the TEST TONE when a REMOTE LOOP signals is applied

sets power boosting for:

- the TX AF tripping signal from NSD 50 - an external teleprotection unit to 0 dB

The AUX. BOOST signal emitted by an external teleprotection signalling equipment and connected to I/P's A24 and C24 results in the following:

AUX. BOOST appears together with tripping signal of an external teleprotection unit and interrupts at the transmitter end:

- those TXAF-D channels, which it is permissible to interrupt - the speech signal TX SPEECH - the TEST TONE when a REMOTE LOOP signal is applied

sets power boosting for:

- an external teleprotection unit

The AUX. BOOST criterion can be made available externally either with DC isolation via an opto-coupler and external auxiliary supply or via an auxiliary relay contact and the internal -12 V supply (jumpers TA, TB and TC).

A further criterion, which influences the BOOST LOGIC, is the signal TXB from P4LA via I/P A7. This signal is generated when the remote loop mode has been successfully initialised and interrupts, apart from the NSD 50 teleprotection signal TXAF, all the AF signals at the transmitter end. It also blocks the AUX. AF OUTPUT at the receiver end.

AF signals can be injected for test purposes (checking the frequency/amplitude characteristic) at sockets (4) and (5) on the frontplate. The LED marked REMOTE LOOP lights on the frontplate, when the equipment is in the remote loop test mode. The remote loop test mode is discontinued should a teleprotection signal be generated.

Fail-safe test sockets are also provided on the frontplate for checking the transmitter signals AUX AFTX (auxiliary AF I/P) and TXAF (multiplexed AF signal).

Transmitter part of IF converter P4LC

The TXIF1 filter in this unit detects the upper sideband of the TXIF1 signal coming from AF converter P4LB, which lies between 16.3 kHz and 19.85 kHz and is applied to A2. The filter permits the upper sideband to pass, whilst the lower sideband and any remnants of the carrier from the preceding modulator stage are suppressed. The O/P signal from the filter continues to the next stage of modulation, where in the one-


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channel mode it is converted to the IF 620-624 kHz by mixing it with the 640 kHz carrier. In two-channel mode, the second channel is converted to the IF 616-620 kHz by mixing it with the 636 kHz carrier. A low-pass filter then follows, after which the signal appears at the balanced O/P of terminals C3 and C4 and passes to the RF modulator P4LF.

Fail-safe test sockets are provided on the frontplate for checking the signal TXIF1.

The frequency of 640 kHz needed for conversion is obtained by division from the 7.68 MHz quartz oscillator signal from the carrier synthesizer P4LG, which is applied to I/P's A30 and C30. The carrier TXIF2-FC = 636 kHz needed for two-channel operation is obtained by division of the doubled frequency of 1272 kHz provided by P4LI and connected to I/P's A9 and C9. This frequency is selected automatically for two-channel operation by the signal IF2 SELECT at I/P C6.

Transmitter RF converter P4LF

This unit converts the transmitter IF signal TXIF2 to the desired frequency of the RF channel. The signal coming from IF converter P4LC goes via the semi-balanced I/P A3/A4 to the summation amplifier and filter block TX-IF2. The O/P signal from the filter is the lower sideband from 616-620 kHz, which then passes via matching components and a isolating amplifier to the next stage of modulation. The filter has an overall bandpass range of 616-624 kHz and is used in both one and two-channel operation.

A low-pass filter filters the O/P signal from the RF modulator before it is applied to the RF pre-amplifier used for setting the transmitter level. The transmitter level is set according to the allocation of channels. Setting is a simple procedure involving the positioning of DIL switches. The setting is determined by adding the voltage weightings of the individual channels. A potentiometer is provided for trimming the transmitter power (balancing the attenuations of transmitter filter and hybrid, which are frequency dependent). The RF pre-amplifier O/P signal TXRF drives the O/P stage in the power amplifier unit P7LA. It reaches the O/P stage via the two-wire O/P C1/C2 and the connector X178.

Two fail-safe test sockets are provided on the frontplate for checking the signals TXIF2 and TXRF.

The carrier signal 2TXFC is applied to the I/P's A12 and C12. Following a stage of amplification and a divider circuit, it is applied as a push-pull signal to the transmitter modulator. The filtered and attenuated carrier signal TX CARRIER is fed via O/P A7 to the pilot and supervision unit P4LA for monitoring.

In normal operation, a portion of the RF O/P signal TX-RF is available at I/P A1, which can be used option-ally for selectively monitoring the transmitter in the unit P4LA. However, due to the filter circuit which follows, the signal has no influence on this unit in normal operation.

When the dummy load is inserted, i.e. in the LOCAL LOOP mode, the LOCAL LOOP criterion is determined by a superimposed DC. This criterion is evaluated on the P4LA and P4LB units and also causes the carrier 2TXFC to be switched to the modulator stage of the dummy load P3LK.


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5.2.2 Receiver

Receiver RF demodulator (converter) P4LD

The RF signal RX-RF received via the power line is conducted by a two-wire link from the input potentiome-ter of the hybrid to pins 15/16 of the connector X178 and thence to I/P A1/C1 and the filter RX-RF. The at-tenuator at the input of the filter firstly makes the input impedance independent of potentiometer setting for the tunable receiver filter which follows, and secondly compensates the filter's frequency dependent attenu-ation. The three-stage receiver bandpass filter provides a first stage of selectivity, but its main purpose is to suppress the transmitter signals of local parallel PLC equipment.

Following voltage adjustment and impedance conversion, the RF converter steps the frequency down to the intermediate frequency IF3 = 620-624 kHz.

The internal carrier RXFC needed by the RF converter for this purpose is derived by conditioning and divid-ing the frequency of a signal provided by P4LG and applied to the I/P C20/C21.

A portion of the carrier RX CARRIER is fed via a low-pass filter and O/P A17 to the pilot and supervision unit P4LA for monitoring.

In the local loop test mode with the dummy load inserted, the signal LOCAL LOOP generated by the trans-mitter RF converter P4LF and applied to I/P A5 switches the receiver RF carrier 2RXFC via O/P C17 and connector X178 to the modulator stage of the dummy load P3LK.

The subsequent filter has a bandwidth of 8 kHz and can thus also be used for two-channel operation. Its purpose is to suppress the image band IF and residual carrier. Another stage of level and impedance adjustment takes place before the next demodulator converts the signal to the second IF of IF2 = 140-144 kHz.

The carrier of 480 kHz needed in this case is obtained by directly dividing the frequency of the 7.68 MHz quartz oscillator, which is connected to I/P A30/C30.

The filter RX-IF2 comes next and makes a first contribution to the receiver's excellent selectivity. From this filter, the signal passes via a further amplifier and O/P A19/A20 to the IF converter P4LC. In two-channel operation (use of P4LE), channel 2 is available at O/P A12/A13.

Two fail-safe test sockets are provided on the frontplate for checking the signals RX-RF and RX-IF2.


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Receiver part of IF converter P4LC

The signal RX-IF2 has a two-wire connection to demodulator I/P C19/C20 and is converted to the interme-diate frequency IF1 with the aid of the 160 kHz carrier. The lower sideband of the double-sideband signal is then extracted by the sharp cut-off characteristic of filter RXIF1. This filter has a bandpass range of 16.3 kHz-19.85 kHz, which largely determines the receivers selectivity.

The signal then goes to an amplifier with AGC, which is able to maintain a constant O/P level in the pres-ence of a fluctuating RF signal. The now constant signal RXIF1 is amplified once more before passing via O/P A17 to the receiver part of P4LB. The gain of the O/P amplifier can be increased by 10 dB by selecting the RX LOW DISTORTION mode on the back plane PCB of the channel rack, which applies a corresponding signal to I/P A19.

A fail-safe test socket marked RXIF1 is provided on the frontplate for checking the AGC regulated O/P sig-nal.

The AGC voltage is obtained by comparing the received AF pilot with a reference level on P4LA and is con-nected to I/P A3 of P4LC. The I/P amplifier converts the AGC voltage to a proportional current, whilst at the same time linearising the characteristic of the field effect transistor, which is the device controlling the AGC feedback line. Compensation of the FET's temperature behaviour is also included.

The local oscillator frequency of 160 kHz required for the conversion to IF1 is achieved by division of the 7.68 MHz quartz oscillator signal coming from P4LG and connected to I/P A30/C30. The additional oscilla-tor frequency of 156 kHz needed for two-channel operation is derived by division of the double frequency of 312 kHz provided by P4LI and connected to I/P A15/C15. In the two-channel mode, this frequency is se-lected automatically by the switch-over signal IF2 SELECT connected to I/P C6.

Receiver part of AF converter P4LB

Before reaching the IF1 to AF demodulator, the receiver signal RXIF1 at I/P C17 is connected either directly or via an equalizing circuit to a limiter circuit and the 20 kHz low-pass filter, which attenuates harmonics generated by the IF level regulator. The distortion equalizer is only in circuit, if attenuation distortion on the PLC channel makes its use necessary. The distortion equalizer is programmed using jumpers RA/RB/RC/RD and the programming switches S2 and S3.

The distortion equalizer is switched off either by the jumper plugs on the frontplate or by the LOCAL LOOP signal.

The next demodulator converts the signal to its original AF. The low-pass filter, which follows it suppresses undesirable byproducts of the IF1 to AF demodulator. Following adjustment of signal level, a broadband AF signal of 3.85 kHz is available at O/P A20 and optionally a AF signal of 3.6 kHz at O/P A18, i.e. with sup-pressed standard pilot. The bus drivers in the respective O/P's are capable of driving the I/P's of several AF interfaces (AF options) connected to the receiver AF bus.

The AF signal at O/P C20 is part of the AGC loop. The pilot signal is derived from this signal on P4LA. The pilot signal is processed digitally and serves a number of purposes such as receiver level control, monitoring receiver gain and signal quality, synchronisation of receivers, dialling signal transfer and the transfer of teleprotection signals in conjunction with the teleprotection equipment NSD 50.


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On the standard equipment, the 3.85 kHz AF channel and optionally the 3.6 kHz AF channel with sup-pressed standard pilot are available at the DC isolated auxiliary O/P A8/C8 marked AUX. AF OUTPUT. This O/P facilitates the connection of an external teleprotection unit or relaying of transit (repeater) signals.

If the signal quality is too poor, the O/P can be blocked by the SLOW MUTE signal from the pilot and super-vision unit.

The signalling interfaces "E" and "M" at O/P's A26/C26 and A30/C30 are provided for repeating dialling im-pulses in the transit mode. The E-WIRE circuit is DC isolated by an opto-coupler. The corresponding signals can be checked at the test sockets "E" and "M" on the frontplate. Fail-safe sockets marked AUX. AF RX (auxiliary AF O/P) and RXAF are also provided for checking the receiver AF signals.


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5.3 Carrier synthesizer (local oscillator) P4LG

See block diagram 5HYN589136-CA for the converter section of Channel 1 in Appendix A.2.

The programmable transmitter and receiver carrier frequencies 2TXFC and 2RXFC are generated by this unit. The two carriers are derived by the synthesizers PLL TX and PLL RX from the 16 kHz reference fre-quency, which itself is derived from the 7.68 MHz quartz oscillator by a frequency divider. The two RF carri-ers are applied to the transmitter RF converter P4LF, respectively the receiver RF converter P4LD at twice the frequency as 2TXFC and 2RXFC.

The quartz oscillator can be connected as master or slave by appropriately closing jumpers MA and MB, re-spectively SA and SB. In the slave mode, the frequency of the quartz oscillator is controlled by the voltage VCXO connected to I/P A2 and the capacitance diode. Thus the frequencies of different units can be locked and AF frequency drift eliminated. The frequency control voltage can be measured at the socket marked RX SYNC. The 7.68 MHz quartz oscillator signal is fed via an isolating amplifier and O/P A30/C30 to the CONTROL BUS and is available for use by the other units.

The quartz signal is also shaped to a squarewave and divided down to 16 kHz before being applied to the transmitter and receiver synthesizers. The 16 kHz signal can be checked at the test sockets on the front-plate.

PLL SYNTHESIZER:

A frequency and phase-selective phase comparator compares the 16 kHz reference oscillator signal with the frequency, following division, of the VCO (voltage controlled oscillator). The voltage at the O/P of the phase comparator is used to correct the frequency of the VCO. The VCO voltage can be checked at the socked marked TX VCO.

The VCO generates a signal in the range 5 to 10 MHz. This carrier is available from O/P A12/C12 at twice the frequency as a push-pull signal 2TXFC for use by the transmitter RF converter P4LF. This carrier can be checked at the test socket TXFC.

The receiver PLL synthesizer functions in a similar manner. The push-pull signal of twice the frequency 2RXFC is available at O/P A20/C20 for use by converter P4LD/E. The signals RXFC and RX VCO can also be checked at sockets on the frontplate.

The programming and tuning of the P4LG unit are described in tuning instructions 5HYN589097-TA in the supplementary document .


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5.4 40 W power amplifier section

See block diagram 5HYN589137-CA of the 40 W power amplifier section in Appendix A.2.

The power amplifier P1LA, the transmitter filter E5LA/B, the RF hybrid P3LA and the auxiliary supply unit B5LA/C, which are described in Section 5.4, are accommodated in equipment rack P7LA.

Power amplifier P1LA

The channel 1 and channel 2 O/P signal from the transmitter RF converter P4LF is connected by the leads TXRF12-A and TXRF12-B from connector X184 to the I/P transformer of the power amplifier P1LA. In the case of three and four-channel schemes, the signals from channels 3 and 4 are also connected to the I/P of the power amplifier by the leads TXRF34-A and TXRF34-B.

The RF signal then passes through the AGC amplifier and pre-amplifier stages to the driver circuit. The gain of the AGC amplifier is determined by the emitter current of the O/P power transistors, which is thus protected against overload. A combined current/voltage regulation ensures a minimum of distortion due to non-linearity and also a constant O/P impedance. The driver circuit provides the low source impedance necessary for the correct operation of the O/P amplifier stage. The signal amplified by the push-pull O/P stage is combined again in the O/P transformer, from which it goes to the high-power transmitter filter E5LA or E5LB.

The forwards O/P current CFB and forwards O/P voltage VFB are added in the directional coupler and fed to the supervision circuit, which also monitors the auxiliary supply. Should either the auxiliary supply voltage or the O/P power fall below a prescribed minimum value, the latter of the two being adjustable, the Tx alarm is activated and transferred by an opto-coupler to the pilot and supervision unit P4LA.

The auxiliary supply for the power amplifier is provided either from the station battery or a secure AC supply via the series regulator (I/P X107/110). A supplementary circuit conditions the auxiliary supply for the driver circuit. The bias circuit supplies the quiescent current for the transistors of the O/P stage via the driver transformer.

The high voltage withstand I/P and O/P transformers provide the DC isolation of the power amplifier from the other parts of the equipment. This simplifies the connection of the battery for the auxiliary supply and avoids the need of a high-power DC/DC converter. The jumper positions for the different operating modes of the power amplifier P1LA can be seen from the table on the block diagram 5HYN589137-CA (see also Alternative programming 5HYN589096-TA).

Transmitter filter E5LA/B

Purposes of the filter:

- The transmitter filter reduces spurious emissions due to non-linearity of the O/P amplifier.

- The filter's high impedance in the rejection part of its characteristic enables further PLC units to be connected in parallel with only low losses.

- The transmitter filter protects the O/P amplifier from voltage spikes on the power line caused by power system switching, faults and lightning.


5 - 12 5HYN589126-TA

The transmitter signal from O/P amplifier P1LA is looped through the hybrid from pins B/D/Z30 and B/D/Z32 to B/D/Z28 and B/D/Z26 of X182 from where it goes to connectors X174 and X171 and the programmable transmitter filter. The impedance is transformed additionally by transformers T3 and T4 on the hybrid to double the bandwidth for three and four-channel operation.

The transmitter filter is designed for programming on site. The centre frequency of the filter can be set in steps of 2 kHz using the four sets of condensers C11-C15, C16-C18, C21-C25 and C26-C28, which are housed in two metal containers. Fine tuning is achieved with the aid of the coils L1 and L2. Filter E5LA is suitable for a range of 100 kHz to 500 kHz and filter E5LB for a range of 24 kHz to 100 kHz. Tuning is per-formed in conjunction with the tuning adapters P3LL and P4LM. Adapter P3LL is inserted in place of the hy-brid and contains switching and measuring facilities for tuning the circuits individually and for checking se-lectivity.

Programming and tuning the transmitter filter is described in detail in the Tuning instructions 5HYN589140-TA in the supplementary document.

RF hybrid P3LA

The purpose of the RF hybrid is to decouple the receiver from its own transmitter. Its use is essential where line attenuation is high, especially when transmitter and receiver bands are close together. The transmitter intermodulation products at the receiver I/P are correspondingly reduced by the transhybrid attenuation.

The module consists essentially of a transformer and tuned circuit, which form a model of the transmission line impedance. The high ratio of the transformer results in a low insertion loss between the transmitter and the line. The achievable level of attenuation between transmitter and receiver depends on the accuracy of the line model.

The O/P signal from the power amplifier is looped from I/P B/D/Z30 through the matching transformer T4 to O/P B/D/Z28 and the transmitter filter. The transmitter signal goes from I/P B/D/Z16 to a second matching transformer T3, the hybrid transformer T1 to the O/P B/D/Z20 and thence to the RF connector X175 marked RF LINE. The O/P impedance can be set to either 125 or 75 Ohms with the aid of soldered jumpers. The matching transformers T3 and T4 double the bandwidth of the transmitter filter for three and four-channel operation. The transmitter level can be measured at the test socket RF LINE. A measured level of 0 dBU corresponds to an O/P power of 10 W or +40 dBm.

The receiver signal from the RF connector passes via the hybrid transformer T1 to the receiver potentiome-ter. The gain of the receiver is set such that the AGC amplifier on P4LC is at its nominal operating point. The receiver signals RXRF-A and RX-RF-B go from O/P B12/D12 to the receiver RF converter P4LD/E.

Alarm conditions of the power amplifier P1LA are also evaluated on this unit. A TX ALARM is fed into the unit at I/P Z8, is signalled by the LED marked TX ALARM and leaves the unit at O/P D6 and goes to the pilot and supervision unit P4LA.


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5.5 Pilot and supervision unit P4LA

See block diagram 5HYN589136-CA for the converter section of channel 1 in Appendix A.2.

The functions performed by this unit can be divided into two main groups:

- the pilot channel

comprising the function blocks PILOT TRANSMITTER/RECEIVER and the TEST TONE RECEIVER and

- the supervision section

comprising the blocks TEST TONE GENERATOR, REMOTE LOOP CONTROL, the supervision circuits WATCHDOG and AUXILIARY SUPPLY, the blocking logic BLOCKING CONTROL and the frontplate and external alarm signals.

The pilot channel functions are performed by a digital signal processor (DSP) and those in the supervision section by a microprocessor.

The pilot channel hardware comprises the signal processor with internal data and program memories, the A/D and D/A converters for analogue I/O signals and a number of digital I/P and O/P modules. There are also circuits for controlling the serial ports, the I/O stages for exchanging analogue signals with other units and the programming switches for setting the parameters of the DSP.

The supervision hardware includes the 8 bit microcontroller with an internal data memory, an external pro-gram memory and the various I/P modules for data and clock signals. The test tone generator is an inde-pendent module. This unit also includes further supervision circuits, a number of signals and relays for external alarms.

5.5.1 Pilot channel

PILOT CHANNEL TRANSMITTER:

The M-WIRE signal coming from the telephony interfaces O4LB/C/D reaches the signal processor via I/P C31 and the function blocks of the supervision section connected to it. The supervision section controls the blocking of the M-WIRE signal line and the injection of the information needed for switching to the REMOTE LOOP mode. The signal processor performs the following functions:

- generation of the pilot frequency, which is keyed by the M-WIRE criterion - filtering of the keying spectrum - conversion of the modulated signal to the RF frequency of the channel followed by low-pass filtering.

The pilot signal undergoes D/A conversion and smoothing and leaves the unit as TX PILOT via the O/P stage and O/P pin C4, from where it proceeds to the AF converter P4LB.

The AF pilot signal at the O/P is monitored and should signal level fall by more than 6 dB with respect to its nominal level, the criterion TX PILOT FAIL is sent to the teleprotection unit NSD 50 and a transmitter alarm is issued. A transmitter alarm is also generated in the event of a failure of the O/P signal at the O/P of the final stage (TXRF-AL present at I/P C2).


5 - 14 5HYN589126-TA

PILOT CHANNEL RECEIVER:

The RX PILOT signal coming from the AF converter P4LB is connected to I/P A20, from where it goes via a limiter and an anti-aliasing filter to the receiver A/D converter.

The receiver signal passes through a channel filter before being converted to an IF, applied to a low-pass filter and then demodulated. There then follows a blocking stage, which enables defined blocking of the di-alling channel in the event of a failure. The E-WIRE criterion is connected from O/P A31 to the telephony in-terfaces O4LB/C/D.

The demodulated pilot signal also goes to the AGC block, where the AGC signal for controlling the gain is derived from it. The digital AGC signal is then converted to an analogue control voltage, smoothed and am-plified. The signal from the O/P amplifier goes to O/P C3 and thence to the controller of the AGC amplifier on P4LC.

The AGC voltage signal is blocked when the teleprotection unit NSD 50 generates a tripping signal. The AGC voltage is also kept constant for five seconds during transmission of a dialling signal and during severe disturbances and whenever the signal strength at the I/P of the receiver is too low.

The pilot signal is also used to monitor signal quality. To this end, it is compared with corresponding refer-ence levels in the blocks MIN RX LEVEL, SNR and BURST SNR. If the signal falls below these levels, the module BLOCKING CONTROL emits an alarm and the relevant internal and external circuits are blocked.

The synchronisation of slave receivers is also achieved by processing the pilot frequency. This takes place in the RX SYNC block, where the local pilot signal is compared with the pilot signal being received at the O/P of the channel filter. The control voltage VCXO obtained by phase comparison is converted to an analogue signal and amplified and passes via O/P A3 to the synthesizer P4LG. The VCXO signal voltage is held constant whenever the signal strength being received is too low, the SNR is too low or a dialling signal is being transmitted.

TEST TONE DETECTOR:

The DSP hardware of the test tone detector is the same and its different function is simply a matter of different software modules. The 1000 Hz service telephone call tone in the RX PILOT signal being received is detected by appropriate circuits (filter and level detector). After a delay of 3 seconds, this signal is relayed to the telephony interfaces O4LB/C/D via O/P C17 and also to the REMOTE LOOP CONTROL block, where it serves as criterion for initialising the remote loop.

5.5.2 Supervision section

Testing facilities and auxiliary functions

Apart from the actual supervision functions and the processing of alarm conditions, the supervision section also includes testing facilities and auxiliary functions for use when testing the equipment and during com-missioning.


5 - 15 5HYN589126-TA

TEST TONE GENERATOR:

The supervision section of the unit includes the separate hardware for the GENERATOR block, which per-forms the following:

- generation of the 1000 Hz call tone - generation of the 800 Hz and 3000 Hz test tones - PLL tracking filter used for the remote loop test when measuring the AF fre-

quency/amplitude characteristic.

In normal operation, the PLL circuit generates in conjunction with the 200 Hz reference frequency the 1000 Hz call tone when the call button on the frontplate is pressed, respectively the 800 Hz or 3000 Hz test signals when the changeover switch is operated. The test signals are available at test sockets on the front-plate. The 1000 Hz call tone is connected via O/P C6 to the AF converter P4LB for feeding into the trans-mitter circuit.

In the remote loop mode, the AF signal transmitted from the near end of the line is detected by the tracking filter of the equipment at the far end and looped to its transmitter via O/P C6 on P4LB to be returned to the near end equipment. The changeover to the remote loop mode is dependent on the RLC criterion, i.e. on the detection of the 1000 Hz call signal and the code initiating the remote loop mode transferred via the pilot channel.

REMOTE LOOP CONTROL:

This is a firmware module used with the supervision section, which controls and monitors the enabling, holding and disabling of the REMOTE LOOP TEST.

Enabling: Feeding an AF signal at 0 dBm0 into the AF converter P4LB and the subsequent transmission of the 1000 Hz test tone of longer than 3 seconds by pressing the call tone button result in the following:

Local station:

1. detection of the initialisation criterion SET REMOTE (I/P A5) 2. transmission of the REMOTE LOOP code 3. detection of the acknowledgement signal returned from the remote station and passing on the

REMOTE ON signal to the unit P4LB via O/P A6, where it causes the LED marked REMOTE ON to light

4. generation of the blocking signals LTC and TT 5. blocking of the AF signals and dialling channel at transmitter and receiver ends 6. lighting up of the LED marked WARN.

Remote station:

1. detection of the 1000 Hz test tone and the REMOTE LOOP code 2. transmission of the acknowledgement signal via the dialling channel (duration "1") 3. generation of the blocking signals LTC and TT 4. closing of the remote loop in accordance with RLC 5. blocking of the AF signals and dialling channel at transmitter and receiver ends 6. lighting up of the LED marked WARN.


5 - 16 5HYN589126-TA

Conditions for holding the remote loop circuit:

- The cyclic code is being received by the remote station. - The acknowledgement signal is being received by the local station.

Disabling the remote loop test:

Removing the cable feeding in the signal at the local station causes:

1. discontinuation of transmission of the code 2. resetting of the REMOTE ON signal 3. extinction of the LED signals REMOTE ON and WARN in both stations 4. resetting of the acknowledgement signal in the remote station 5. opening of the remote loop at the remote end 6. cancellation of the blocking of AF signals and dialling channel in both stations.

Supervision and alarm functions

AUXILIARY SUPPLY

Hardware monitors in this section of the unit monitor the ±12.8 V and +5.1 V supplies from the DC/DC con-verter B4LA. The PSU criterion is generated should a voltage exceed or fall below its permissible limits. In this case the frontplate LED signal SUP extinguishes, the signal processor and microcontroller are reset and a number of circuits are blocked and auxiliary alarm relays activated (reset) by the BLOCKING CONTROL block.

WATCHDOG

These two functions monitor the signal processor and microcontroller hardware. Should a defect be de-tected, i.e. either the criterion DSP or MC is being generated, the LED on P4LA lights to give alarm. A DSP alarm initiates the same precautions as a SUPPLY alarm.

TX ALARM

Both the AF pilot and the RF transmitter signal are monitored at the transmitter end. The two criteria PILOT FAIL and TXRF-AL are combined to become the alarm criterion TX, which after a delay is signalled by the LED marked TX and fed to the BLOCKING CONTROL logic for evaluation. An optional block called SELECTIVE SUPERVISION is available for separately monitoring the RF pilot, which part of the TX-RF signal applied to I/P A2. Used for this purpose, the signal TXRF1 at the O/P of this block is interlinked with the alarm criterion PILOT FAIL.

CARRIER SUPERVISION

A further option is the TX/RX CARRIER function block for monitoring the carrier signals at both transmitter and receiver ends, which is controlled via the I/P's C7 and C8. The clock frequency for its signal processor and microcontroller is obtained from the 7.68 MHz quartz local oscillator. In the event of a failure of the cen-tral clock, there is a stand-by clock generator, which enables the microcontroller to continue processing the program and the supervision section to remain in operation.


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BLOCKING CONTROL

This firmware of this block processes a large number of external and internal unit status and alarm criteria. According to the signals at the I/P's of the block, the control and blocking signals necessary are generated and frontplate and external alarms activated, the latter by means of the auxiliary relays.

Table 5.1 summarises the logical relationships between the I/P's and O/P's of the BLOCKING CONTROL module and the conditions leading to alarms and the blocking of other functional units.


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K2, K3, K4 = Optional

Table 5.1 Blocking control alarm logic


5 - 19 5HYN589126-TA

Definitions of the alarm logic I/P's and O/P's used in Table 5.1

External I/P's:

Internal I/P's:

LOCAL LOOP active when the ETL is set to

local TX-RX loop, i.e. when the

dummy load is plugged in.

PLUG-OUT 1 active when one of the basic ETL

units is not inserted.

AGC BLOCKING active when NSD 50 is receiving

a tripping signal, i.e. AGC blocked.

WARNING low priority alarm initiated by

certain ETL units (e.g. digital

transit filter E1LA or aux. supply

failure with redundant supply units)

AF COMMON general alarm initiated by

certain ETL units.

TX CARRIER TX carrier supervision alarm (option)

RX CARRIER RX carrier supervision alarm (option)

PILOT SWITCH blocks TX ALARM when NSD 50

transmits a tripping signal and

during the NSD 50 loop test.

LTC active in the local station

during a remote loop test.

RLC active in the remote

station after receiving a

correct remote loop code.

DSP active for a failure of

the signal processor in

the pilot block.

TT active during transmission

or receipt of the test tone.

PSU active when the auxiliary

supply supervision picks up.

DSPW active for a DPS software

error.

RXL receiver alarm, signal

strength

at receiver too low.

FAST burst interference alarm (BURST SNR)

SNR active when signal-to-noise ratio

(SNR) of received signal to low.

TX-IN transmitter alarm

(combined Tx alarms)

MC active for a microprocessor

failure

.

(The O/P's are active under the conditions given in the blocking control alarm logic of Table 5.1.)

External O/P's:

Internal O/P's:

TXB interrupts the useful AF

transmitter signals in the

remote loop mode.

Exception: NSD 50 trip signal

TRY TX/RX ready signal processed

by NSD 50.

SLOW MUTE blocks the AF O/P's of the

AF converter, telecontrol and

telephony interfaces

Exception: NSD 50

FAST MUTE blocks selected telecontrol

O/P's when the burst SNR

alarm picks up.

PAX blocks the telephone

BLOCKING exchange.

K1 CABINET ALARM: This is a general

alarm activated by all COMMON

ALARM and WARNING signals.

The relay is normally energised

and closes its alarm contact

when it resets.

K2* 1 potentially-free C/O contact each

for TX ALARM and COMMON ALARM.

K3* 1 potentially-free C/O contact each

for RX ALARM and COMMON ALARM.

K4* BURST SNR or WARNING: 1 potentially-

free C/O contact used as programmed

for fast blocking of data channels or

remote signalling of WARNING

conditions (optional).

LED low priority alarm

WARN combination of external low

priority alarms with the

internal criteria given in

the alarm logic table.

AGCB blocks the AGC

SB SIGNALLING BLOCKING: blocks

dialling I/P's and O/P's without

changing current status.

SOF SIGNALLING OFF: enables the

dialling channel.

TX transmitter alarm, internal

criterion.

* Optional


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The following LED's on the frontplate signal alarm conditions and operating statuses:

COM general alarm red WARNING low priority alarm yellow TX transmitter alarm red RX receiver alarm red SNR SNR alarm red P4LA watchdog (processor failure) red SUP auxiliary supply intact green

In normal operation the seven-segment LCD shows the AGC status (remaining gain available, normally 26 dB). Pressing the test tone button when a failure is being signalled causes a fault code with further infor-mation on the fault to be shown on the LCD. (The table of alarm codes is given in Section 2.2.6).

Four auxiliary relays K1 ... K4* with potentially-free contacts are provided for remotely signalling alarms:

K1: cabinet alarm N/C contact K2: Tx alarm C/O contact K2/K3*: combined transmitter/receiver alarm (general alarm) C/O contact K3*: receiver alarm K4*: optional noise burst/low priority alarm C/O contact

A summary of the criteria monitored, resulting action in the units, the alarm and status signals and externally signalled alarms is to be found in Section 2.2.6 "Supervision and alarm facilities".

* optional


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5.6 Synchronising receivers

The slightest frequency shift between transmitter and receiver when operating narrow band frequency shift keyed (FSK) channels cause isochronous distortion of the demodulated data signal. This can be avoided by synchronised demodulation by the slave receiver. Automatic synchronisation of a PLC transmitter/receiver pair results in zero frequency shift of AF signals.

The operation of the carrier frequency scheme and receiver synchronisation in the slave station is illustrated in the diagram below.

Fig. 5.3 Carrier scheme and receiver synchronisation


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The quartz oscillator in the ETL equipment at the master end is free running. From it are derived all the internal carriers (local oscillator frequencies) and clock frequencies needed. Its pilot is transmitted to the slave equipment at the opposite end of the line, where it is used as reference frequency for synchronisation.

The AF signal RX PILOT goes from the O/P of the AF converter P4LB to the pilot and supervision unit P4LA, where it is filtered to become the received pilot signal and compared in a phase comparator with a local pilot signal. The phase comparator produces a control voltage VCXO for controlling the frequency of the quartz local oscillator on the synthesizer unit P4LG of the slave equipment. Since in the steady-state condition, the oscillator of the remote master and the oscillator of the local slave are synchronised at the same frequency, the carriers used to obtain the IF's in both units are also synchronised. This sychronisation prevails regardless of whether data is being transmitted from master to slave or from slave to master. In duplex operation, a synchronisation signal is only needed in the direction from master to slave.

An ETL terminal is programmed to be master or slave by appropriately inserting the jumpers MA and MB, respectively SA and SB on the carrier synthesizer unit P4LG.

It is possible to operate two master stations asynchronously. If, however, a maximum permissible frequency shift of 2 Hz is specified, this mode of operation is limited to 200 kHz. The operation of two units in the slave mode is not possible.


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5.7 Telephony interfaces

5.7.1 2/4-wire PAX interface O4LC

Refer to block diagram 5HYN589134-CA in Appendix A.2.

The unit O4LC is an interface for connecting two or four-wire speech signals and associated signalling criteria to exchange equipment. It includes all the function blocks needed for processing transmitter and receiver speech signals and signalling criteria. Further circuits enable a four-wire service telephone to be connected. The following description of the operation is with reference to the block diagram.

The transmitter speech signal in four-wire operation reaches the I/P amplifier via the DC isolated I/P A6/C6 marked 4 WIRE INPUT. The I/P amplifier adjusts the interface level to that required internally. The signal is then routed via the 300 Hz high-pass filter, either through or around the switchable compressor, the limiter circuit and programmable low-pass speech filter to O/P C13, from where it is conducted by the ETL bus to the AF converter P4LB. Receiver signals are connected to I/P X1 A20. From X1 A20 they go to the programmable low-pass filter, which separates the speech signals from the superimposed telecontrol signals. They then either pass through or by-pass the switchable expander and are adjusted in level by the amplifier which follows. The O/P signal is available at the four-wire DC isolated O/P A8/C8 marked 4 WIRE OUTPUT.

A two-wire exchange is connected to the speech interface at the I/O A2/C2 marked 2 WIRE and to trans-mitter and receiver channels via a switchable AF hybrid. Programming switches are provided for setting the gains in transmitter and receiver channels, which enable the interface levels for two and four-wire operation to be matched within a wide range.

The synthesizer SYNT can be programmed using plug-in jumpers and provides the clock frequencies needed for setting the limit frequencies of the transmitter and receiver switched-capacitor (SC) low-pass fil-ters.

The signalling and control criteria are transferred by opto-couplers. However, the opto-coupler circuits are only fully DC isolated when using an optional DC/DC converter. The dialling signals for transmission are connected to the I/P marked TELEPHONE SIGNALLING M and those which are received are passed on by the interface unit from its O/P marked TELEPHONE SIGNALLING E. The dialling impulses can be inverted with the aid of the jumpers TC, TD, RC and RD. The "BUSY" LED lights when the M-WIRE and/or E-WIRE are active.

The control signals "HYBRID" and "SPEECH CONTROL" supplied by the exchange equipment are needed for switching from two to four-wire operation, respectively from local to transit operation. In two-wire opera-tion, the "HYBRID" signal switches the AF hybrid into operation. If at the same time the "SPEECH CONTROL" contact is open, the transmitter and receiver gains are switched for two-wire operation. The hybrid is switched off and the gains set for local four-wire operation, when "HYBRID" and "SPEECH CONTROL" contacts are both open.

Trunk lines are relayed on a four-wire basis and the "SPEECH CONTROL" contact is closed to set the gain for transit operation.

For those applications requiring the compander (jumper CX), the compander is switched out of circuit when the "SPEECH CONTROL" contact is closed and in circuit when it is open (terminal station of a trunk line).


5 - 24 5HYN589126-TA

The receiver is blocked by the signal SLOW MUTE connected to I/P C18, when the quality or strength of the signal being received is too low. The speech O/P is similarly blocked (I/P A9) by a tripping signal from the NSD 50. During one of the alarm conditions according to Table 5.1 or when the service telephone is being used (jumper PB), the exchange equipment is blocked by the signal PAX BLOCKING, which is applied to O/P A20/C20 by a potentially-free contact.

The settings for the various operating modes of O4LC are described in Alternative programming 5HYN589096-TA.

Service telephone:

The standard unit makes provision for inserting a four-wire Microtel Type Q8AA into the frontplate (4-pin socket marked MICROTEL). The 1000 Hz call tone is transmitted when the CALL button is pressed. At the receiver end of the line, the 1000 Hz call tone is detected on P4LA, which operates the buzzer on O4LC via its I/P C17.

Using the isolating amplifier in the service telephone receiver circuit and the Microtel, it is possible to quickly check the general condition of VFT channels and test tones acoustically without instruments. The corresponding signal is injected at the sockets marked AUDIO on the frontplate.


5 - 25 5HYN589126-TA

5.7.2 4-wire PAX interface O4LB


The unit O4LB is an interface for connecting four-wire speech signals and the associated signalling criteria to exchange equipment and includes all the function blocks needed for transmitting and receiving them. Further circuits enable a four-wire service telephone to be connected. The following description of the oper-ation is with reference to the block diagram.

The transmitter speech signal reaches the I/P amplifier via the DC isolated I/P A6/C6 marked 4 WIRE INPUT. The I/P amplifier adjusts the interface level to that required internally. The signal is then routed via the 300 Hz high-pass filter, either through or around the switchable compressor, the limiter circuit and programmable low-pass speech filter to O/P C13, from where it is conducted by the ETL bus to the AF converter P4LB. Receiver signals are connected to I/P X1 A20. From X1 A20 they go to the programmable low-pass filter, which separates the speech signals from the superimposed telecontrol signals. They then either pass through or by-pass the switchable expander and are adjusted in level by the amplifier which follows. The O/P signal is available at the four-wire DC isolated O/P A8/C8 marked 4 WIRE OUTPUT.

Programming switches are provided for setting the gains in transmitter and receiver channels, which enable the four-wire interface level to be adjusted within a wide range.

The synthesizer SYNT provides the clock frequencies needed for setting the limit frequencies of the switched-capacitor (SC) low-pass filters in transmitter and receiver.

The signalling and control criteria are transferred by opto-couplers. However, the opto-coupler circuits are only fully DC isolated when using an optional DC/DC converter. The dialling signals for transmission are connected to the I/P marked TELEPHONE SIGNALLING M and those which are received are passed on by the interface unit from its O/P marked TELEPHONE SIGNALLING E. The dialling impulses can be inverted with the aid of the jumpers TC, TD, RC and RD. The "BUSY" LED lights when the M-WIRE and/or E-WIRE are active.

The control signal SPEECH CONTROL provided by the exchange equipment is required for switching from local to transit operation.

Where in the repeater mode trunk lines are linked by four wires, the compander is switched out of circuit when the "SPEECH CONTROL" contact is closed (jumper CX) and in circuit when it is open (terminal station of a trunk line).

The receiver is blocked by the signal SLOW MUTE connected to I/P C18, when the quality or strength of the signal being received is too low. The speech O/P is similarly blocked (I/P A9) by a tripping signal from the NSD 50. During one of the alarm conditions according to Table 5.1 or when the service telephone is being used (jumper PB), the exchange equipment is blocked by the signal PAX BLOCKING, which is applied to O/P A20/C20 by a potentially-free contact.

The settings for the various operating modes of O4LB are described in Alternative programming 5HYN589096-TA.


5 - 26 5HYN589126-TA

Service telephone:

The standard unit makes provision for inserting a four-wire Microtel Type Q8AA into the frontplate (4-pin socket marked MICROTEL). The 1000 Hz call tone is transmitted when the CALL button is pressed. At the receiver end of the line, the 1000 Hz call tone is detected on P4LA, which operates the buzzer on O4LB via its I/P C17.

Using the isolating amplifier in the service telephone receiver circuit and the Microtel, it is possible to quickly check the general condition of VFT channels and test tones acoustically without instruments. The corresponding signal is injected at the sockets marked AUDIO on the frontplate.


5 - 27 5HYN589126-TA

5.8 Telecontrol interfaces


5.8.1 Telecontrol interface O4LA

O4LA is an interface for connecting modems and VFT channels. The transmitter section is provided with three balanced, DC isolated I/P's. Each of these can be switched by jumpers to either the disconnectable bus TXAF-D or the non-disconnectable bus TXAF-ND. The receiver section is similarly equipped with three balanced, DC isolated O/P's for AF signals. With the aid of jumpers, each of these O/P's can be set to one of the following operating modes:

- broadband 300 Hz to 3850 Hz (standard) - low-pass 300 Hz to 3600 Hz (Option fitted to P4LB) - transit filter selectable frequency band (option fitted to O4LA)

The principle of operation is explained with reference to the block diagram. From either INPUT 1, 2 or 3, the AF signals go to the protection and matching I/P circuit comprising attenuation components and the I/P transformer. The gain of the interface is adjusted by the amplifier that follows to the internal level of -10 dBr. The gain is set on programming switches in steps of 0.25 dB. The telecontrol I/P's can be connected to ei-ther the disconnectable bus TXAF-D or the non-disconnectable bus TXAF-ND with the aid of the jumpers TB, TD and TF, respectively TA, TC and TE.

Normally the "broadband" receiver signal RXAF-3K85 at I/P A20 comes from the AF converter P4LB and passes via the isolating amplifier to one or more of the balanced, DC isolated telecontrol O/P's OUTPUT 1, 2 and 3, depending on the positions of the jumpers RA, RD and RG. Their output levels are set individually on the O/P amplifiers. Where the optional hybrid (3.6 kHz low-pass filter) on P4LB is being used and the appropriate settings have been made, the receiver signal RXAF-3K6 is taken from I/P A18. When the entire AF band is being repeated (transit mode), the standard 3780 Hz pilot is suppressed.

The analogue switches in the telecontrol O/P's enable the O/P's to be blocked by the receiver alarm signal. In the cases of OUTPUT 1 and 2, muting is determined by the SLOW MUTE signal from P4LA. OUTPUT 3 can be muted either by SLOW MUTE or FAST MUTE (BURST SNR), depending on whether the jumper is in position RM or RL.

Fail-safe, ESD protected test sockets are provided on the frontplate for setting the gain and checking the transmitter telecontrol signals. All telecontrol I/O/P's are equipped with plug-in jumpers for measurement and isolating purposes.

The programmable transit filter E1LA (option) mounted on the sub-module is normally used in the receiver circuit (jumpers TG and RI and any combination of RC, RF and RK). Alternatively, the filter can be con-nected in I/P INPUT 2 of the transmitter circuit with the aid of jumpers TI and TH. The digital transit filter has a WARNING alarm O/P, which is energised in the event of software failures, for which the filter can still operate, and also when the unit has been incorrectly set. A COMMON ALARM is generated for soft and hardware faults, which impair the correct operation of the filter. Alarms of this kind are signalled by the LED "FAIL". Both general alarms and low priority alarms go to the unit P4LA for evaluation. A green LED on the frontplate of O4LA shows that the unit is intact and operating normally.


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5.8.2 Digital transit filter E1LA

The purpose of the transit filter is to selectively loop one or several data channels in the AF band from 360 Hz to 3720 Hz from one PLC equipment to another. Coefficients of standard filters stored in EPROM's enable the characteristics of all bandpass filters in the AF range to be achieved in steps of 60 Hz. Four BCD switches are provided for independently setting the upper and lower limits of the filter band. This group of standard filters is not equipped with equalizers for delay distortion. Provision is made, however, for selecting one of 10 special filters from a second group, which are equipped with equalizers. Since the filter characteristics are determined by the firmware in the EPROM's, other special filters can be implemented without difficulty.

The basic operation and possible settings can be seen from the diagram below. Instructions for program-ming the transit filter are contained in Alternative programming 5HYN589096-TA.

Fig. 5.4 Programmable transit filter E1LA Programming the bandpass range in steps of 60 Hz


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The basic operating principle of the digital transit filter is explained with reference to the block diagram of Fig. 5.5. The analogue signal at I/P 8/9 passes via the I/P amplifier and anti-aliasing filter to the sample and hold block, where it is sampled at a rate of 11.62 kHz. The O/P signal from this block then proceeds to the 12 Bit A/D converter and then to the signal processor, which filters it in accordance with the filter program stored in the EPROM. The output of the filter for the various samples is converted back to an analogue sig-nal by the D/A converter. The level of the analogue signal is then adjusted and the signal smoothed before its O/P impedance is appropriately matched by an emitter follower and it made available at O/P 11/12.

The clock frequencies needed for the processor, the A/D and D/A converters and the supervision facilities are generated on the unit itself by a quartz oscillator and frequency divider.

All the software is stored in the EPROM (filter routines and coefficients and test routines).

The filter characteristic and functions are selected using rotary switches A, B, C and D. The memory address of the filter selected is applied to the I/P port via "latches". The corresponding set of filter coefficients is then loaded into the RAM of the signal processor.

Fig. 5.5 Block diagram of the digital transit filter E1LA


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The O/P port is used to control the analogue switch, for external alarms and for the frontplate LED's. The transit filter is equipped with two alarm O/P's and four alarm and status LED signals. Should a defect occur, which does not impair the operation of the filter, a low priority alarm (WARNING) is generated and signalled by the corresponding LED. If the filter can no longer function, it isolates itself from the bus and both WARNING and AF COMMON alarms are generated.

High reliability is achieved by comprehensive monitoring of hard and software.

A watchdog continuously supervises the hardware and checks that the O/P port is activated for each sam-ple. Should this not be the case, the alarms AF COMMON and WARNING are set following a delay and the processor is reset. A processor failure is signalled by the LED marked PROCESSOR.

The selected set of filter coefficients is monitored cyclically during operation and corrected if necessary or, where correction is not possible, signalled by the LED marked PARITY on the frontplate and remotely as a low priority or urgent alarm. Invalid combinations of switch positions when selecting the filter characteristic are indicated by the LED marked SWITCH.

Routines are included, which facilitate testing, commissioning and fault-finding. Three different test routines can be selected using the same switches used for selecting the filter characteristic.

The test routine "PARITY" calculates a check sum for the entire contents of the EPROM. The LED marked PARITY lights up and a low priority WARNING alarm is generated, should the result not agree with the stored value.

The LOOP TEST routine loops the O/P analogue switches to the I/P. A test tone is then generated and in-jected into the loop. If the discrepancy exceeds a given reference value, the fact is indicated by the lighting of the LED marked LOOP.

A programmable synthesizer is accessed by the test routine "SYNTH", which generates all the signals re-quired during commissioning and obviates the need of an external signal generator.

5.9 NSK 5 operation

Provision is made for directly inserting the programmable modem NSK 5 into the channel rack P7LB in the same way as the other AF interfaces. Since a separate equipment rack and auxiliary supply can be avoided, this is a cheap method of setting up a telecontrol system. The space available for the NSK 5 modem depends on the ETL version in use (see Section 7 "Alternative versions"). If the ETL is equipped with the redundant auxiliary supply unit B4LB, but does not have an NSD 50, up to five NSK 5's can be accommodated (module Type G4AE) in the channel rack P7LB. Only four NSK 5 modems, however, can be fitted in the case of the single auxiliary supply unit B4LA.

The modems are supplied from the internal ±12.8 V. The transmitter AF signals are connected to the disconnectable bus TXAF-D. The receiver AF signal is taken from the broadband bus RXAF-3K85. A COMMON ALARM generated by the NSK 5 is connected to the ETL alarm bus and thus to the P4LA, where it activates the corresponding signals. When operating in conjunction with ETL, access to the serial interface of NSK 5 is achieved by inserting a standard V9LA interface cable into the connector at the rear. The modem can also be accessed for testing and measurement purposed via the 25 pin Sub-D connector on the front.


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The interconnections between the NSK 5 modem G4AE and ETL can be seen from Fig. 5.6.

Fig. 5.6 Interconnections between the NSK 5 modem G4AE and ETL

The main features of the G4AE modem, which is designed for use with the ETL, are given below. More de-tailed information can be obtained from the Operating instructions NSK 5, 5HYN589143-TA.

- The G4AE is a fully programmable VFT channel with DIL switch settings for baud rate, transmitter and receiver frequencies and gain.


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- All channels and baud rates conforming to CCITT R.35, R.37, R.38A and R.38B can be programmed. In order to make the best use of the available AF bandwidth, the 100 and 200 Bd channels can be set in steps of 120 Hz. The 480 Hz wide 200 Bd channels can also be operated 1.5 times faster at 300 Bd.

The following additional operating modes are possible in conjunction with the ETL:

- max. three 600 Bd channels. The channel centre frequencies of 1320 Hz and 2760 Hz used on the NSK 4 can also be set.

- a 1200 Bd channel above the 2000 Hz speech channel or combined with other data chan-nels at lower frequencies.

- a 1200 Bd channel according to CCITT V.23

- a 2400 Bd channel

Frequency bands assigned to pilot channels cannot be used for data transmission. The hatched frequency ranges may be used by channels of correspondingly lower baud rates. The permissible allocation of channels is shown in Fig. 2.1.

- All the functions are included on a single PCB (6U/220 mm, width 6R, see Fig. 5.7 for front view).

- The modem can operate together with the former VFT channels NSK 3, NSK 4, NSK 23 and NSK 35.

- The unit includes a sychronising facility and a data regenerator for reducing isochronous distortion, as also a delay distortion equalizer for operation at 2400 Bd.

- serial data interface conforming to CCITT V.24, V.28, V.10 with access from the front for test purposes.

- The modem is DC isolated from the ETL equipment.

- The unit fulfils the EMC requirements stipulated by the telephone companies, DBP and IEC.

The following testing and measuring facilities are included:

- local loop test initiated by a test button on the frontplate or by the data terminal equipment applying the corresponding control signal to the serial interface.

- transmission test for checking the bit failure rate of the entire channel initiated by a test switch on the frontplate.

There are LED signals for the most important I/O signals on the frontplate.


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Fig. 5.7 Front view of modem Type G4AE


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5.10 Teleprotection device Type NSD 50

The teleprotection device NSD 50 is only used in conjunction with the PLC equipment Type ETL. It com-prises a maximum of three plug-in units, which are inserted at the locations reserved for them in the PLC equipment rack (see Fig. 5.8).

The smallest NSD 50 has two plug-in units and can transmit two independent tripping signals, which are sufficient in most cases to protect a transmission line. The system can be expanded to handle four tripping signals by simply inserting an additional relay interface. Totally, there are then two permissive and two direct transfer tripping signals available, the latter having priority. Equipped with the maximum of four tripping signals per PLC link, two PLC links, for example, are able to accommodate first and second main protections for a double circuit line.

The normal arrangement is for the NSD 50 to use the ETL pilot together with the ETL instead of having one of its own. The pilot is continuously monitored at the receiver end and alarm given in the case of inadequate signal quality (SNR or strength).

In the event of a fault on the protected line, the NSD 50 interrupts the pilot and transmits a tripping signal in the PLC speech band. The interruption of the speech signals and the superimposed interruptible data chan-nels and the boosting of the power to the maximum available are controlled by appropriate signals from the NSD 50 to the P4LB unit in the ETL equipment.

When an NSD 50 receiver detects that the pilot has disappeared and a correct tripping signal of sufficient quality is being received instead, the tripping signal is relayed to the corresponding O/P. If pilot and tripping signals are either both being received, or are both missing at the same time, an alarm is given and, in the latter case, the unblocking O/P contacts close for 200 ms.

A number of speech band frequencies are provided for the various tripping signals and combinations of tripping signals. Depending on the particular protection scheme (permissive or direct transfer tripping), the frequencies are used or allocated differently (see Operating instructions 5HYN589142-TA).

By using the ETL pilot signal as the guard signal for the NSD 50 and transmitting tripping signals via the speech channel, the NSD 50 does not need any additional PLC bandwidth.


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Frontplate signals: "AL" General alarm (red) This LED lights on all units effected by an alarm condition. "RDY" Ready (stand-by) (green) The "Transceiver ready" (TRY) signal from the Type ETL PLC equipment is active. "TRP" Trip (green) The speech band tripping signal receiver has picked up. "GRD" Guard (green) Lights whenever the pilot signal is being received. "SNR" Signal-to-noise ratio (red) Lights when SNR too low. "LEV" Level alarm (red) Pilot signal strength out of permissible limits. "TxA" ... "TxD" (green) Lights when a tripping signal is being transmitted. "RxA" ... "RxD" (green) Lights when a tripping signal is being received. "TxA/B", "TxC/D" (7 segment LCD) No. of tripping signals transmitted (00 ... 99). "RxA/B", "RxC/D" (7 segment LCD) No. of tripping signals received (00 ... 99). Controls: "LOOP TEST" (black pushbutton) Manual loop test initialisation "RESET" (red pushbutton) Reinitialisation of the signal processor (O/P's blocked for about 10 s) "Tx" Signal transmitted by NSD 50 (0.3 ... 4 kHz, 0 dBr) "Rx" Signal received from ETL (0.3 ... 4 kHz, 0 dBr) "COM1" Standard serial interface for connecting a control terminal. "DISPLAY" Switch for switching the LCD between command A and B, respectively C and D.

"RESET COUNTER" (black pushbutton) Trip signal counter reset button

Fig. 5.8 Front view of the teleprotection device Type NSD 50


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Interface between the teleprotection device NSD 50 and the ETL PLC equipment

All the connections needed to transfer signals between NSD 50 and the ETL are established by the buses ETL-BUS1 and ETL-BUS2 on the back plane of the equipment rack. No other leads or cables between the two are required (see block diagrams 5HYN589136-CA for the converter section of channel 1 in Appendix A2 and 5HYN589139-CA for the back plane PCB of the channel rack P7LB in Appendix A3).

The interconnections between ETL and NSD 50 can be seen from Fig. 5.9.

Fig. 5.9 Interconnections between ETL and NSD 50

To transmit a tripping signal, the NSD 50 emits a signal via the uninterruptible connection TX-AF to I/P C11 of P4LB.

A number of signals from the teleprotection device NSD 50 control the status of the BOOST LOGIC block on P4LB, which accordingly issues the interrupt and PLC boost instructions. These briefly interrupt the speech channels, pilot and those data channels, which are programmed as interruptible. The power of a tripping signal is then boosted to the maximum transmitter power available.


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The signals TX SPEECH OFF, PILOT SWITCH and BOOST generated by NSD 50, which are applied at the appropriate logic level to I/P's C9, A10 and C10 of the BOOST LOGIC block result in the following:

TX SPEECH OFF: generated by an NSD 50 start or NSD 50 tripping signal and interrupts the transmission of:

- speech signal TX SPEECH - transit signal AUX AFTX - TEST TONE during REMOTE LOOP

injection

TX PILOT SWITCH: generated by an NSD 50 tripping signal and interrupts

- transmitter pilot signal TX PILOT

BOOST: generated by an NSD 50 start or NSD 50 tripping signal and interrupts the transmission of:

- disconnectable TXAF-D channels - transit signal AUX AFTX - TEST TONE during REMOTE LOOP injection

sets the boost ratio for:

- NSD 50 tripping signal TX-AF - a tripping signal of an external

teleprotection unit to 0 dB

The BOOST LOGIC also takes into account the signal TXB, which is emitted by the unit P4LA following ini-tialisation of the remote loop mode and applied to I/P A7. Apart from the NSD 50 and pilot signals, it interrupts the transmission of all the AF signals and also blocks the auxiliary AF receiver O/P AUX. AF OUTPUT.

Remote loop operation is interrupted as soon as a teleprotection signal is generated.

At the remote station, the broadband signal received is conveyed to NSD 50 from the ETL via O/P C20 on P4LB by the interface connection "RX PILOT". Providing NSD 50 finds the signal to be a genuine tripping signal (no pilot and correct tripping signal tone in the speech band), the speech signals on units O4LB/C/D of the remote receiver are interrupted by the signal "Rx SPEECH OFF" and the AGC in the ETL is inhibited on the unit P4LA by the signal "AGC BLOCKING". Blocking the AGC prevents the receiver gain from being raised as soon as the pilot disappears in readiness for receiving a tripping signal.

In the case of a failure in the NSD 50, a "COMMON ALARM" is passed to the ETL via the correspondingly labelled connection.


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5.11 AF bus design

The internal communication between the various AF interfaces O4LA/B/C/D, NSK 5 (options) and the basic ETL units P4LA and P4LB takes place via the AF buses ETL-BUS1 and ETL-BUS2. The same buses also conduct the signals between the NSD 50 processor G4AA and the ETL. The NSD 50 processor module communicates with the teleprotection unit interfaces via two independent buses NSD50-BUS1 and NSD50-BUS2 on the back plane PCB (see block diagram 5HYN589139-CA for the back plane PCB of the channel rack P7LB).

The general design of the AF bus and the most important signals are shown in Fig. 5.10. Basically, any combination of up to five AF units can be accommodated in the P7LB equipment rack. This number is reduced to four or three when using the teleprotection device NSD 50.

Fig. 5.10 AF bus layout

5.12 Two-channel PLC equipment Type ETL42

See block diagrams Channel 2 carrier section, 5HYN589135-CA, Appendix A.2 and Channel 1 carrier section, 5HYN589136-CA, Appendix A.2

The basic ETL can be equipped for two-channel operation by adding a rack Type P7LB with the corre-sponding ancillary units. The AF functions, the conversion to the first IF and the supervision functions of channel 2 are identical to those of channel 1 (see description of the carrier frequency section P4LB in Sec-tion 5.2 and Sections 5.5 to 5.11). The modulation scheme for two-channel operation is described in Section 5.1.

The equipment racks for two-channel operation differ from those for one-channel operation in the following points:

Channel 1:

(see block diagram, 5HYN589136-CA, Appendix A.2)

- The channel 1 RX RF converter P4LD is replaced by the channel 2 RX RF converter P4LE.

- The remaining units are identical to one-channel operation.

Channel 2:

(see block diagram, 5HYN589135-CA, Appendix A.2)

- The TX RF converter P4LF and the RX RF converter P4LD are replaced by the channel link V9LK.

- The frequency synthesizer P4LG is replaced by the synthesizer P4LI.


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- The IF converter P4LC uses the 636 kHz and 156 kHz carriers from P4LI, which are shifted by 4 kHz.


The following Sections only deal with two-channel units and functions, which are needed in addition to those for one-channel operation.

IF converter P4LC

The function and purpose of this unit in the channel 2 rack is the same as in one-channel operation (see description in Sections 5.2.1 and 5.2.2). Only the carrier frequency used for obtaining the transmitter and receiver IF's are different (see modulation scheme in Fig. 5.1).

The carrier (local oscillator) frequency of 636 kHz required for modulation by the two-channel transmitter is obtained by dividing the double frequency signal of 1272 kHz from P4LI, which is available at I/P A9/C9.

This frequency is selected automatically for two-channel operation by the signal IF2 SELECT applied to I/P C6.

Similarly, the carrier (local oscillator) frequency of 156 kHz required for demodulation by the two-channel receiver is obtained by dividing the double frequency signal of 312 kHz from P4LI, which is available at I/P's A15/C15. This frequency is selected automatically for two-channel operation by the signal IF2 SELECT ap-plied to I/P C6.

Channel link V9LK

The channel link V9LK is inserted in the channel 2 rack in place of the units P4LF and P4LD and fulfils the following functions:

- connection of the transmitter signal TXIF2 by the coaxial cable V9LG from the IF converter P4LC to the common RF converter P4LF in the channel 1 rack.

- connection of the receiver signal RXIF2 by the coaxial cable V9LG from the common RF receiver con-verter P4LE in the channel 1 rack to the IF converter P4LC.

- connection of the double carrier frequencies 1272 kHz and 312 kHz from the unit P4LI to the IF converter P4LC.

- setting of the switchover signal IF2 SELECT for automatically selecting the carrier frequencies on IF con-verter P4LC needed for two-channel operation.

- connection of the PLUG-OUT1 supervision signal in two-channel operation.


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RF receiver converter P4LE

With the exception of the RF and IF2 receiver filters, the RX RF converter P4LE and the converter P4LD it replaces in the channel 1 rack are identical (see description of P4LD in Section 5.2.2). All the filters on P4LE have a bandpass width of 8 kHz.

IF2 CARRIER synthesizer P4LI

In two-channel operation, the unit P4LI is inserted in the channel 2 rack in place of the synthesizer P4LG.

This unit generates two fixed carrier frequencies for converting the channel 2 signal from 16-20 kHz to 616-620 kHz (transmitter), respectively from 136-140 kHz down to 16-20 kHz (receiver). The 7.68 MHz quartz local oscillator signal is connected as a push-pull signal by two wires from the synthesizer P4LG to I/P's A30 and C30 of P4LI. Following regeneration and division, frequencies of twice those required for the carriers are generated by two PLL circuits. These signals are available at the balanced O/P's A12/C12 and A20/C20 and are connected by the channel link unit V9LK to the IF converter P4LC, where the carriers of 636 kHz and 156 kHz are obtained by a further stage of division.

In the local loop mode (dummy load P3LK inserted), the LOCAL LOOP signal is derived from the DC signal at I/P C5 and transferred for further processing to units P4LA and P4LB via O/P A5. (The RF signal TX-RF coming from hybrid P3LA/B is applied to I/P C5 during normal operation.)

The signals PLUG-OUT1 (none of the basic channel 1 to 4 units or the common hybrid missing) and PLUG-OUT22 (none of the basic units common to channels 1 and 2, respectively channels 2 and 3 missing) are connected to an OR gate via I/P's C8 and C10. The signal at the O/P of the OR gate goes to the pilot and supervision unit P4LA via O/P A8 of P4LI (see Fig. 2.2).

This enables the following cases in multi-channel operation to be detected:

- missing hybrid P3LA: all channels give alarm - missing P4LB or P4LC unit: corresponding channels give alarm - missing P4LD/E/F/G unit in channel 1 or 3: corresponding channels give alarm

and also in channels 2 and 4 - missing channel link V9LK or P4LI in channel 2 or 4: corresponding channels give alarm

5.13 Three and four-channel PLC equipment Types ETL43/44

See block diagrams Channel 1 carrier section, 5HYN589136-CA, Appendix A.2 and Channel 2 carrier section, 5HYN589135-CA, Appendix A.2

ETL can be equipped for three or four-channel operation by adding further racks Type P7LB with the corre-sponding ancillary units.

The AF functions, the conversion to the first IF and the supervision functions are identical in all channels (see description of the carrier frequency section P4LB in Section 5.2 and Sections 5.5 to 5.11).

The arrangement of the functions in the channel 3 rack corresponds to that of channel 1 (see block diagram of the channel 1 carrier frequency section, 5HYN589136-CA).


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The arrangement of the functions in the channel 4 rack corresponds to that of channel 2 (see block diagram of the channel 2 carrier frequency section, 5HYN589135-CA).

By laying channel 2 (4) block diagram 5HYN589135-CA on top of the channel 1 (3) block diagram 5HYN589136-CA, it is easy to see the complete layout for three and four-channel operation.

The modulation scheme for three and four-channel operation is described in Section 5.1.

The equipment racks for three and four-channel operation differ from those for one-channel operation in the following points:

Channel 3:

- Identical units fitted for three-channel operation as for channel 1. The channel 1 RX RF converter P4LD is replaced by the channel 2 RX RF converter P4LE in four-channel operation.


Channel 4:

- The TX RF converter P4LF and the RX RF converter P4LD are replaced by the channel link V9LK.

- The frequency synthesizer P4LG is replaced by the synthesizer P4LI.

- The IF converter P4LC uses the 636 kHz and 156 kHz carriers from P4LI, which are shifted by 4 kHz.



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5.14 Auxiliary supply

See block diagram of the 40 W power supply, 5HYN589138-CA, Appendix A.2

ETL PLC equipment can be connected to the following auxiliary supply sources:

Secure AC supply 110/230V AC +10/-15 % 45 to 65 Hz Station battery 48 V DC Ripple <5 % pp +20/-15 %

In all cases, the auxiliary supply units used provide DC isolation of the PLC equipment from the supply source. The channel racks are supplied by individual DC/DC converters. The power amplifier is DC isolated from the rest of the circuits by transformers with a high I/P and O/P voltage withstand capability.

The supply system comprises 2 units:

- a power supply unit B5LA (48 V DC station battery supply) or B5LC (secure AC supply) installed in equipment rack P7LA

- a DC/DC converter B4LA (single supply) or B4LB (double supply unit) for the supply of and installed in the P7LB channel racks.

The alternative versions of power supply units and DC/DC converters used are listed in Table 2.10.

The power supply unit B5LA/C is connected via the back plane PCB NA, the correspondingly marked Faston connectors on the side plate of the rack and the cubicle cabling to the supply source. The power amplifier P1LA is supplied directly with unstabilised DC via O/P B20/B23. The DC/DC converter B4LA/B in the channel rack P7LB is supplied from the B5LA/C via a second O/P B26/B29, the back plane PCB NA and the connecting cable V9LL.

Each channel rack is normally equipped with its own DC/DC converter B4LA. Where a channel 2 rack only has two AF options O4LA, including E1LA and O4LB/C, it may be supplied in parallel from channel 1's B4LA DC/DC converter. The same applies to supplying channel 4 in parallel from the DC/DC converter in the channel 3 rack. Where five NSK 5 modems are installed in a rack, a B4LB must be fitted in order to supply the load. The stabilised secondary voltages of ±12.8 V and +5 V are connected via diodes and O/P's Z24, D22 and D26 to the back plane auxiliary supply busbars. The busbar voltages are monitored by the pilot and supervision unit P4LA. In the case of the DC/DC converter B4LB (double supply unit), the failure of just one supply module causes a WARNING signal to be sent to the supervision unit.

Each of the power supply units B5LA/C has the following:

- a stand-by signal on the frontplate (green LED) showing that the unit is serviceable

- fail-safe test sockets on the frontplate for checking the unstabilised secondary DC voltage


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- a fuse and a miniature circuit-breaker for overload and short-circuit protection.

48 V DC power supply unit B5LA

The supply unit is designed for supplying the PLC equipment from a 48 V DC battery. The battery circuit may be earthed at the positive pole or at a centre point, or it may be floating. The supply unit comprises essentially a filter circuit and a protection circuit to limit the inrush current. The battery voltage is connected to I/P B5/B8 and after being filtered is fed via O/P B20/B23 to the series regulator of the power amplifier P1LA. The DC/DC converters B4LA/B in the P7LB channel racks are supplied via reverse flow blocking diodes and a second O/P B29/B26. A varistor across the input of the unit limits voltage spikes. The unit is protected against reversal of polarity and by a 6.3 A slow fuse. A circuit for limiting the inrush current only permits the contacts of K1 to close following a delay after switching on. The m.c.b. F2 accessible on the frontplate has a tripping characteristic, which effectively protects the unit against overload. Fail-safe test sockets on the frontplate facilitate measurement of the battery supply voltage and the secondary unstabilised O/P voltage.

110/230 V AC power supply unit B5LC

The supply unit is designed for supplying the PLC equipment from 110 V AC, respectively 230 V AC. The unit comprises essentially a power transformer, a rectifier and a smoothing filter. The AC supply voltage is connected to the I/P terminals B14 (ph) and B17 (N) and thence to the primary of the transformer. The pre-stabilised DC is fed via the smoothing filter and O/P B23/B20 to the series regulator of the power amplifier P1LA. The DC/DC converters in the channel racks are supplied via O/P B26/B29. The primary of the supply unit is protected by a fuse and a varistor to limit voltage spikes. The m.c.b. F2 accessible on the frontplate has a tripping characteristic, which effectively protects the unit against overload. Fail-safe test sockets on the frontplate facilitate measurement of the primary AC supply voltage and the secondary unstabilised DC O/P voltage.

48 V DC/DC converter B4LA

The DC/DC converter provides a DC isolated auxiliary supply for the channel rack P7LB. The unstabilised primary voltage of 40-60 V DC comes from the power supply unit B5LA/C via the connecting cable V9LL to I/P Z28/D30. The stabilised and filtered O/P voltages are connected to the back plane busbars of the rack and to the supervision unit P4LA via O/P's D22, Z24 and D26.

The primary I/P voltage and the O/P currents are monitored internally and LED's on the frontplate give warning should they fall out of tolerance. The LED marked "ON" indicates that the DC/DC converter is oper-ating normally (see Table 2.4). The unit includes the following protective functions:

- inrush current limiter - 3.15 A slow fuse - overload protection (O/P current limiter) - protection against reversal of polarity - overtemperature - overvoltage

Utility Communication Systems Operating modes ETL41/42/43/44

6 - 1 5HYN589126-TA

PART II APPLICATION, PROGRAMMING AND TESTING

6. OPERATING MODES

6.1 Multi-purpose mode (main operating mode)

The ETL series of PLC equipment was designed from the outset for multi-purpose operation. This mode enables the best possible use to be made of the bandwidth available for the communication of speech, data and teleprotection signals. A typical allocation of frequencies in the AF channel can be seen from Fig. 2.1. In conjunction with the AF interfaces described in Sections 2 and 5, the teleprotection device NSD 50 and the data modem NSK 5, an optimum solution can be found for every application. The AF bus in the channel rack P7LB provides great flexibility when it comes to configuring user interfaces (AF options). Any combination of as many as five AF ancillary units can be accommodated in the P7LB. This maximum number reduces to four, respectively three when the ETL is equipped with a teleprotection device NSD 50 (see Appendix A.1).

The AF channel can be used for the following services and applications:

Speech communication:

- 4-wire PAX-PAX operation AF option O4LB - 2/4-wire PAX-PAX operation AF option O4LC - 4-wire remote subscriber AF option O4LD/O4LB - 2-wire remote subscriber AF option O4LD/O4LD

Since all the speech interfaces can be programmed for different bandwidths, the transfer of data via the speech interfaces using dial-up modems is possible (CCITT V.27, V.29, e.g. for telefax).

Data communication:

- signals from external AF modems and VFT channels using telecontrol interface O4LA

- data transmission via the serial interface of an incorporated NSK 5 modem

- selective relaying of data channels using the transit filter E1LA (option on O4LA)

Teleprotection signalling:

- built-in teleprotection device NSD 50:

Smallest version: transmission of 2 independent tripping signals with provision for expansion to 4 tripping signals, of which 2 permissive and 2 direct.

- provision for connecting external teleprotection devices (e.g. NSD 70 or NSD 61) via the boostable inter-face AUX. AF INPUT/OUTPUT on P4LB.

Utility Communication Systems Operating modes ETL41/42/43/44

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Repeater operation:

The interface AUX. AF INPUT/OUTPUT on P4LB is also used for relaying the entire AF band through inter-mediate stations. This can be done either in a broadband range up to 3850 Hz or limited to 3600 Hz with suppression of the pilot signal by means of a plug-in hybrid filter (option). In such cases, the dialling signal is relayed via the signalling interfaces AUX. SIGNALLING.

6.2 Single-purpose mode

ETL equipment is also suitable without any changes for just any one of the multi-purpose services men-tioned above, e.g. for transferring just teleprotection signals.

6.3 Multi-channel mode

The majority of PLC equipment is applied for one and two-channel operation. The use of three or four-channel units on EHV transmission lines can generally be excluded.

To ensure that the quality of the transmission is adequate in view of the SNR and the limited transmission power, it is essential for the scheme to be carefully studied before deciding on a three or a four-channel scheme. Problems may also be encountered in some cases in making a frequency band of 12 or 16 kHz available together with the required gaps in each direction.

Multi-channel operation is basically possible in the following cases:

at power system voltages < 220 kV

when transmitting via insulated ground wires

when transmitting via cables (e.g. in addition to existing ETM12 links via coaxial ground wire cables).

Utility Communication Systems Alternative versions ETL41/42/43/44

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7. ALTERNATIVE VERSIONS

The different versions of ETL equipment vary in the types of units used, the programming and the settings on the units.

The units fitted in the equipment rack P7LA and the basic units in the channel rack P7LB have fixed loca-tions. This also applies to the units of the teleprotection device NSD 50 and the auxiliary supply unit in the channel rack. The AF options, however, can occupy different locations in a rack.

Diagrams showing the locations of the units for:

- one-channel versions - two-channel versions - three and four-channel versions

are to be found in Appendix A.1.

Utility Communication Systems Setting and programming ETL41/42/43/44 alternative versions

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8. SETTING AND PROGRAMMING ALTERNATIVE VERSIONS

The setting, programming and tuning instructions for all the alternative versions and units bearing an influ-ence on frequency are given in supplementary document, which includes the following lower level documents:

- Alternative programming 5HYN589096-TA

- Tuning instructions for the carrier generator P4LG 5HYN589097-TA

Utility Communication Systems System level/equipment settings ETL41/42/43/44

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9. SYSTEM LEVEL, EQUIPMENT SETTINGS

9.1 Basic terms

Absolute power level L [dBm]

The absolute power level L defines by how many dB a signal strength Px is greater or less than the reference power P0 = 1 mW:

Px L = 10 log ------ [dBm] 1 mW

Absolute voltage level Lu [dBu]

The absolute voltage level Lu defines by how many dB a signal voltage Ux is greater or less than the refer-ence voltage U0 = 775 mV:

Ux Lu = 20 log ------- [dBu] 775 mV

Absolute signal level L0 [dBm0]

In order to be able to compare signals in relation to a common base level, they are defined in relation to a system reference point with a relative level of 0 dBr,

Absolute noise level on the speech channel L0p [dBm0p]

This is basically the same as L0, but the index "p" signifies that it concerns a psophometrical (weighted) level, which is generally defined according to CCITT. It is only used in connection with the specification of noise levels on speech channels.

Conversion to another system impedance

If the voltage level is measured at a correctly terminated point of the system and referred to 600 Ohm, the value of Lu is the same as the power level L. The value must be converted as follows for other impedances Z:

600 Ohm Lu [dBu] = L [dBm] - 10 log -------- Z [Ohm]

Example: The power level at the 75 Ohm RF O/P of a PLC equipment is given as 40 dBm. What is the volt-age level Lu?


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600 Ohm Lu = 40 dBm - 10 log -------- = 31 dBu 75 Ohm

Modern power measuring instruments permit the reference impedance to be set and the level referred to 600 Ohm can be directly read from them.

Relative level Lrel [dBr]

The relative level Lrel is used, in order to define the performance of a communications system regardless of channel loading.

The dBr value defines the magnitude of the difference in level with respect to the (virtual) reference point (0dBr).

Previously the two-wire I/P was taken as the reference point in telephony systems, which corresponds to the I/P of the AF hybrid in a PLC system. As with the dBm value, the relative system level (dBr) is equivalent to a power level.

Calculation of the absolute level

Where in a communications system the relative level Lrel and the absolute signal level L0 are known, the absolute level L at specified points can be calculated as follows:

L [dBm] = Lrel [dBr] + L0 [dBm0]

Voltage levels are more suitable for measurement purposes and level adjustment and expressed in voltage levels, the above relationship becomes:

Lu [dBu] = Lrel [dBr] + L0 [dBm0]

The source impedance of the ETL test sockets has been chosen such that when terminated across a high impedance, the voltage level Lu [dBu] has the same value as the power level L [dBm] when terminated across 75 Ohm.


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9.2 Allocating powers to speech and data channels

The channels of a multi-purpose PLC equipment usually transmit different kinds of signals. When designing a PLC system, the noise occurring along the HV transmission line (corona) has to be added to the powers of the useful signals.

In the case of white noise, the power of the noise is proportional to bandwidth.

A 50 Bd VFT channel has a noise bandwidth of about 80 Hz. Compared with a 300 Hz-2400 Hz speech channel, the noise power level on a 50 Bd channel is thus about 14 dB lower. Correspondingly, to maintain the same SNR, the signal level of the 50 Bd channel may be chosen 14 dB lower than the nominal speech level.

Therefore by choosing signal powers proportional to the noise bandwidths, all the channels have the same SNR, i.e. the same reach.

Table 9.1 lists the signal levels [dBm0], their associated weightings and the absolute voltage levels [dBu] as measured at the -10 dBr test sockets TXAF for the speech and VFT channels.

AF signals Signal levels Absolute voltage levels at the test sockets TXAF (-10 dBr)

dBm0 Weighting dBu

Speech test tone 800 Hz 0 1.0 -10 Internal test tone 1000 Hz Speech with safety margin +3 1.41 -7 VFT channels and modems 50 Bd -14 0.2 -24 100 Bd -11 0.28 -21 200 Bd -8 0.4 -18 600 Bd -3 0.71 -13 1200 Bd, V.23 0 1 -10 1200 Bd + speech -3 0.71 -13 2400 Bd 0 1.0 -10 Max. permissible load with +10.8 3.48 +0.8 speech plus superimposed channels Pilot tone -6 0.5 -16

Table 9.1 Allocation of powers to speech and VFT channels


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9.3 Determining the transmission levels for ETL41/42

The transmitter level setting resulting from the allocation of channel powers is determined by simply adding the voltage weightings of the individual channels given in Table 9.1. This value is then set on the program-ming switch S1 on the RF converter P4LF.

The signal levels required for calculation, setting and testing are defined below.

POWER T [dBm]: test tone level at the RF O/P across the dummy load. T(RF) [dBu]: test tone level at the test sockets RF LINE on P3LA. 0 dBu corresponds to 10 W S(W1): sum of the voltage weighting of all the channel 1 signals including the pilot S(W2): sum of the voltage weighting of all the channel 2 signals including the pilot S(W) = S(W1) + S(W2) Permissible allocation to the channels for one and two-channel operation ETL41: 2.4 < S(W) µ 3.5 ETL42: 3.0 < S(W) µ 7.0 S: setting on P4LF

Calculation of the transmitter level

1) Sum of the channel 1 voltage weightings: S(W1)

S(W1) = [n0*1.41 + n1*0.2 + n2*0.28 + n3*0.4 + n4*0.71 + n5*1.0(0.71) + n6*1.0 + 0.5]

where:

n0 n0 = 1, for speech, otherwise n = 0 n1 No. of 50 Baud data channels n2 No. of 100 Baud data channels n3 No. of 200 Baud data channels n4 No. of 600 Baud data channels n5 No. of 1200 Baud data channels,1200 Bd V.23: weighting 1.0 1200 Bd above speech channel: weighting 0.71 n6 = 1, for a 2400 Bd data channel, otherwise 0

Channel 2: The calculation of S(W2) is the same as for S(W1), but with the channel 2 signal allocation.


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2) Setting on P4LF: S S = S(W) - 0.5 3) Transmitter test tone level at the RF O/P: POWER T POWER T = LPEP - 20*log S(W) (dBm) where: LPEP(dBm): transmitter power available +45 dBm with 40 W equipment Note: The RF test tone level POWER T applies to channel 1 and channel 2. 4) Test tone level at the test sockets on P3LA: T(RF) T(RF) = POWER T - 40 dB [dBu]

The levels POWER T and T (RF) do not have to be calculated, since they can be read against the calculated S(W) value from Table 9.2.

Example ETL 41

Allocation: speech + 600 Bd

1) Sum of channel 1 voltage weightings: S(W1) S(W) = S(W1) = [1.41 + 0.71 + 0.5] = 2.62 which is rounded to S(W) = 2.6

2) Setting on P4LF: S S = S(W) - 0.5 S = 2.6 - 0.5 = 2.1 Setting on P4LF: S = 2.1


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3) Transmitter test tone level at the RF O/P: POWER T POWER T = LPEP - 20*log S(W) [dBm] POWER T = 45 dBm - 20*log [2.6] = 36.7 dBm

4) Test tone level at the test sockets on P3LA: T(RF) T(RF) = POWER T - 40 dB [dBu] T(RF) = 36.7 dBm - 40 dB = -3.3 dBu

Example ETL 41

Allocation: NSK 5 2400 Bd

1) Sum of channel 1 voltage weightings S(W) = S(W1) = 1 + 0.5 = 1.5 Since the available setting range is 2.4 < S(W) < 3.5, S(W) = 2.4 has to be chosen.

2) Setting on P4LF:S S = 2.4 - 0.5 = 1.9

3) Transmitter test tone level at the RF O/P Power T = 45 dBm - 20 log 2.4 = 37.4 dBm

4) Test tone level at the test sockets on P3LA T(RF) = 37.4 dBm - 40 dB = -2.6 dBu


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Example ETL 42

Channel 1 allocation: speech + VFT 600 Baud Channel 2 allocation: VFT channel 1200 Baud, V.23

1) Sum of channel 1 and channel 2 voltage weightings: S(W1) = [1.41 + 0.71 + 0.5] = 2.62 S(W2) = [1.0 + 0.5] = 1.50 S(W) 4.12 which is rounded to S(W) = 4.1

2) Setting on P4LF: S S = 4.1 - 0.5 = 3.6

3) Transmitter test tone level at the RF O/P: POWER T POWER T = 45 dBm - 20*log 4.1 = 32.7 dBm

4) Test tone level at the test sockets on P3LA: T(RF) T(RF) = 32.7 dBm - 40 dB = -7.3 dBu


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9.4 Determining the transmission levels for ETL43/44

The procedure for determining the channel 3 and 4 level settings is basically the same as described in Sec-tion 9.3. The following, however, must be observed to ensure that the same test tone level results, even if the allocations for channels 1 and 2 (1 + 2) and for channels 3 and 4 (3 + 4) are different.

Definitions:

S(W1): sum of all channel 1 voltage weightings including the pilot




S(W12)= S(W1) + S(W2)

S(W34)= S(W3) + S(W4)

S(Wmax.): the greater of the two values S(W12) and S(W34)

S: setting on P4LF, same for channels (1+2) and channels (3+4)

1.26[S(W12) + S(W34)] The following rule applies: When ------------------ · S(Wmax) 2

then: S = [S(W12) + S(W34)]/2 - 0.5

otherwise: S = S(Wmax)/1.26 - 0.5

This means that when the mean of the voltage weightings is not more than a factor 1.26 less than the greater of the two values, the transmitter power is set to the mean value.

If the mean is less than this value, the greater value reduced by a factor of 1.26 is taken as the setting.

With this compromise setting, the amplifier on the transmitter RF converter P4LF of the two more heavily loaded channels is driven a maximum of 2 dB more than the others.

S(W) = 2 S + 1 The permissible channel allocation for three and four-channel operation is thus ETL43: 3.5 < S(W) ≤ 10.5 ETL44: 4.0 < S(W) ≤ 14.0


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Example ETL44

Channel 1 allocation: speech + pilot S(W1) = 1.9 Channel 2 allocation: 1200 Bd, V.23 + pilot S(W2) = 1.5 S(W12) = 3.4

Channel 3 allocation: 3*600 Bd + pilot S(W3) = 2.6 Channel 4 allocation: 4*200 Bd + pilot S(W4) = 2.1 S(W34) = 4.7

1.26[S(W12) + S(W34)] ------------------ = 5.1 > S(Wmax) = 4.7 2

(3.4 + 4.7) i.e.: S = --------- - 0.5 = 3.55 (3.6) 2

S(W) = 2S + 1 = 2 * 3.6 + 1 = 8.2 Power T = +45 dBm - 20 log 8.2 = 26.7 dBm T(RF) = 27 dBm - 40 dB = -13.3 dBu

Example ETL 43

Channel 1 allocation: speech + pilot S(W1) = 1.9 Channel 2 allocation: 1200 Bd, V.23 + pilot S(W2) = 1.5 S(W12) = 3.4 Channel 2 allocation: 4*200 Bd + pilot S(W3) = 2.1 S(W34) = 2.1

1.26[S(W12) + S(W34)] ------------------ = 3.47 > S(Wmax) = 4.7 2

(3.4 + 2.1) i.e.: S = --------- - 0.5 = 2.25 (2.3) 2

S(W) = 2*2.3 + 1 = 5.6 Power T = +45 dBm - 20 log 5.6 = 30.0 dBm T(RF) = 30.0 dBm - 40 dB = -10.0 dBu


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Channel loading ETL 41, 42, 43, 44

Settings on P4LF S(W) S(ETL41) S(ETL42) S(ETL43) S(ETL44) Power T T(RF)

P4LF Ch1 P4LF Ch1 P4LF Ch1+3 P4LF Ch1+3 [dBm] [dBu] 2.4 1.9 37.4 -2.6 2.5 2.0 37.0 -3.0 2.6 2.1 36.7 -3.3 2.7 2.2 36.4 -3.6 2.8 2.3 36.1 -3.9 2.9 2.4 35.8 -4.2 3.0 2.5 2.5 35.5 -4.5 3.1 2.6 2.6 35.2 -4.8 3.2 2.7 2.7 34.9 -5.1 3.3 2.8 2.8 34.6 -5.4 3.4 2.9 2.9 34.4 -5.6 3.5 3.0 3.0 1.3 34.1 -5.9 3.6 3.1 3.1 1.3 33.9 -6.1 3.7 3.2 3.2 1.4 33.6 -6.4 3.8 3.3 3.3 1.4 33.4 -6.6 3.9 3.4 3.4 1.5 33.2 -6.8 4.0 3.5 3.5 1.5 1.5 33.0 -7.0 4.1 3.6 3.6 1.6 1.6 32.7 -7.3 4.2 3.7 3.7 1.6 1.6 32.5 -7.5 4.3 3.8 3.8 1.7 1.7 32.3 -7.7 4.4 3.9 3.9 1.7 1.7 32.1 -7.9 4.5 4.0 4.0 1.8 1.8 31.9 -8.1 4.6 4.1 4.1 1.8 1.8 31.7 -8.3 4.7 4.2 4.2 1.9 1.9 31.6 -8.4 4.8 4.3 4.3 1.9 1.9 31.4 -8.6 4.9 4.4 4.4 2.0 2.0 31.2 -8.8 5.0 4.5 4.5 2.0 2.0 31.0 -9.0 5.1 4.6 4.6 2.1 2.1 30.8 -9.2 5.2 4.7 4.7 2.1 2.1 30.7 -9.3 5.3 4.8 4.8 2.2 2.2 30.5 -9.5 5.4 4.9 4.9 2.2 2.2 30.4 -9.6 5.5 5.0 5.0 2.3 2.3 30.2 -9.8 5.6 5.1 5.1 2.3 2.3 30.0 -10.0 5.7 5.2 5.2 2.4 2.4 29.9 -10.1 5.8 5.3 5.3 2.4 2.4 29.7 -10.3 5.9 5.4 5.4 2.5 2.5 29.6 -10.4 6.0 5.5 5.5 2.5 2.5 29.4 -10.6 6.1 5.6 5.6 2.6 2.6 29.3 -10.7 6.2 5.7 5.7 2.6 2.6 29.2 -10.8 6.3 5.8 5.8 2.7 2.7 29.0 -11.0 6.4 5.9 5.9 2.7 2.7 28.9 -11.1 6.5 6.0 6.0 2.8 2.8 28.7 -11.3 6.6 6.1 6.1 2.8 2.8 28.6 -11.4 6.7 6.2 6.2 2.9 2.9 28.5 -11.5 6.8 6.3 6.3 2.9 2.9 28.3 -11.7 6.9 6.4 6.4 3.0 3.0 28.2 -11.8 7.0 6.5 6.5 3.0 3.0 28.1 -11.9 7.1 6.6 6.6 3.0 3.0 28.0 -12.0 7.2 6.7 6.7 3.1 3.1 27.9 -12.1


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S(W) S(ETL41) S(ETL42) S(ETL43) S(ETL44) Power T T(RF) P4LF Ch1 P4LF Ch1 P4LF Ch1+3 P4LF Ch1+3 [dBm] [dBu]

7.3 6.8 6.8 3.1 3.1 27.7 -12.3 7.4 6.9 6.9 3.2 3.2 27.6 -12.4 7.5 7.0 7.0 3.2 3.2 27.5 -12.5 7.6 7.1 7.1 3.3 3.3 27.4 -12.6 7.7 7.2 7.2 3.3 3.3 27.3 -12.7 7.8 7.3 7.3 3.4 3.4 27.2 -12.8 7.9 7.4 7.4 3.4 3.4 27.0 -13.0 8.0 7.5 7.5 3.5 3.5 26.9 -13.1 8.1 7.6 7.6 3.5 3.5 26.8 -13.2 8.2 7.7 7.7 3.6 3.6 26.7 -13.3 8.3 7.8 7.8 3.6 3.6 26.6 -13.4 8.4 7.9 7.9 3.7 3.7 26.5 -13.5 8.5 8.0 8.0 3.7 3.7 26.4 -13.6 8.6 8.1 8.1 3.8 3.8 26.3 -13.7 8.7 3.8 3.8 26.2 -13.8 8.8 3.9 3.9 26.1 -13.9 8.9 3.9 3.9 26.0 -14.0 9.0 4.0 4.0 25.9 -14.1 9.1 4.0 4.0 25.8 -14.2 9.2 4.1 4.1 25.7 -14.3 9.3 4.1 4.1 25.6 -14.4 9.4 4.2 4.2 25.5 -14.5 9.5 4.2 4.2 25.4 -14.6 9.6 4.3 4.3 25.4 -14.6 9.7 4.3 4.3 25.3 -14.7 9.8 4.4 4.4 25.2 -14.8 9.9 4.4 4.4 25.1 -14.9 10.0 4.5 4.5 25.0 -15.0 10.1 4.5 4.5 24.9 -15.1 10.2 4.6 4.6 24.8 -15.2 10.3 4.6 4.6 24.7 -15.3 10.4 4.7 4.7 24.7 -15.3 10.5 4.7 4.7 24.6 -15.4 10.6 4.8 4.8 24.5 -15.5 10.7 4.8 4.8 24.4 -15.6 10.8 4.9 4.9 24.3 -15.7 10.9 4.9 4.9 24.3 -15.7 11.0 5.0 5.0 24.2 -15.8 11.1 5.0 5.0 24.1 -15.9 11.2 5.1 5.1 24.0 -16.0 11.3 5.1 5.1 23.9 -16.1 11.4 5.2 5.2 23.9 -16.1 11.5 5.2 5.2 23.8 -16.2 11.6 5.3 5.3 23.7 -16.3 11.7 5.3 5.3 23.6 -16.4 11.8 5.4 5.4 23.6 -16.4 11.9 5.4 5.4 23.5 -16.5 12.0 5.5 5.5 23.4 -16.6 12.1 5.5 5.5 23.3 -16.7 12.2 5.6 5.6 23.3 -16.7 12.3 5.6 5.6 23.2 -16.8


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S(W) S(ETL41) S(ETL42) S(ETL43) S(ETL44) Power T T(RF) P4LF Ch1 P4LF Ch1 P4LF Ch1+3 P4LF Ch1+3 [dBm] [dBu]

12.4 5.7 5.7 23.1 -16.9 12.5 5.7 5.7 23.1 -16.9 12.6 5.8 5.8 23.0 -17.0 12.7 5.8 5.8 22.9 -17.1 12.8 5.9 5.9 22.9 -17.1 12.9 5.9 5.9 22.8 -17.2 13.0 6.0 6.0 22.7 -17.3 13.1 6.0 6.0 22.7 -17.3 13.2 6.1 6.1 22.6 -17.4 13.3 6.1 6.1 22.5 -17.5 13.4 6.2 6.2 22.5 -17.5 13.5 6.2 6.2 22.4 -17.6 13.6 6.3 6.3 22.3 -17.7 13.7 6.3 6.3 22.3 -17.7 13.8 6.4 6.4 22.2 -17.8 13.9 6.4 6.4 22.1 -17.9 14.0 6.5 6.5 22.1 -17.9 14.1 6.5 6.5 22.0 -18.0 14.2 6.6 6.6 22.0 -18.0 14.3 6.6 6.6 21.9 -18.1 14.4 6.7 6.7 21.8 -18.2 14.5 6.7 6.7 21.8 -18.2 14.6 6.8 6.8 21.7 -18.3 14.7 6.8 6.8 21.7 -18.3 14.8 6.9 6.9 21.6 -18.4 14.9 6.9 6.9 21.5 -18.5 15.0 7.0 7.0 21.5 -18.5 15.1 7.0 7.0 21.4 -18.6 15.2 7.1 7.1 21.4 -18.6 15.3 7.1 7.1 21.3 -18.7 15.4 7.2 7.2 21.2 -18.8 15.5 7.2 7.2 21.2 -18.8 15.6 7.3 7.3 21.1 -18.9 15.7 7.3 7.3 21.1 -18.9 15.8 7.4 7.4 21.0 -19.0 15.9 7.4 7.4 21.0 -19.0 16.0 7.5 7.5 20.9 -19.1 16.1 7.5 7.5 20.9 -19.1 16.2 7.6 7.6 20.8 -19.2 16.3 7.6 7.6 20.8 -19.2 16.4 7.7 7.7 20.7 -19.3 16.5 7.7 7.7 20.7 -19.3 16.6 7.8 7.8 20.6 -19.4 16.7 7.8 7.8 20.5 -19.5 16.8 7.9 7.9 20.5 -19.5 16.9 7.9 7.9 20.4 -19.6 17.0 8.0 8.0 20.4 -19.6 17.1 8.0 8.0 20.3 -19.7 17.2 8.1 8.1 20.3 -19.7

Table 9.2 Channel loading, transmitter level and settings on P4LF


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9.5 Reduced O/P power

In cases where the O/P power has to be reduced, this can be achieved by programming the setting for S on P4LF.

Definitions:

S (40 Watt): setting on P4LF for PEP = 40 Watt

S (X Watt): setting on P4LF for a reducing power to PEP = X Watt

S (X Watt) = [S (40 Watt) + 0.5] * √(40/X - 0.5)

S (X Watt) ≤ 8.1 (S = 8.1 is the maximum possible setting on P4LF)

Examples

ETL41: speech + 600 Bd

S(W) = 1.41 + 0.71 + 0.5 = 2.6

S(40 Watt) = 2.6 - 0.5 = 2.1

Power T = +45 dBm - 20 log 2.6 = +36.7 dBm

T(RF) = +36.7 dBm - 40 dB = -3.3 dBu

Reduction to 20 Watt:

S (20 Watt)= (2.1 + 0.5) * 1.41 - 0.5 = 3.2

S(W) = 3.2 + 0.5 = 3.7

Power T = +45 dBm - 20 log 3.7 = 33.6 dBm

T(RX) = 33.6 dBm - 40 dB = -6.4 dBu


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Reduction to 10 Watt:

S (10 Watt)= (2.1 + 0.5) * 2 - 0.5 = 4.7

S(W) = 4.7 + 0.5 = 5.2

Power T = +45 dBm - 20 log 5.2 = 30.7 dBm

T(RX) = 30.7 dBm - 40 dB = -9.3 dBu

The modified value of S for the reduced power can be found simply from Table 9.2.

- Read the value for the power T in column 6 for normal operation PEP = 40 Watt

- Reduction of the power T by 3 dB for PEP = 20 Watt by 6 dB for PEP = 10 Watt

- Read the modified value of S in column 2 or column 3. (Reducing power only makes sense for ETL41/42.)

Remark: The setting ranges marked may only be used for reductions of power and not for channel loading (see Sections 9.3 and 9.4).

9.6 Signal boosting for teleprotection channels

Boosting NSD 50

Boosting refers to increasing the strength of tripping signals in relation to the quiescent state (i.e. the un-boosted test tone level is 0 dBm0). In the case of PLC, this involves interrupting the transmission of speech and usually also of the modem signals in the "superaudio" channel above the speech signals, so that the full ETL transmitter power is available for transmitting the teleprotection signals. This achieves the maximum SNR at the receiver. The ratio between the power of the boosted teleprotection signal and the power of the test tone signal is defined as the boost ratio BR and is normally expressed in decibels.

The achievable boost ratio depends on which PLC signals may be interrupted during the transmission of the teleprotection signals. This, however, depends on PLC channel allocation and for this reason the boost ratio is not set on the NSD 50, but on the PLC equipment.

The NSD 50 teleprotection signal is therefore boosted on the AF converter P4LB.

The boost ratio can be set on DIL switches to one of the following values: 0 dB, 5 dB, 7 dB, 9 dB.

Other values are possible in exceptional circumstances with the aid of ENFX resistors.


9 - 15 5HYN589126-TA

NSD 50 Boost ratio Test tone Teleprotection Voltage weighting set on P4LB level signal level

0 dB 0 dBm0 0 dBm0 + 0 dB 1.00 5 dB 0 dBm0 0 dBm0 + 5 dB 1.78 7 dB 0 dBm0 0 dBm0 + 7 dB 2.24 9 dB 0 dBm0 0 dBm0 + 9 dB 2.82

The boost ratio is calculated using the following equations:

a) PLC with speech:

HTV [dB] = 20*log 1.9 + n1*0.2 + n2*0.28 + n3*0.4 + n4*0.71 + n5*1.0(0.71)

b) PLC without speech:

HTV [dB] = 20*log 1.5 + n1*0.2 + n2*0.28 + n3*0.4 + n4*0.71 + n5*1.0(0.71)

where:

HTV (dB): boost ratio in decibels log: logarithm to the base 10 n1: No. of interruptible 50 Baud data channels n2: No. of interruptible 100 Baud data channels n3: No. of interruptible 200 Baud data channels n4: No. of interruptible 600 Baud data channels n5: No. of interruptible 1200 Baud data channels 1200 Bd V.23: weighting 1.0 1200 Bd above speech: weighting 0.71

The next lower value must be set on the PLC equipment.

Example:

ETL with speech, 2 x 100 Baud and 1 x 200 Baud data HTV (dB) = 20*log 1.9 + 2*0.28 + 1*0.4 = 20*log 2.86 = 9.13 dB Thus the boost setting on P4LB has to be 9 dB.


9 - 16 5HYN589126-TA

External teleprotection device

External teleprotection devices are connected to the interfaces AUX. AF INPUT/OUTPUT on P4LB. The boost instruction is applied to the I/P AUX.BOOST.

NSD 70

The NSD 70 transmission level, i.e. the pilot, is -6 dBm0 for all channels. The boost ratio is also dependent on which channels may be interrupted. The level of boost can be set using DIL switches on P4LB to one of the following values: 0 dB, 5 dB, 7 dB, 9 dB. In all cases the actual setting is the next value down from the one calculated.

The boost ratio is calculated using the following equations:

a) PLC with speech:

HTV [dB] = 20*log 1.9 + n1*0.2 + n2*0.28 + n3*0.4 + n4*0.71 + n5*1.0(0.71) + 6 dB

b) PLC without speech:

HTV [dB] = 20*log 0.5 + n1*0.2 + n2*0.28 + n3*0.4 + n4*0.71 + n5*1.0(0.71) + 6 dB

To prevent overmodulation in the event that tripping signals are generated simultaneously by an NSD 50 and an external teleprotection equipment, the boost logic on P4LB resets the boost signal coming from the external unit to 0 dB.

NSD 61:

The standard NSD 61 scheme operates with its own pilot signal.

Teleprotection and pilot signals have the same levels: -6 dBm0 for 400 Bd and 600 Bd channels.

Since boosting of the teleprotection signal by 6 dB takes place in the NSD 61, this function is not required in the ETL.

Utility Communication Systems Installation ETL41/42/43/44

10 - 1 5HYN589126-TA

PART III INSTALLATION, COMMISSIONING, OPERATION AND MAINTENANCE

10. INSTALLATION

The installation of the equipment can only be successfully accomplished, if it is properly planned before-hand. Planning should not only take the present situation into account, future system expansion must also be included.

10.1 Instructions and recommendations

ESD PROTECTION The modules in this equipment contain CMOS devices, which can be damaged by electrostatic discharges. Appropriate measures must be taken before unpacking modules or withdrawing them from equipment racks. Essential precautions to prevent ESD damage when handling or working on modules are grounding straps for technical personnel and the provision of anti-static work benches. Modules may only be shipped either in their original packing or installed in equipment racks.

10.2 Mechanical inspection

The equipment should be checked for mechanical damage immediately upon receipt. Where damage is as-certained, the last carrier must be notified in writing as quickly as possible. For further assistance in such matters, please consult your local ABB company or agent. The equipment must be switched off during installation. Where the external connections have already been made, all isolating terminals must be open.

10.3 Equipment room

The room where the equipment is installed should be relatively free of dust. Cement floors and walls should be sealed with a suitable paint. Wherever possible, the floor should have a semi-conducting plastic coating.

The room should be well ventilated. Temperature and humidity must be in the range +10 to +45 C°, re-spectively 30 to 70 %. Lead/acid batteries must not be in the same room.


10 - 2 5HYN589126-TA

10.4 Erecting the cubicle

The equipment is normally supplied in the Type E35C ABB cubicle. This cubicle is fitted with a hinged frame for mounting the equipment racks and can be erected in different ways:

- directly against a wall - back-to-back - side-by-side - free-standing

A space of 2 to 3 cm should be left between cubicles mounted side-by-side, to permit a cubicle to be re-moved from the row without difficulty. Sufficient room must be left in front of cubicles to enable the hinged frame to be opened without striking a wall or other obstacles. There should also be sufficient room to give easy access for maintenance and setting up test instruments and equipment.

To allow the hinged frame to be fully opened without hindrance, avoid locating a cubicle in a corner.

Cubicles not equipped with hinged frames must be accessible from the front and from the rear. Cubicles normally stand on a base, which facilitates cleaning the floor and the connection of cables.

CAUTION!

Cubicles, which are not secured to the floor, tip forwards when the hinged frame is opened.

10.5 External connections

Cable access is normally from a cable duct beneath the cubicle.

Connections:

BNC coaxial connectors are provided on the rear of the power amplifier rack P7LA for RF signals (see Ap-pendix A.4).

The auxiliary supply connections are at the top of the left-hand side plate of the power amplifier rack P7LA (see Appendix A.4):

+ positive battery pole

- negative battery pole

ph phase conductor of an AC supply

N neutral conductor of an AC supply

PE earth connection


10 - 3 5HYN589126-TA

The terminal designations for connecting signal cables are to be found in the block diagrams in Appendix A.2. The arrangement and designations of connecting cables are given in Appendix A.4.

Utility Communication Systems Commissioning ETL41/42/43/44

11-1 5HYN589126-TA

11. COMMISSIONING

11.1 Checking the line of communication

It is essential that the behaviour and characteristics of the line of communication between the sets of PLC terminal equipment be checked prior to finally commissioning. This is necessary to confirm the design crite-ria used for engineering the system, respectively if the criteria were inaccurate, to take the appropriate cor-rective action.

The line of communication comprises:

a) the coaxial cable linking the PLC equipment with coupling unit

b) the coupling unit between the remote end of the coaxial cable and the LV side of the coupling capacitor. The coupling unit includes the main coupling filter and protective devices.

c) the line traps in the power line between the junction of the coupling capacitor with the power line and the substation

d) the HV power line itself as propagation medium

11.1.1 Return loss

The return loss is a measure of the quality of impedance matching between the PLC transmitter and the load (I/P impedance of the coaxial cable).

It is defined by the following equation:

Z0 + Z Ar = 20 log ------- Z0 - Z

Z0 rated impedance Z actual I/P impedance

A low value signifies a poor match, which results in a reduced transfer of power from the PLC transmitter onto the transmission line. The main disadvantage, however, is the intermodulation phenomena and associated cross-talk it causes.

The level of return loss should be measured in the equipment room at the coaxial cable I/P. The instruments used and the test set-up can be seen from Figures 11.1 and 11.2. A typical return loss characteristic is shown in Fig. 11.3. In the case of short lines (line attenuation < 15 dB), the remote end must be terminated at rated impedance.


11 - 2 5HYN589126-TA

The measurement of the return loss over the total bandwidth of the coupling filter and the PLC blocking fil-ters is recommended. Wherever possible, the measurements should be carried out twice under the following conditions:

- HV transmission line grounded behind the blocking filter - HV transmission line open behind the blocking filter

If the minimum return loss is in the range 6 to 12 dB, the value of the I/P impedance should also be mea-sured. In cases where the magnitude of the system impedance is too low or too high, an improvement can be achieved by changing the rated impedance of the RF hybrid P3LA (jumper positions 75 or 125 Ohm). Where this is not possible, the O/P power must be reduced in accordance with the following relationship to avoid non-linear distortion:

A(dB)=1/4 [12- Armin]

Minimum values of return loss < 6 dB indicate either a defective coupling or PLC blocking filter, or an inac-ceptable property of the transmission line.

In such instances, the coupling equipment at both ends of the line must be checked using a dummy load as follows:

- Carefully ground the LV end of the coupling capacitor.

- Interrupt the connection between the coupling filter and the coupling capacitor and terminate with a dummy load as shown in Fig. 11.5 or 11.6.

- Measure the return loss of the coupling filter within the rated frequency band.

The instruments and test set-up are shown in Fig. 11.1 and a typical return loss characteristic for a bandpass coupling filter in Fig. 11.4.

Appreciable discrepancies between the measured results and the nominal characteristic point to defective components and the filters must be checked individually.


11-3 5HYN589126-TA

Fig. 11.1 Instruments and test circuit for measuring return

loss

Fig. 11.2 Test circuit for measuring return loss under practical conditions with the transmission line as load


11 - 4 5HYN589126-TA

Fig. 11.3 Typical return loss characteristic under practical conditions with the transmission line as load

Fig. 11.4 Typical return loss characteristic at rated load


11-5 5HYN589126-TA

Fig. 11.5 Test circuit using a dummy load for measuring return loss in the case of single-phase coupling

Fig. 11.6 Test circuit using a dummy load for measuring return loss in the case of phase-to-phase coupling


11 - 6 5HYN589126-TA

11.1.2 Line attenuation

The line attenuation should also be measured over the whole frequency range of the coupling filter and of the line traps. If possible these measurements should be carried out with the transmission line grounded behind the line traps. The test circuit is shown in Figures 11.7 and 11.8.

Unexpectedly high attenuation or fluctuations of attenuation of several dB's within just a few kHz would indi-cate a defective line trap or extremely unusual characteristics of the line itself. It is essential that the cause be found and corrected before the PLC equipment is finally commissioned.

Fig. 11.7 Test circuit for measuring line attenuation in the case of single-phase coupling


11-7 5HYN589126-TA

Fig. 11.8 Test circuit for measuring line attenuation in the case of phase-to-phase coupling

11.2 Commissioning the ETL41/42

Commissioning of the PLC equipment can commence once the measurements of the line of transmission have produced satisfactory results. The following items should be checked before switching on the auxiliary supply. Any discrepancies and anomalies must be rectified without delay.

11.2.1 Preliminary tests and checks

a) Check that the cubicle is earthed in accordance with regulations.

b) Check the polarity of the auxiliary supply connections.

c) Check that the external connections go to the correct terminals in the cubicle according to the specific drawings for the plant.

d) Check that all the internal cables are fitted and correctly inserted.


11 - 8 5HYN589126-TA

e) Check that all the units according to the specific layout diagram for the plant are fitted and in the correct locations.

f) Check that all programming and settings in the units and on the back plane PCB's are in accordance with the specific setting tables for the plant.

11.2.2 Tests according to the commissioning instructions

The equipment was carefully tested and calibrated according to 5HYN600485 prior to delivery and therefore all the internal signal levels will already be at their correct values. Thus only those settings need to be carried out, which are influenced by the practical operating conditions on site, i.e.:

- correction of the transmitter level according to 11.1.1, if necessary

- setting the gain control on the receiver potentiometer on P3LA to its rated operating point (reading 26 ±1 on P4LA)

- frequency distortion equalization on P4LB, if necessary

Basic equipment:

Electronica level oscillator (200Hz-620kHz) Type ET71A Electronica selective level meter (50Hz-620kHz) Type ET71V Scientific dual channel oscilloscope 25MHz HM203 DMM multimeter Fluke 75 Series II frequency counter Philips 120MHz PM6669 AC millivoltmeter Hewlett Packard 3400B

Options:

dummy load P3LK PCB extender 6U/220


11-9 5HYN589126-TA

11.2.3 Local loop test and dummy load P3LK

The dummy load is an important aid for commissioning and fault-finding. By inserting the dummy load P3LK in place of the RF hybrid P3LA, the transmitter no longer operates into the coaxial cable going to the trans-mission line, but into its rated load. This local loop facilitates complete testing of the transmitter and receiver. The act of inserting the unit automatically switches the equipment to the LOOP CONTROL mode. In the loop control mode, transmitter and receiver converters supply the correct RF carriers to the dummy load's frequency converters and the transmitter signal is attenuated and switched to the receiver frequency band.

The AGC function can be tested using the pushbuttons S2 and S3. The unit can be set to 1/2 or 3/4-channel operation to suit the different impedances of the TX filter. As with the RF hybrid, the dummy load processes and signals any TX alarms.

11.2.4 Remote loop test under operational conditions

This is one of the most valuable commissioning and fault-finding aids on site. It enables the AF fre-quency/amplitude characteristic of a PLC channel to be measured and the distortion equalizer in the re-ceiver to be adjusted from one end of the line.

In the remote loop mode, an AF test signal injected at the local PLC equipment is detected by a PLL circuit (tracking filter) in the receiver of the remote equipment and looped to its transmitter at the correct level to be returned to the local equipment. The REMOTE LOOP TEST is initiated, held and started by a microprocessor on P4LA. The procedure for the REMOTE LOOP TEST is described in Section 5.5.2 and in the commissioning instructions 5HYN589145-TA (in the supplementary document 5HYN589144-TA).

11.2.5 Equalizing channel distortion

Equalizing AF channel distortion on ETL equipment is greatly simplified by the remote loop test (see Section 11.2.4). The measurement of the frequency/amplitude characteristic and adjustment of the distor-tion equalizer in the receiver can be accomplished from one end of the line.

The adjustment for frequency/amplitude characteristic equalization is located on the AF converter P4LB at the first IF level IF1 (16-20 kHz). Fluctuations of ±6 dB with respect to the reference level at 800 Hz can be compensated in a frequency band of 300 Hz to 3600 Hz.

The equalizer on the AF converter P4LB can be switched in and out of circuit by a plug-in jumper on the frontplate. Its characteristic is set using the DIL switches S2 and S3 to appropriately compensate the mea-sured frequency/amplitude characteristic. Either a bandpass or a band stop characteristic can be selected with the aid of jumpers RA, RB, RC and RD. The procedure for setting the equalizer is explained in 5HYN589146-TA "Instructions for setting the frequency/amplitude characteristic equalizer P4LB".


11 - 10 5HYN589126-TA

11.3 Programming and tuning the RF channel

Should a change of frequency become necessary, because of PLC system expansion or changed operating conditions, it can be carried out quite simply on site. A change of frequency requires resetting or tuning of :

- synthesizer P4LG

- TX RF filter E5LA/B

- RX RF filter P4LD/E

Utility Communication Systems Operation ETL41/42/43/44

12-1 5HYN589126-TA

12. OPERATION

The operating status of the equipment can be ascertained from the LED signals on the frontplate of the pilot and supervision unit P4LA.

In normal fault-free operation, only the green stand-by LED's on the auxiliary supply units and the LED marked SUP on P4LA are lit. The remaining AGC range can be read from the seven-segment LED.

Any alarm situations are signalled by corresponding red LED's. The double LED can be changed to showing a fault code in the event of an alarm by briefly pressing the test tone button. Further information on the possible cause of the difficulty can then be obtained under the fault code from Table 2.8.

Utility Communication Systems Maintenance ETL41/42/43/44

13 - 1 5HYN589126-TA

13. MAINTENANCE

All the modules are subjected to a burn-in test following manufacture and before comprehensive final func-tional testing. The complete PLC equipment is then calibrated and tested as a unit before leaving the works.

The most important functions, which are critical for the operating characteristics of the equipment, are per-formed digitally by the digital signal processor (DSP) on the pilot and supervision unit P4LA.

The stability of these settings and thus also of the equipment as a whole is assured over a long period of time.

Nevertheless, testing at periodic intervals is recommended. The frequency of testing depends very much on the operating conditions in the particular installation, but should not be less than once every two years.

The following periodic measurements are recommended:

- stabilised DC auxiliary supply voltages - selected AF and RF levels (e.g. pilot) - AGC operating level (gives indication of fluctuating line attenuation)

It is important that the reasons for readings, which diverge widely from values recorded during commis-sioning, be found, even if this means checking the entire equipment.

Checking and testing should only be carried out by correspondingly qualified and authorised personnel us-ing suitable instruments. Incorrect settings can impair the proper operation of the equipment.


A1 - 1 5HYN589126-TA

PART IV APPENDICES

A.1 ALTERNATIVE VERSIONS

ETL41 Front view Rear view Module arrangement Mechanical dimensions 5HYN589127-AA Cabinet layout 5HYN589246-AA




Dimensioned drawing of cubicle Type E35C 5HYN589131-AA

ETL41/42/43/44 List of modules


A1 - 4 5HYN589126-TA


A1 - 9 5HYN589126-TA


A1 - 14 5HYN589126-TA


A1 - 19 5HYN589126-TA

Utility Communication Systems Block diagrams ETL41/42/43/44

A2 - 1 5HYN589126-TA

A.2 BLOCK DIAGRAMS

ETL41/42/43/44 AF options

Telecontrol interface O4LA 5HYN589043-CA

Four-wire telephony interface O4LB 5HYN589133-CA

Two and four-wire telephony interface O4LC 5HYN589134-CA Universal telephony unit O4LD 5HYN589244-CA

ETL42/43/44 Channel 2 converter section 5HYN589135-CA

ETL41/42/43/44 Channel 1 converter section 5HYN589136-CA

ETL41/42/43/44 40 W power amplifier 5HYN589137-CA

ETL41/42/43/44 40 W power supply 5HYN589138-CA

Utility Communication Systems Internal wiring ETL41/42

A3 - 1 5HYN589126-TA

A.3 INTERNAL WIRING

ETL41/42/43/44 Back plane P7LB 5HYN589139-CA

Utility Communication Systems New introduction ETL41/42/43/44

A4 - 1 5HYN589126-TA

A.4 INTERSTAGE WIRING AND EXTERNAL CONNECTIONS

Interstage wiring and external connections 5HYN589132-WA

L.H.Side plate P7LA 5HYN693002

Side bracket P7LB 5HYN217005


A5 - 1 5HYN589126-TA

A.5 NEW INTRODUCTION

A.5.1 ETL TEST METER N3NL

General The test meter N3NL is a plug in module (optional), which can be used to make important DC and AC level measurements in carrier set type ETL41/42/43/44. The test instrument is to be plugged in the particular position of the equipment: ETL41/42/43/44 Tier P7LA Position 24 Measuring instrument DC and AC signal level with the frequency range of 0.3kHz….500kHz, can be measured by this instrument. With proper positioning of switch and input points provided on front panel, measurement is made easy in both DC and AC ranges. It works on 48V DC provided by module B5LA. DC measurement A DC voltage up to 50V (both positive and negative) can be measured with this meter. A DC voltage fed through input terminal ‘DC’ on front and appropriate range, either 10 or 50 volts selected by switch, helps to measure the input with better resolution. In case of positive voltage LED is lit, where as in case of negative voltage same LED remains OFF. AC measurement AC signal level of frequency between 0.3kHz to 500kHz can be measured. For better resolution of level measurement, three ranges viz. 0dB, -10dB and –40dB are provided.


A5 - 2 5HYN589126-TA

A.5.2 REMOTE SUBCRIBER APPLICATION WITH PAX_SUB AND 2_WINT

The main function of the PAX_SUB is to simulate a subscriber set towards the EPAX and the function of the 2-wint is to simulate an EPAX for the remote subscriber.

EPAX TO REMOTE SUBSCRIBER:

An EPAX has a number of subscribers connected over 2 wire lines. It can detect on-hook or off-hook condition of each subscriber by loop current detection. Initially a subscriber offers high impedance in on-hook condition. When the handset is lifted, low impedance is offered and a loop current flows through the instrument. Thus the EPAX detects this flow of current and knows that the subscriber is now off-hook. The EPAX then applies the dial tone. When the subscriber dials a number, the dialing pulses are detected by the EPAX and compared with the stored numbers. When the EPAX recognizes the called party, it checks to see if that called party is on-hook or off-hook. If the called party is off-hook, EPAX gives a busy tone to the calling party, but if the called party is on-hook, EPAX applies a ringer voltage. Now if the called party is a remote subscriber, then the PAX_SUB card detects the ringer voltage applied by the EPAX. The PAX_SUB converts the AC ringer voltage to DC, which operates an internal relay and applies M-signal i.e. it extends 0V to the remote subscriber side. This M-signal is applied as E signal to the 2-wint. The E signal activates the ringer and the remote subscriber instrument rings. When the called party lifts the handset, the 2-wint detects low impedance, cuts off the ringer and extends 0V over the M wire. This M-signal is applied to PAX_SUB over its E wire. When the PAX_SUB receives this signal, it offers low impedance to the EPAX and EPAX subsequently cuts off the ringer voltage and establishes 2-wire speech connection.

REMOTE SUBSCRIBER TO EPAX:

In on-hook condition, the remote subscriber offers high impedance to the 2wint. When the handset is lifted, low impedance offered causes a current to flow. The 2-wint then detects the off-hook condition and extends 0V over M wire. The PAX_SUB receives this signal over its E wire and offers low impedance to the EPAX. The EPAX then applies a dial tone. When the remote subscriber dials a number, the 2wint operates its relay over M wire in accordance with the dialed number. This is conveyed to the PAX_SUB over its E wire. The PAX_SUB operates its relay and the EPAX detects the dialed number. It applies ringer to the called party. When the called party lifts the hand set, EPAX stops applying ringer and establishes 2-wire speech connection.


A5 - 3 5HYN589126-TA

A.5.2.1 PAX SUBSCRIBER

General

This card is meant to be interfaced with the 2-wire port (subscriber side) of the PAX. With the help of this interface card, the PAX can be interfaced to O4LC in ETL. This interface card will act like a telephone to the PAX and at the same time it will give signaling information to the communication equipment i.e. it will sense the ringer voltage and give M-signal. In addition to it, this card will give impedance variation depending on the E-signal. Therefore with the help of this card, use of expensive PAX interface modules like O4LD in ETL.

Description

This interface card behaves as a telephone instrument for the PAX when connected to the PAX-Subscriber side and provides the signaling information to the speech interface card with 2 wire E & M on the communication equipment end.

This card does the following functions:

1) Detects the ringer voltage put by the PAX and gives M-signal to the communication equipment.

2) It senses E-Signal from communication equipment and gives low impedance to the PAX.

3) Makes the 2-wire speech through from PAX to communication equipment when the necessary conditions are satisfied.

4) Gives dialing information to the PAX depending on the variation in E-signal received from the communication equipment.

Technical Specification

1. No. of PAX to Communication interfaces: One

2. Input:

a. Speech In: 2 Wire Interface (PAX subscriber Side).

3. Output:

a. Speech Out: 2-Wire Interface

4. Compatible for using at the subscriber side of a Standard PAX whose ringer voltage should be in range 55 Vrms to 70 Vrms.

5. Signaling:

Extension of M-Output of PAX_SUB card by extending +ve supply to the communication equipment by relay contact with max rating 1A/60V.


A5 - 4 5HYN589126-TA

Extension of E-Input of PAX_SUB card by extending +ve supply from communication equipment loop current 10-15mA.

6. Mechanical Specification: 190 x 95 x 50 mm

a. (length x breadth x height)

b. Weight 0.45 Kg

7. Power Supply: 48 VDC +ve grounded.

(+20% to -10%)


A5 - 5 5HYN589126-TA

A.5.2.2 2-WINT INTERFACE

General

This card is to facilitate the connection of a standard 2 wire telephone to the PLC equipment. It generates the signaling required for a telephone which other wise has to be done by using a Exchange. This therefore avoids using a costly ring tone generator or an EPAX for the purpose of signaling.

Description

2-wint is connected to the PLC equipment as shown in drawing (fig: 1). Here the telephone instrument is connected to green connector. –48 VDC is used as the power supply and is connected to green connector named –48v & +0v. a) Outgoing Call:

When the telephone handset is lifted it gives a low impedance path and hence relays pick-up. Contact of the relay extends 0v to terminal 8 (signaling-M). This signal is use to shift the pilot.

b) Incoming Call: For incoming call the 0v is extend at terminal 4 (signaling-E). On extending the 0v, the circuit generates pulses. These +ve pulses tend a relay to pick up and enable the ringer voltage for about 60v rms. When relay picks up, the ringer voltage is connected to the telephone through contacts, and the telephone starts ringing. Now if telephone is lifted it gives a low impedance path and hence relays picks-up and the contact prevents the operation of relay after telephone is lifted.

Technical Specifications

1. Compatible for use with standard 2-wire telephone

2. Ringer voltage: 55V RMS to 65V RMS

3. Speech In: -6dB (Internal level)

4. Speech Out: 0dB (Internal level)

5. Telephone interface: 4 way plugging connector

6. Power Supply: 48VDC positive grounded

7. Interface to Communication equipment: 2W E&M using 4 way plugging connector

8. Extension of M: Output of 2wint to Communication equipment by extending +ve supply i.e. earth when telephone is off-hook.

9. Extension of E : Input of 2wint from Communication equipment by extending +ve supply i.e. earth when ringer inside 2wint is to be enabled.

10. Mounting arrangement: On an aluminum channel inside the cabinet.


A5 - 6 5HYN589126-TA

11. Dimensions: approx 190 x 95 x 50 (length x breadth x height) mm

12. Weight: approx 0.75KG

Modes of connectivity

• Remote subscriber application using EPAX with O4LD and 2-wire remote subscriber using O4LC with 2-wint. (Refer Fig: 1)

• Remote subscriber application using O4LC with PAX Subscriber card at the Exchange side and 2-wire remote subscriber using O4LC and 2-wint. (Refer Fig: 2)

• Hot line application using O4LC with 2-wint at both the ends. (Refer Fig: 3)

• Fax connectivity using O4LC with 2-wint at both the ends (Refer Fig: 3)

(Note: In this case; O4LC jumper is set for 3.4KHz)

Fig. 1

2 WINT_FOX TO O4LC CONNECTIONS:

+48V to cabinet-48V to cabinet

ETL

APPLICATION: REMOTE SUBSCRIBER USING O4LD(PAX SIDE), O4LC, 2WINT_FOX

side

e.g.201

2 Wire

-48V0V

SP1SP2

TEL

Subscriber (2W)

EPBX

2 WINT

PAXO4LD

EM

SubscriberRemotee.g.202

2 WINTO4LC

V9LA FOR O4LC

HY(6a)SIG GND(6b)

2W

M(9a)E(10a)

SIG GND (9b)(10b)

ETL 2 Wire

E&M

(1b)(1a)

2 Wire


A5 - 7 5HYN589126-TA

EPBX O4LC ETL 2 WINT2 Wire

E&M

-48V0VEM

2 WireCom. Equp.

-48V to cabinet+48V to cabinet

M(9a)

HY(6a)SIG GND(6b)

2W

E(10a) SIG GND (9b)(10b)

V9LA FOR O4LC

PAX_SUB

PAX_SUB TO O4LC CONNECTIONS:

2 WireO4LCETL

APPLICATION: REMOTE SUBSCRIBER USING PAX_SUB, O4LC, O4LC, 2WINT_FOX

(1a)(1b)

2 Wire

e.g.201 e.g.202Remote

Subscriber

2 WirePax_Sub

PAX

Pax_Sub 2 Wire

E&M2 Wire

Subscriber

Fig. 2


A5 - 8 5HYN589126-TA

2 WINT O4LC ETL

E&M

2 Wire 2 WINT2 Wire

E&M

FAX FAX

-48V0VEM

SP1SP2

TEL

-48V to cabinet+48V to cabinet

M(9a)

HY(6a)SIG GND(6b)

2W

E(10a) SIG GND (9b)(10b)

V9LA FOR O4LC

2 WINT

FAX

2 WINT TO O4LC CONNECTIONS:

FAX SETTINGS:

MODE:- F/TRING DELAY:- 01F/T RING TIME:- 20 SECONDSEASY RECEIVE:- OFF

3400 Hz:- GD,GE,GH2 WIRE TELEPHONE ADAPTOR:- SA,SB

O/P LEVEL:- O4LC S4 RHI/P LEVEL:- 2 WIRE S2

O4LC JUMPER SETTINGS:

2 OR 2/4 WIRE OPERATING MODE:- TA

MAKE:- BROTHER FAX-275

2 Wire2 WireO4LCETL

(1a)(1b)

Fig. 3


A5 - 9 5HYN589126-TA

4 Wire in

Hybrid

Signalling out 'E'

4 Wire out

Speech control

2 Wire in/out

Tel. signalling in 'M'

4W ETL TABLETELEPHONE

3

50V

V9LA X307

5b

1a

PAX

3b

2

1

6

7

Rx

Tx Test Tone

5b

5a

4b

4a

+ 10b

10a+

-

IN O4LC

WITH TTX PRINT

9b

1a

3a

8b

8a

1b

6b

6a

2a

2b

0V9a

V9LA

0V

-12V

-12V

0V

0V

-12V

O4LC

1.8k

2W

-48V 10b

0V 1a

A5.3 ETL TEST TONE INTERFACE - TTX

General

TTX is the Test tone interface card. It on O4LCa/O4LBa, facilitate to connect 4 wire table telephone to ETL.

Principle

Test tone of ETL is interfaced to 4 wire telephone for calling.

Operation

In this application the 4-wire telephone is extended to the control room table and the test tone is used for signaling purpose. This is a hotline telephone where the mouthpiece and the earpiece are directly driven by the O4LC internal circuit. For signaling purpose, the test tone is shifted. When the button in the telephone is pressed, the TTX card generates the calling signal using the transistors. At the receiver side, 0 V is extended through the transistor when there is an incoming call.

This sub-print is inserted in connector X4 on module O4LCa/O4LBa.

Interconnection between 4-wire calling Telephone & ETL

Fig: 4


A5 - 10 5HYN589126-TA

A5.4 UNIVERSAL SPEECH INTERFACE CIRCUIT (USIC)

General

The Universal Speech Interface Circuit is a child board which is mounted on O4LC module for FXO/FXS (Remote Subscriber) & Hotline functionalities on board. Therefore no external devices for such functionalities are required. By selecting the appropriate jumpers, the specific function can be implemented. In case, the simple O4LC operation is required, the USIC can be isolated by removing the jumpers on the USIC board.

The USIC is connected to the O4LC board via a ribbon cable that carries the power supply and signal/speech lines to the USIC. The ribbon cable can be fitted in any direction without restrictions.

The following figure indicates the location of the jumpers on USIC and O4LC.

Fig. 5

SA SB SC SD SE SF SG SH

PA PB PC PD PE PF PG PH J

JO JU

USIC BOARD

O4LC Module


A5 - 11 5HYN589126-TA

Programming Chart

Jumper Voice Service USIC O4LC

FXO End (EPAX End)

PA, PB, PC, PD, PE, PF, PG, PH

JU

FXS End (Remote Subscriber End)

SA, SB, SC, SD, SE, SF, SG, SH

JU

Hotline SA, SB, SC, SD,

SE, SF, SG, SH JU

For normal O4LC operation (2/4 wire E&M), place jumper at J and JO and the USIC should be isolated by removing all the USIC Jumpers. These jumpers should be placed at the spare jumper location provided on the O4LC board.

Modes of Operation 1. 4 Wire E&M EPAX Trunk Line (Normal O4LC operation)

Fig. 6 2. FXO/FXS (Remote Subscriber) Application With USIC

Fig. 7 EPAX

USIC

O4LC

ETL

2 WIRE

USIC

O4LC

ETL

2 WIRE

4 WIRE E&M

EPAX

USIC

O4LC

ETL

USIC

O4LC

ETL

EPAX

4 WIRE E&M


A5 - 12 5HYN589126-TA

3. FXS/FXS ( Hotline ) Application With USIC

Fig. 8

O4LC Termination on V9LA Terminal Block (only for USIC application) - a. Connection of EPAX to O4LC for FXO application

Fig. 9

USIC

O4LC E

TL 2 WIRE

USIC

O4LC

ETL

2 WIRE

EPAX 2 Wire Subscriber Line (1a)

(1b)

(2a)

(3b)

V9LA for O4LC

(10a)

(9b)


A5 - 13 5HYN589126-TA

b. Connection of 2 wire phone to O4LC for FXS/Hotline application

Fig. 10

2 wire Phone

2 Wire Subscriber Line (1a)

(1b)

(2a)

(3b)

V9LA for O4LC

(10a)

(9b)

ETL41 Manual En

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