CSC162 Manual.pdf

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C:\Pmsbp\CSC 162 dt 13.10.2007 CSC-162 Numerical Transmission Line Protection Equipment Manual

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SIFANG MAKE BCU-CSC162 ManuaL

Transcript of CSC162 Manual.pdf

  • C:\Pmsbp\CSC 162 dt 13.10.2007

    CSC-162 Numerical Transmission Line

    Protection Equipment Manual

  • C:\Pmsbp\CSC 162 dt 13.10.2007

    CAUTION1) This manual applies only to CSC-1622) Please read the manual carefully and with the specification of the

    installation, adjustment, testing, operation and maintenance.3) To prevent damage to equipment, dont plug-hot-plug any unit of the

    equipment, touching the chips and components in printed circuit board.4) Please use the testing equipment and devices which comply with the

    relevant standards for test and detection.5) If any abnormity occurred in the equipment or unusual maintenance

    needed, promptly contact with the agents or our service hotline.6) The operation password is: 8888.

    WARNING1) During hot-line operation of equipment ,certain parts of this equipment are under high voltage. Severe personal injury or significant equipment

    damage could result from improper behavior.2) Only qualified personnel should work on this equipment or in vicinity of the equipment. These persons must be familiar with warning & service procedure described in this manual, as well as with safety regulations.3) Prerequisites to proper & safety operation of the equipment are proper storage, setup, installation, operation & maintenance of the equipment.4) In particularly cases, the general rules & safety regulations according to relating standards(e.g. IEC, National standards or other International standards) for work with high voltage equipment must be observed.

    COPYRIGHTAll rights reserved.Registered trademark

    are registered trademark of Beijing Sifang automation co., ltd.

  • C:\Pmsbp\CSC 162 dt 13.10.2007

    CONTENTS1. Introduction ................................................................................................................. 1

    1.1 Application................................................................................................................... 1

    1.2 Features ....................................................................................................................... 1

    1.3 Functions ..................................................................................................................... 2

    2. Design .......................................................................................................................... 5

    2.1 Mechanical structure.................................................................................................. 5

    2.2 Dimensions.................................................................................................................. 6

    3. Technical data ............................................................................................................. 7

    3.1 General data ................................................................................................................ 7

    3.2 Function data..............................................................................................................11

    4. Hardware functions .................................................................................................. 12

    4.1 Hardware arrangements........................................................................................... 12

    4.2 Operations of complete units .................................................................................. 12

    5. Protection functions................................................................................................. 15

    5.1 Whole structure of protection program.................................................................. 15

    5.2 The protection basic elements ................................................................................ 15

    5.3 Monitoring function .................................................................................................. 24

    5.4 Other logic of pilot protection ................................................................................. 28

    5.5 Pilot protection.......................................................................................................... 30

    5.6 Four zones distance protection .............................................................................. 34

    5.7 Zero-current protection............................................................................................ 37

    5.8 Direction over current protection ........................................................................... 39

    5.9 Over voltage protection............................................................................................ 40

    5.10 Undervoltage protection........................................................................................... 40

    5.11 Breaker failure protection ........................................................................................ 41

    5.12 Autoreclose ............................................................................................................... 42

    5.13 Broken Conductor Function .................................................................................... 46

    6. Installation and commissioning .............................................................................. 47

    6.1 Unpacking & repacking ............................................................................................ 47

    6.2 Mounting .................................................................................................................... 47

    6.3 Check before power on ............................................................................................ 47

    7. Operation ................................................................................................................... 48

    7.1 Safety precautions.................................................................................................... 48

    7.2 Dialog with the equipment ....................................................................................... 49

    7.3 Setting the functional parameters........................................................................... 53

    7.4 Annunciations ........................................................................................................... 62

    7.5 Testing and commissioning .................................................................................... 65

    7.6 Commissioning using primary tests....................................................................... 74

    7.7 Putting the equipment into operation..................................................................... 76

    8. Maintenance .............................................................................................................. 77

    8.1 Routine checks ......................................................................................................... 77

    8.2 Relacing the back-up battery................................................................................... 77

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    8.3 Fault tracing............................................................................................................... 77

    8.4 Repairs ....................................................................................................................... 77

    8.5 The notices during operation .................................................................................. 77

    8.6 Manipulation after replacing software or CPU....................................................... 78

    8.7 Manipulation after replacing software or MASTER module................................. 78

    8.8 Manipulation after replacing input or output module ........................................... 78

    8.9 Manipulation after replacing AC module................................................................ 78

    8.10 Several illuminations................................................................................................ 79

    9. Storage....................................................................................................................... 80

    10. Ordering.83

    10.1 Selection and ordering data.84

    10.2 Ordering data84

    10.3 Accessories..85

    11. Appendix.................................................................................................................... 85

    A Terminal diagram ................................................................................................................. 85

    B Communication Protocol Tables........................................................................................ 86

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    1. Introduction

    1.1 Application

    CSC-162 numerical transmission lines protection equipment applicable to 132kVand lower voltage transmission lines. The product consists of primary protectionnamely 4 zones distance protection, 1 stage Definite time and Inverse time zerocurrent protection, 1 stage Definite time and Inverse time over-current protection, 2stages over-voltage protection, 2 stages under-voltage protection, circuit breakerfailure protection and three phase auto-re-close etc, as shown in Table.1-1.Table.1-1 Main function and arrangement

    Main function and arrangement

    Type4 zones phases-Phase distance andground distanceprotection

    Definitetime andInversetimezero Seqcurrent

    OvervoltageandUndervoltage

    Definitetime andinversetime overcurrent

    Circuitbreakerfailure

    ThreephaseAuto-Re-close

    CSC-161/2

    1.2 Features

    The equipment has characteristics as follows: The microprocessor combined 32 bits DSP with MCU, high performancehardware system ensures the parallel real-time calculation in all components of theequipment.

    Protective functions, man-machine interface and also communications functionsare completely independent in equipment. This improves the reliability and makesdebugging installation, maintenance easier.

    Internal module is designed in such a way that a comprehensive real-time self-monitoring is performed.

    Dual A/D sampling in analog circuit, performing real time self-testing.

    Latest checking methods are used which can detect coil performance inenergized circuit. Therefore failure of the relay is identified easily The equipmentprovides periodical automatic testing.

    Disturbance recorder with larger capacity, (memory up to 4M bytes), can recordmore than 5 records. Optional event format or wave format is provided when therecords need to be printed. Fault wave disturbance records can be easily

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    extracted through serial port or Ethernet port and saved in COMTRADE format

    1000 event records which are date and time tagged are stored in non volatilememory to ensure that the data are not lost when DC supply fails.

    The relay can record protection operating process, logic flow and variouscalculated values. Our CSPC software can be used for viewing the above and alsothe recorded fault data and for analyzing disturbance records via RS-232 serialport on the relay front fascia

    2-channel high speed reliable electric Ethernet ports (optional optical fiberEthernet ports), 2-channel Lon-Works ports, RS-485 port and series printing portare provided; the user can select any of these according to the requirements. Theprotocol supports IEC60870-5-103, IEC61850 or CSC-2000 of Sifang Company,for interface with substation automatization system and protection managementinformation system.

    Liquid crystal display with backlit is provided to display various messages suchas current, voltage, power, frequency, Strip State, setting zones etc. The menu iseasy to operate. Four shortcut keys are set to finish operation with one key forlocal operator.

    1.3 Functions

    Tele-Protection scheme (distance protection)

    Distance protection is the primary protection for transmission line. Relay is suitablefor 2 types of channel aided schemes viz, permissive under reach mode andpermissive over reach mode. It consists of directional distance element, directionalzero-sequence and negative-sequence element. Directional distance elementconsists of directional phase to earth distance element and phase to phasedistance element.

    Distance protection (Z)

    Both phase to phase distance protection and phase to earth distance protectionare provided in CSC-162 Distance protection protects the transmission line andhas a backup protection for the power system. This protection has four settablezones; in addition, every zone can be enabled or dis-enabled via binary settings.When VT fuse fails , distance scheme is blocked, thereby avoiding the mal-operation.The distance characteristic is polygonal. Power swing blocking (PSB)

    In 150ms after the abrupt current startup element operates, or when power swingstartup element or zero-current startup element operates, the executing programwill directly go into the logic part of power swing blocking.For asymmetric faults detection element, Zero-sequence and negative-sequencecurrent can distinguish fault from swing. The criterion is described as below.|I0|>m1|I1| or I2>m2|I1|

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    For three-phase fault detection element, the method distinguishing fault frompower swing:1. Within time , if R < K RMin (1800, TZMAX, ) is satisfied, it is determined thatfault occurs in power system.2. Within time , if R K RMin (1800, TZMAX, ) is satisfied, it is determined thatswing occurs in power system.

    Zero-current protection (3I0)

    This protection function is a backup protection for the transmission lines and thepower system. The protection is one stage definite time 3I0>. The zero-currentprotection Function can be enabled via binary settings.

    Inverse time zero current protection (3I0_INV)

    The directional element of inverse time zero current protection can be enabled ordisabled via binary settings. Its characteristic equation is as shown below;

    Id - fault current.T0_factor - Time factor of inverse time zero-current.N0 - Index of inverse time zero-current.3I0_INV - current setting of inverse time zero current.T0_INV - delay time setting of inverse time zero current which can meet therequirement that inverse time zero current co-operates with different protection.Inverse curves can be obtained according to the following settingN0=0.02 and T0_factor=0.14 Standard inverse (IEC Standard)N0=1 and T0_factor=13.5 Very inverseN0=2 and T0_factor=80 Extremity inverse.

    Over current protection (OC)

    This protection function is a backup protection for the transmission lines and thepower system. The protection is one stage definite time I>. The over-currentprotection Function can be enabled via binary settings.

    Inverse time over current protection (OC_INV)

    The directional element of inverse time over current protection can be enabled ordisabled via binary settings. Its characteristic equation is as shown below;

    Id - fault current.Toc_factor - Time factor of inverse time over current.Noc - Index of inverse time over current.

    T0_INV

    1)_03

    (

    _0

    0

    +

    =N

    INVI

    Id

    factorTT

    Toc_INV

    1)_

    (

    _+

    =

    Noc

    INVIoc

    Id

    factorTocT

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    Ioc_INV - current setting of inverse time over current.Toc_INV - delay time setting of inverse time over current which can meet therequirement that inverse time over current co-operates with different protection.Inverse curves can be obtained according to the following settingNoc=0.02 and Toc_factor=0.14 Standard inverse (IEC Standard)Noc=1 and Toc_factor=13.5 Very inverseNoc=2 and Toc_factor=80 Extremity inverse.

    Over voltage protection Uph-e> (OV)

    The protection comprises 2 stages Uph-e >. The phase voltage is measureddirectly at the VT. The overvoltage protection function can be enabled via binarysettings.

    Under voltage protection Uph-e< (UV)

    The protection comprises 2 stages Uph-e .It can be started by internal protective tripping orexternal via binary input.

    Auto-reclose (AR)

    CSC-162 protection system has three-phase auto-reclose. For any fault on theline, all the three poles will be tripped, and all the three poles will be re-closed.This function can be enabled via binary settings.

    Broken Conductor

    CSC-162 relay has broken conductor function, if the necessary condition aresatisfied, relay can give alarm and trip output.

    On-load measurement

    The on-load measured values generated in the unit such as current, voltage,phase angle, etc. can be displayed at the LCD or by means of a PC.

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    2. Design

    2.1 Mechanical structure

    The enclosure for equipment is 19 inches in width and 4U in height accordingto IEC 60297-3.

    The equipment is flush mounting with panel cutout and cabinet.

    Connection terminals to other system on the rear.

    The front panel of equipment is aluminum alloy by founding in integer andoverturn downward. LCD, LED and setting keys are mounted on the panel.There is a serial interface on the panel suitable for connecting a PC.

    Draw-out modules for serviceability are fixed by lock component.

    The modules can be combined through the bus on the rear board. Both theequipment and the other system can be combined through the rear interfaces.

    Fig.2-1 CSC-162 protection equipment view

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    2.2 Dimensions

    Dimension drawings for CSC-162 are shown in Fig.2-2.

    Fig.2-2 flush-mounted enclosure of 162 with panel cutout (dimensions in mm)

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    3. Technical data

    3.1 General data

    Analog input and output

    Nominal Frequency 50 HzCurrent Inputs

    Rated current IN 1 A or 5 ACurrent Overload Capability per Current InputThermal (rms.) 2 IN continuously

    10 x IN for 10s70 x IN for 1s

    Voltage Inputs

    Rated Voltage UN 110/3Voltage Overload Capability in Voltage Path per InputThermal (rms.) 1.2 UN continuously

    1.4 UN 10s3.1.1 Power supply

    Voltage Supply ( to be mentioned before Purchase order)Rated auxiliary voltage UDC 110V DC 220V DCPermissible voltage ranges 88V~121V 176V~242V

    3.1.2 Binary inputs and outputs

    Binary inputs

    Variant QuantityCSC-161/2 19

    Rated voltage range 110V/ 220V DC

    Binary outputs

    Variant Trip contacts Quantity Alarm contacts QuantityCSC-161/2 48 NO contacts 16 NO contacts

    Rated voltage range 110V/ 220V DC

    3.1.3 Communications interfaces

    Operator Interface

    local Connection type RS-232 Ethernet RS-485Medium of connection Electric Electric electricType of connector DB25 RJ45 twisted-pairType of data transfer Serial Serial serialSpeed of communication 9600bps 10/100Mbps 9600bps~38400bpsDielectric level III III IIIMaximum cable length 10m 110m 1.2km

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    Functions supported bythis port

    RS-232:Printsetting, faultreport,waveform report

    See setting,fault report,waveformreport

    see setting, faultreport, waveformreport

    Rear port for

    substation automation

    2 Ethernet 2 RS-485

    Communication protocolCSC2000 or IEC 60870-5-103 or IEC 61850

    CSC2000 or IEC 60870-5-103 or IEC 61850

    Medium of connection Either optics or electric ElectricType of connector RJ45 Twisted-pairSpeed ofcommunication

    10/100Mbps 9600bps~38400bps

    Dielectric level III IIIMaximum cable length 110m 1.2kmNote: Optical port is optional by order.3.1.5 Other general data

    Other General data of the equipments see table 3.Table 3 General data of the equipments

    No. Item Class/rated According

    to standards

    Note

    1 Environment conditions

    1.1 Ambient temperature -10C~+55C1.2 Extreme range of

    ambient temperature-25C~+70C

    1.3 Atmospheric pressure 80 -110kPa1.4 Operative ranges of

    auxiliary energizingquantities

    (80% -110% )UN

    1.5 Relative humidity 75%1.6 Storage temperature -10C ~ +40C

    IEC 60255-61988 (GB/T14047-1993IDT )

    2 Rated parameters

    2.1 Rated value of voltage 110V or 220V2.2 Rated value of current 1A or 5A2.3 Rated value of

    frequency50Hz

    3 Burden

    3.1 rated burden AC currentcircuit 1VA

    AC voltage circuit0.5A

    DC power supplycircuit: 50W

    DL/T 478-2001

    Specificratingdefined byManufacturerin IEC60255-61988

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    4 Thermal property

    4.1 Thermal of short andlong time

    AC current circuit2 In -continuously10 x IN for10s70 x IN for1s AC voltage circuit1.2 UN-continuously1.4 UN for10s

    DL/T 478-2001

    5 Electrical insulation

    5.1 Insulation resistance 100M IEC 60255-52000(GB/T 14598.3-2006,IDT)

    5.2 Insulation resistance indry heat

    1.5M DL/T 478-2001 No definedin IEC60255-5

    5.3 Dielectric voltage AC 2kV Ui63V1kV Ui

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    IEC 61000-4-37.4 Fast burst disturbance 4 class

    communicationport --2kV

    others ports--4kV

    IEC60255-22-4(GB/T14598.10-1996,IDT)IEC 61000-4-4

    Harsh more3 class ofIEC 60255-22-4

    7.5 Surge disturbance 4 class communicationport --2kV

    others ports--4kV

    IEC 60255-22-5,IEC 61000-4-5

    Harsh more3Class of IEC60255-22 -5

    7.6 Conducted disturbanceof RF

    3 class 10V IEC 60255-22-6IEC 61000-4-6

    7.7 Power frequencymagnetic fielddisturbance

    5 class 100A/m IEC 61000-4-8 No definedin IEC60255-22

    7.8 Pulse frequencymagnetic fielddisturbance

    5 class 1000A/m IEC 61000-4-9 No definedin IEC60255-22

    7.9 Damped oscillatorymagnetic disturbance

    5 class 100A/m IEC 61000-4-10 Actual up to120A/m Nodefinedin IEC 60255-22

    7.10 interruptions in auxiliaryenergizing quantities

    50ms GB/T 8367-1987(eqv IEC60255-11IEC 61000-4-11

    7.11 Electromagneticemissionlimits

    IEC 60255-25(GB/T14598.16-2002,IDT)

    8 safety

    8.1 Insulation cooperation ClearanceAnd creepageDistance

    IEC 60255-5:2000GB 16836-1997

    8.2 Maximum temperatureof material

    According with theStandard

    GB 16836-1997

    8.3 Flammability ofinsulation materials

    V 0 class IEC 60950GB 16836-1997

    8.4 Protection againstElectric shock

    I class IEC 60536GB 16836-1997

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    9 Trip relay contact

    9.1 Capacity of contact cutout

    50W

    9.2 Current of long time 5A

    3.2 Function data

    3.2.1 Tele protection for Distance protection

    Operation time: permission mode: 40ms.3.2.2 Distance relay

    a) Resistance setting range: 0.01 - 40(5A), 0.01 - 200(1A).Reactance setting range: 0.01 - 60(5A), 0.01 - 300(1A).b) Transient overreaching of zone 1 of distance relay: 5%c) Operating time of zone 1 of distance relay: 30ms when fault occurs within 0.7times setting valued) Measuring tolerance of fault locator (not including errors caused by externalfactors): +3% when fault current is greater than 0.01 In at earth fault, error willbecome bigger when fault occurs with greater path fault resistance.3.2.3 Zero-sequence element

    a) Setting range: 0.1In -20In.b) Transient overreaching of Zero-sequence current: 5%c) Forward direction-operating zone of zero-sequence power directional element:18 arg (3I0/3U0) 1803.2.4 Over current relay

    a) Setting range: 0.1In - 20In.b) Measuring tolerance: 3%c) Forward direction-operating zone of zero-sequence power directional element:

    -90 arg (U/I) 303.2.5 Over-voltage relay

    a) Setting range: 1V - 120V.b) Measuring tolerance: 3%3.2.6 Under-voltage relay

    a) Setting range: 1V - 60V.b) Measuring tolerance: 3%3.2.7 Auto re-closure

    a) Angle error of synchronization check: 3b) Voltage error of synchronization check: 0.7 Un 3%c) Measuring tolerance of low voltage detector: 0.3 Un 3%3.2.8 Time element

    a) Setting range: 0s - 10s error grade: 0.01sb) Measuring tolerance of Setting: 1.5% or 20ms

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    4. Hardware functions

    4.1 Hardware arrangements

    3 4 5 6 7 8 9 10 11AC CPU MASTER DI DO1 DO2 DO3 DO4 POWER

    Alternatingcurrent

    Relay

    Manage

    Digital Input

    Digital O

    utput1

    Digital O

    utput2

    Digital O

    utput3

    Digital O

    utput4

    45 20 40 20 20 20 20 20 35

    Fig.4-1 Arrangement diagram of the CSC-162system modules

    4.2 Operations of complete units

    CSC-162is configured with 9 modules as shown in Fig.4-1 including AC module,CPU module, MASTER module, DI module, DO1 module, DO2 module, DO3module, DO4 module, POWER module.

    4.2.1 Alternating Current module (AC)

    The AC module functions are to transform the secondary signals of voltage andcurrent transformers in power system into electric weak signals, and performisolation and anti-interference. The AC modules of CSC-162are the same, thewiring terminal at rear panel is X3. There are 9 analog signal transformers in CSC-161/2, used respectively to transform UA, UB, UC, UX, IA, IB, IC 3I0 and IN. There aretwo types of current transformer: Rated current 5A with linearity range 500mA -150A and rated current 1A with linearity range 100mA - 30A (please indicateclearly when order the product). Please pay attention that IN is the polarityterminal while IN is not. Rated phase value of voltage transformer is fixed to

    110/ 3V.

    4.2.2 CPU module (CPU)

    Combined DSP with MCU, the 32-bit microprocessor with 1M bytes flash memoryand 64 bytes RAM is employed to run programs in chip completely, and keep thedata bus in a chip. There is a CPU module in the CSC-162system. CPU1 performssampling, A/D transform, transmission analog data and input information,judgment of the protection theory, fault recorder and software and hardware self-testing etc.

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    In order to backup data and test A/D by the protection itself, every AC analogcircuit is divided to two channels to be sampled two analog quantities such as Iaand IaR for the current of phase A, Ib and IbR for the current of phase B. Theanalog quantities with postfix R such as IaR and IbR etc. are used to backup.

    4.2.3 Management module (MASTER)

    This module is a management and communication module, and its wiringterminal is X3 at rear panel. It carries out communication and informationexchange between the protection system and external equipments such as MMI,a PC, monitor and control system, engineer station, RTU and printer etc, andtransmits remote metering, remote signaling, SOE, event reports and record data.According to requirement, double LON net ports, three electric Ethernet ports(optional optical Ethernet interface) and double RS485 ports can be set in mastermodule to meet different substation automation system and RTU. In addition,time synchronization by GPS function can be also set to meet time regulationwith network mode or impulse mode. A series printer port is also reserved.Note: Two groups of optical Ethernet can be selected according the userrequirement.

    4.2.4 Digital Input module (DI)

    The input module 1 wring terminal at rear panel is X6. It is used to connect theinput signals and alarm signals such as the auxiliary contacts of the circuitbreaker (CB) etc.Each of input modules has two groups input circuits and self-testing circuits, so allinput circuits can be performed real time self-testing. The power supply of 24Venergizing input module can be input directly, another group input need to beconnected, 220V or 110V power can be used.

    4.2.5 Digital Output module (DO)

    CSC-162is developed 4 DO module .The wiring terminal of DO1 module at rearpanel is X7, that of DO2, 3 and 4 module is X8, X9 and X10 respectively. DOmodules mainly provide tripping contacts, pickup breaker failure protection,pickup auto reclosure and alarm contacts etc, which can be output directly frommodules with great performance against interference. CARR SEND-1 CH-1 onoutput X8 is speedy contacts, which is used to cooperate with communicationinterface device and energized by 24V. CARR SEND-2 CH-1can be can beenergized by 220V or 110V.

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    4.2.6 Power supply module (POWER)

    The power supply module with DC inverters module wiring terminal at rear panelis X11. Its input power is DC 220V or 110V (indication when ordered), and itsoutputs are five groups power supplies.

    1. + 24V two groups provided: Power for inputs and outputs module2. 12V: Power for A/D3. + 5V: Power for all CPU

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    5. Protection functions

    5.1 Whole structure of protection program

    Software of CPU protection includes main program, sampling interruption serviceroutine and fault detection routine.Main program is running under normal operation to perform hardware self-testing,setting solidified and transmission reports upward etc. Sampling interruption serviceprogram is active in a sampling interval time to implement data sampled, waverecord and fault detected by abrupt current etc. Whenever the fault detector elementsoperate, fault detection program is executed to run all protection logic and judge CTcircuit open or not etc. If any abnormal element is detected, a relevant alarm signaland report will be given.For the general alarm signals (ALARM II), only the signal is sent out to clue theoperator to examine and repair. For the serious alarm signal threatening theprotection security and reliability (ALARM I), once the signal is sent out, theprotection output circuit is blocked.When fault occurs in power system, fault detection program does not return to themain program until it has finished all relevant protection functions required to meetthe conditions of the whole reset.5.2 The protection basic elements

    5.2.1 Startup element

    Startup element main function is to detect faults, start the protection relay andenergize positive power supply for the output relay. Once startup element operates, itdoes not reset until the all activated conditions return to normal reset mode.Startup element includes current abrupt startup, zero-sequence current startup, theloss of static stability startup, low-voltage startup element in weak-source andautoreclose startup element. The fault detection program is picked up and thepositive power supply for the output relay is energized when any startup elementoperates.5.2.1.1 Abrupt current of phase-phase element I

    Abrupt current phase-phase element is the main startup element that can sensitivelydetect most of faults. Its criterion is as follows

    i> I_abrupt Or 3i0> I_abrupt

    where i= || iK- iK-T|-| i K-T - iK-2T || means AB,BC or CA, K is thecurrent sampling timingT=24 samples per cycle (K-T) is the sampling timingbefore one cycle from timing K, (K-2T) the sampling timing before two cyclesfrom timing K,

    3i0 is abrupt zero-current value,I_abrupt is the setting value of abrupt current.

    The abrupt current element operates when any phase-to-phase abrupt currenti or zero-sequence abrupt current 3i0 continuously exceed the setting I_abrupt.

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    5.2.1.2 Zero-sequence current startup element

    Besides abrupt current startup element, zero-sequence current element is also ableto overcome the inadequate sensitivity problem of abrupt current startup element atfaults with high resistance (up to 100 for 220kV, up to 300 for 500kV). As anauxiliary startup element, it operates with 30ms delay. Its criterion is as follows:

    3I0 > 0.9*I0setWhere 3I0 is three times zero-sequence current,

    I0set is the minimal value of the following values(1) The setting value of the zero-sequence current,(2) The setting value of inverse time zero current,

    5.2.1.3 The static stability detector

    To ensure the proper operation during loss of static stability state, the loss of staticstability detector is consideredIts operating conditions are described as below.(1) All currents of phase A, B and C are bigger than the current setting of I_PS

    and the abrupt current elements have not operated.(2) All impedances of phase-to-phase AB, BC and CA enter into zone of distance

    relay, and the abrupt current elements have not operated.Any of the above conditions has been validated for 30ms, power system is regardedin the loss of static stability state, then, the startup element operates, the protectionprogram is switched to power swing blocking module, at the same time, ZSTARTUP or I_PS STARTUP and RELAY STARTUP are reported.

    5.2.1.4 Lower voltage startup element (detailed in weak-source part)

    When one end of the protected line is weak-source system, lower voltage can beused to startup protection for permission mode. Its criterion: Single-phase voltage isless than 30V or phase-to-phase voltage is less than 50V and the relay receivessignal.

    5.2.1.5 Auto re-close startup element

    Protection tripping and the contacts of CB can cause autoreclose. Detailed inautoreclose part 5.16.

    5.2.2 Phase selector

    Using integrated phase selector detect various fault types, phase selector can pickout the faulted phase for selective-phase tripping.Abrupt current phase selector is used at the beginning of fault after abrupt currentstartup, later; sequence fault components phase selector is used. Both abrupt-current phase selector and sequence fault components phase selectors are notapplicable to weak-source system and feeder terminal line where low voltage phaseselector is employed.

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    5.2.2.1 Abrupt current phase selector

    Abrupt current phase selector employs phase-to-phase differential current IAB, IBCand ICA to detect the faulted phase by comparing the value of these currents. The amplitude of phase-to-phase differential current IAB, IBC and ICA at differentfaults are shown in Tab.5-1 below.(Where + means the bigger one, ++ the biggest one, means the smaller one)

    Table.5-1 Phase Slected I

    A B C AB BC CA ABC

    IAB + + ++ + + ++

    IBC + + + ++ + ++

    ICA + + + + ++ ++

    IAB, IBC and ICA can be sorted into the biggest, the bigger and the smaller, thenthe fault selection result can be implemented according to Tab.5-1.

    5.2.2.2 Sequence current phase selector

    Steady state sequence current phase selector mainly uses the angle relation of zero-and negative- sequence current to detect the fault phase with an additional methodbased on phase-to-phase impedance. Theoretical analysis have demonstrated that, compared with phasor I0a, I2a locatesat area of -30~+30when A-phase earth fault occurs or BC-phase earth fault doeswith a smaller resistance, furthermore, I2a lags behind I0a close to 90 with theresistance increasing. Six phasor areas can be divided according to the anglerelation of I2a/I0a as shown in Fig.5-1.

    I 0a

    +300

    - 300

    +90 - 900 0

    +150 - 15000

    AN, BCN

    ABN

    CN, ABN

    CAN

    BN, CAN

    BCN

    Fig.5-1 Phasor areas of steady state sequence phase selector 1. +30~ -30 conforms to AN or BCN 2. +90~ +30 conforms to ABN 3. +150~ +90 conforms to CN or ABN 4. -150~ +150 conforms to CAN 5. -90~ -150 conforms to BN or CAN 6. -30~ -90 conforms to BCN

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    Corresponding phase-to-phase faults are affirmed directly in the above areas of (2),(4) and (6). On the other hand, in phasor areas of (1), (3) and (5), there are single-phase and phase-to-phase both fault types which are always independent to eachother and can be differentiated by phase-to-phase impedance calculation. If phase-to-phase impedance is bigger than its setting, then phase-to-phase fault isimpossible, single-phase-ground fault can be confirmed, otherwise phase-to-phasefault will be done.

    5.2.2.3 Low voltage phase selector

    Low voltage phase selector mainly meets phase selection of the relay fixed at weak-source end where both of the above phase selectors can not select faulted phase. IfVT circuit does not open, low voltage phase selector can be put into operation. Itscriterion is as below.

    a) Any one of phase voltage is less than 30V and other two phases voltage arelarger than 50V, then the single phase with lower voltage is decided.b) If phase-to-phase voltage is less than 30V phase-to-phase fault is decided.

    5.2.3 Distance element

    Distance protection consists of measuring unit and directional unit.5.2.3.1 Operating characteristics of distance element

    Every zone of the distance element is of the polygonal characteristics as shown inFig.5-2. For 4 zones phase-to-phase distance relay, RSET and XSET of zone 1, 2,3and 4 is respectively set to R1_pp, R2_pp, R3_pp, R4_pp, X1_pp, X2_pp, X3_ppand X4_pp. For 4 zones phase-to-ground distance relay, RSET and XSET of zone 1,2, 3 and 4 is respectively set to R1_pe, R2_pe, R3_pe, R4_pe, X1_pe, X2_pe,X3_pe and X4_pe.

    Where XSET is set according to the protected range and RSET is set according toavoiding load impedance (under general instance), which meets differentrequirements to enhance the resistive tolerance to high path fault resistance for shortline and to improve the ability of avoiding load impedance for long line. Thereactance line of polygon is inclined to an obliquitous angle 7(as shown in Fig.5-2)to enhance the ability to prevent the relay from overreaching at forward externalfaults.When fault occurs after reclose or manual close, based on the characteristics shownin Fig.5-2, the impedance operating characteristics includes a small rectangle area atthe center of coordinates as shown in Fig.5-3. This is called impedance-offsetcharacteristics that can ensure that faults near the bus can be reliably cleared. Zone3 of distance element has offset characteristics when three-phase fault occurs.

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    Fig.5-2 Fig.5-3

    Fig.5 operating characteristics of polygonal distance protection

    The values in the small rectangle operation area are shown in Tab.5-2.Tab.5-2

    SettingX is set as XSET/2, if XSET 1X is set to 0.5(In=5A) or 2.5 (In=1A), if XSET>1

    Setting The minimum among 8 times the above X andRSET/4

    Where XSET is the reactance setting of relevant elements, RSET is the resistancesetting of relevant elements.

    5.2.3.2 Measuring unit of distance element

    Based on differential equation arithmetic, measuring element calculates relevantcircuit impedance value with real-time voltage and current.For single-phase-to-ground impedance:

    U=L *

    )3( 0

    dt

    IKId X+ +R *(I+Kr3I0), = A, B, C.

    For phase-to-phase impedance: U=L dt

    dI+ RI, =AB, BC, CA.

    Where Kx = (X0-X1)/ (3X1), Kr = (R0-R1)/ (3R1).Measuring resistance R and reactance X (X =L=2fL) at relay location can beobtained by means of calculating the above differential equations.

    5.2.3.3 Directional unit of distance element

    Special directional elements are set to resolve dead zone for distance protectionwhen fault occurs near the bus. For symmetric fault, the memory voltage that is thepre-fault voltage is used to compare phasor with post-fault current to detect direction.For asymmetric fault near the bus, negative-sequence directional element is taken asdirectional element of distance relay. The operating conditions for distance relay areas below: The forward directional element operates, and measuring impedance lieswithin the setting polygon area.

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    5.2.4 Zero-sequence directional unit

    Zero-sequence current directional unit is composed of forward and reversedirectional elements whose operation areas are shown in Fig.5-4. The threshold offorward directional element can be set while that of reverse directional element cannot, whose sensitivity is automatically higher than forward element, and threshold is0.625 times that of the forward element.

    Area of forward directional element is 18 arg (3.

    I 0/3.

    U 0) 180

    Area of reverse directional element is -162 arg (3.

    I 0/3.

    U 0) 0

    18

    81 81

    3U0

    lm

    forward

    reverse

    Fig.5-4 Operation area of zero-sequence current directional element

    a Criterion of forward directional element is as below.Directional element lies in the forward directional operation area and 3I0>3I0SET.

    Where 3I0SET are the setting of inverse time zero-sequence current, and the settingvalues of of zero-sequence current 3I0.

    b) Criterion of reverse directional element is as below.Directional element lies in the reverse directional operation area and3I0>0.625*3I0SET.

    The zero-sequence directional element employs the 3U0 that is obtained by softwaresumming three-phase voltage.

    5.2.5 Negative-sequence directional element

    Negative-sequence directional element is taken as condition of enabling impedancedirectional element for asymmetric faults. Operation area is shown in Fig.5-5.

    Area of forward directional element is 18 arg (3.

    I 2/3.

    U 2) 180,

    Area of reverse directional element is -162 arg (3.

    I 2/3.

    U 2) 0.

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    18

    81 81

    3U2

    lm

    forward

    reverse

    Fig.5-5 Operation area of negative-sequence directional element

    5.2.6 Opening element of power swing blocking

    Power system is impossible to begin swing within 150ms after sudden-charge currentstartup element operating, therefore, during this time, all distance relays are settledto take on action, and power swing block need not be enabled. After the setting ofT_PS NO BLOCKING, all distance relays are settled to take on action, and powerswing block need not be enabled. After 150ms or the protection startup by loss ofstatic stability or zero-sequence current, the distance relay must be enabled by faultdetector to prevent mistake trip during power swing.Fault detectors for power swing blocking are different for asymmetric faults andthree-phase fault.

    5.2.6.1 Asymmetric faults detection element

    Zero- and negative-sequence current can distinguish fault from swing. The criterionis described as below.

    |I0|>m1|I1| or I 2>m2|I 1|Where m1 and m2 ensure that, during power swing, the mal-operation of the distanceprotection is not caused when external fault occurs under the most disadvantageousconditions of power system but asymmetric faults detection element can be operateswhen internal asymmetric fault occurs.When power swing happens, I0 and I 2 are close to zero, it is impossible for the aboveformula to come into being. When power swing and external fault occur, the smallerfault component current at the relay location cant meet the above formula. Whenpower swing and internal fault occur, I0 and I 2 will be big enough to meet the aboveformula. To keep the protection from mistake trip caused by the imbalance output ofzero- and negative-sequence current when the external fault is removed, theprotection has to operate in a certain short time delay.

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    5.2.6.2 Three phase fault detection element

    a) During power swing, measuring resistance or measuring impedance at therelay location is continuously changing with time, and sometimes the change isslow, sometimes the change is intensive, the change rate is decided by swingperiod and the machine angle . Curve 1 and curve 2 in Fig.5-6-(a) are thetrajectories of measuring resistance changing with time, where Rf is loadresistance component and Tz is swing period. Whether the trajectory ofmeasuring impedance is a line or a circular arc on R-X plane during powerswing, is decided by electromotive force of both terminals equivalent system, asshown in Fig.5-6-(b).

    R

    jX

    0

    Rm( t )

    Rf

    0 t

    Tz

    Zm

    a b

    1 2

    (a) Measuring resistance Rm. changing with time (b) the track of measuringimpedance on R-X planeFig.5-6 The trajectory of measuring impedance during power swing

    tO

    R f

    Rk

    Rm( t )

    t 1 t 2 t 3

    Fig.5-7 The trajectory of pre- and post-fault measuring resistance changing withtimeb) When fault occurs on the protected line, resistance component of measuringimpedance maybe changes due to electric arc elongated, but analysis andcalculation show that changing rate of arc resistance is far less than that ofresistance corresponding to the possibly biggest swing period noted up to thepresent. After short circuit, measuring resistance is resistance RK of shortcircuit, whose value hardly changes or almost keeps invariability, as shown in

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    Fig.5-7. The rule of measuring impedance is also similar.Contrasting Fig.5-6 with Fig.5-7, it can be seen that power system is determined tobe in the swing state if measuring resistance is always changing and exceeds athreshold value in a period of time. Therefore, the least change of resistance islooked over during power swing. It can be known from analyzing Fig.5-6 that theinstance of the least change of measuring resistance occurs in the followingconditions.

    (1) near =180(2) the biggest swing period TZMAX.And then, enlarge this part track of resistance change to be shown in Fig.11.

    180

    2/

    minR

    mR

    t

    TZMAX swing curve

    Fig.5-8The instance of the least change of measuring resistance

    It can be known from Fig.5-8 that a minimum changing resistance RMin (1800, TZMAX, ) is

    obtained corresponding to a time , in this way, for any swing period and any time period , allexist: R RMin (180

    0, TZMAX, ). Therefore, consider error and protection margin, take the

    following formula as criterion detecting swing.R KRMin (180

    0, TZMAX, ) (1)

    Reliable coefficient K is a less than 1. Surely, also consider equivalent system impedance SZ for

    (1). And, for a different regulated time , the corresponding RMin (1800, TZMAX, ) can becalculated.Concluding the above analysis, we can reason the method distinguishing fault from power swing:1. Within time , if R < KRMin (1800, TZMAX, ) is satisfied, it is determined that fault occursin power system.2. Within time , if R KRMin (1800, TZMAX, ) is satisfied, it is determined that swing occursin power system.When fault occurs, it is possible that formula (1) is satisfied due to time too small, however, can be increased to relax the restrained condition R < KRMin (180

    0, TZMAX, ), and to make

    use of it to identify fault gradually. c) When fault suddenly occurs on the protected line, if the angles between twosources do not reach 180, or three-phase fault occurs outside the swing center, themagnitude and angle of pre- or post-fault impedance must have great suddenchange. Based on this characteristic, distance element can be enabled quickly whenthree-phase fault occurs in power system without serious swing or under theconditions that swing does not occur after protection pickup for 150ms.

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    5.3 Monitoring function

    5.3.1 Software monitoring

    5.3.1.1 Loss of measure voltage detection

    Interruptions in the secondary circuits of voltage transformers is detected andreported by the device. Two criteria are set to detect VT circuit opened and both ofthem have delay time. Only under normal operation and without any element startup,they are put into operating. Hardly does the circuit-opened detector stop operatingwhen any startup element operates, and it is not enabled until all system reset.Criterion a: The sum of three phase voltages is not equal to

    zero,...

    cba UUU ++ >7V(r.m.s)

    This is used to detect one phase or two phases circuit open.Criterion b: When VT is connected to bus, if any phase voltage Ua, Ub or Uc isless than 8V, VT fuse fail is confirmedWhen VT is connected to line, if any phase voltage Ua, Ub or Uc is less than8V, and any phase current is larger than 0.04In or circuit breaker (CB) is in theclosed state, VT fuse fail is confirmedThe additional current condition of criterion b is to avoid undesired alarms before CBis switched on when VT is on the line side. The additional condition which CB is inthe closed state is to avoid that the system can be unable to give an alarm in case ofloss of voltage for three phases when the line current is too small (for example, CBlying at another terminal of the line is off).

    When VT circuit is opened, VT Fail is reported, and all distance units, negativesequence directional unit, abrupt directional element, directional over current unit andzero current unit with direction are forbidden to operate. Measure voltage will becontinuously supervised in order that each element can be automatically put into theoperation again as soon as the voltage returns to the normal.

    VT Fail judge logic is shown below in Fig.5-9:

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    Relay startup

    3U0 >7V

    NO DI CB OPEN

    1

    OR1

    &

    AND2

    &AND1

    VT_bus1

    OR2

    Relay test

    Ia(b,c) >

    0.04In

    Ua(b,c) < 8V

    &

    AND3

    &AND4

    &

    AND5

    VT FAIL

    Fig.5-9 VT Fail judge logic

    5.3.1.2 CT failure/current unbalance

    To prevent the relay from wrong trip, interruptions in the secondary circuits of currenttransformers is detected and reported by the device. When the zero-sequencecurrent is always larger than the setting value of 3I0 for 12s, CT Fail will be reportedand zero-sequence current protection will be blocked.

    5.3.1.3 Check Phase-sequence for voltage and current

    In normal condition of power system, whether AC circuits of three phases areconnected in right sequence or not can be distinguished by phasor comparison ofthree phases current and voltage. If they are in abnormal sequence, 3-PH SEQ Errwill be reported.

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    5.3.1.4 Check 3I0 polarity

    By comparing value and phasor of calculation 3I0 (IA+ IB + IC) with that of 3I0 externalconnected, whether the polarity of external 3I0 is connected in reverse or not can bedifferentiated, if it is in reverse, 3I0 Reverse will be reported.

    5.3.1.5 Check the third harmonic of voltage

    If the third harmonic voltage exceeds 4V, Harmonic Alarm will be reported with 10sdelay time, but the protection is not blocked.

    5.3.1.6 Line reference voltage check

    Under the auto-reclose condition of three-phase mode, if there is current through lineor not, input of auxiliary tripping contact of CB, which indicates CB is in the closestate. The following methods can check the line voltage in good condition.When AR_check Sync or AR_check low U is set for automatic reclosure modes, ifthe voltages between both sides of CB can not meet the setting synchronismcondition, which is confirmed with 14s delay time, SYN Voltage Err is reported. Thesystem supervises extractive voltage on real time.

    5.3.1.7 Check auxiliary contact of circuit breaker (CB)

    If there is input signal of auxiliary contact of CB, and corresponding phase hascurrent, which is confirmed with 2s-delay time, CB Open Err is reported.

    5.3.1.8 Check for the illogicality of setting

    a) In function of pilot protection such as< POR mode > and < PUR mode >, if bothmodes are put into operation at the same time, Pilot FUNC Alarm is alarmed.b) In function of automatic recolsure of equipment, if any two kinds of modes are putinto operation at the same time among < AR_No check >, < AR_check low U > and , AR FUNC Alarm is alarmed.c) Choose VT mode, If two kinds of modes are put into operation at the same time and < VT_bus>, VT Choice Alarm is alarmed. If for < VT_line >and is not put into operation, relay is put into operation for < VT_bus>.d) In function of distance protection, Z4 put into operation, if two kinds of modes areput into operation at the same time < Reverse_Z4 >and < Forward_Z4 >, Z4 ChoiceAlarm is alarmed.

    5.3.1.9 Check of the CSC-162relay system

    a) CPU module check. CPU module performs self-testing to its memories, analogchannels and program during power on, parts of the above are checked by itself inreal time during the system running. If any of them is confirmed to be incorrect, alarmwill be given, and the protection will be blocked.

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    b) The sampled data can be checked with each other in real time due to theredundancy of double A/D channel for one analog quality. If the difference betweentwo channels exceeds the setting limit, one of the double channels is regarded asfault one.c) Each I/O module performs self-testing during power-up and real-time self-tests.Self-testing checks input channel, output channel, memories and code areas etc.Self-testing of input channel is performed by bit changing simulation. Self-testing ofoutput channel includes coil tests and outer circuit tests. The tests are very thoroughwith wide range, if any failure is confirmed, alarm is given.d) Real-time self-testing of communication ports. CPU module and MASTER moduleperform real-time self-tests of communication among all kinds of function modules.When interrupt communication is detected, alarm is given.e) MASTER module performs self-testing at power-up and real-time self-testing thatcheck memories, program areas and relevant communication with the outside. If anyabnormal event is detected, alarm will be given. The setting and strap messagesstored in this module are checked with each other.f) Real-time supervision for DC power supply.g) CRC checks for the setting etc.

    5.3.2 switch-on-to-fault protection (SOTF)

    The input of auxiliary tripping contact of CB lasts 10s, later I operates, and then thesystem regards this condition as manual closure of the CB. If no fault is detected, 1slater, the whole system resets. If fault is detected, instantaneous trip function put intooperation.Distance relay use impedance element to detect fault, zero-current relay operateswith 100ms delay, when fault occurs during switch-on-to-fault.When switch-on-to-fault line occurs, if the binary setting of distance relay is enabled,the distance relay will accelerate to operate. Six loops of impedance will becalculated, if any of them is located in the area of operating characteristics with offsetregion, the distance relay trips with no delay time.

    5.3.3 Tripping after automatic reclose

    If the fault still exists after automatic reclose, then the protective elements will re-tripthe circuit breaker.The equipment requires three auxiliary tripping contacts of segregated phaserespectively as three binary inputs. For 3/2 bus connection scheme, each phasetripping contacts of two breakers must be series at first, and then the series contactsof each phase are connected to the corresponding binary input of the equipment.When the equipment has detected CB opened, and any phase current is larger than0.1In(three-phase reclose mode) or the input of auxiliary tripping contact disappears,the equipment thinks that line has reclosed.

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    5.3.4 The conditions of relay reset

    When all the following conditions have been meet for 5s, the whole relay resets fromfault dealt program.

    a) Six loops of impedance are outside the 4 zone of impedance.b) Zero-current is less than the setting of zero-current startup value.c) All three-phase currents are less than the setting I_PS of loss of static

    stability.5.4 Other logic of protection

    5.4.1 Logic after tripping

    After tripping commands sent out, the current of tripping phase is in the supervision.When tripping phase has not current, the protection system considers that CB hasbeen opened. If tripping phase always has current, the system output three-phasetrip signal with 150ms delay. After this, if any phase current lasts 150ms, three-phasefinal tripping command is issued. Later, if CB still in close state lasts 5s, three-phasefinal tripping failure alarm will be sent out, and the whole relay will reset.Trip command will be withdrawal as soon as fault is cleared. To ensure that CB tripsreliably, withdrawal command is impossible to be considered within 40ms after tripcommand sent out.When there is no current flowing through three phases for 12s after the output ofthree-phase trip command, the program routine jumps to the whole relay reset. Thedelay time of 12s is to believe that the most setting delay time for three-poleautoclosure is impossible larger than 10s.After tripping command output, the sending signal command (for permissive mode)does not return until tripping command has been withdrawal for 120ms in order toensure the tele protection of both terminals to operate reliably.

    5.4.2 Reverse directional elements

    Impedance directional element is set forward directional element. The threshold offorward directional element can be set while that of reverse directional element neednot whose sensitivity is automatically higher than forward element.

    The usage of the reverse directional element is as follows.

    a) Tele protection sends signal with 40ms-delay time when the directional elementschange from reverse direction to forward direction. It prevents relay wrong trippingwhen zero-sequence or negative-sequence power reversing flow during externalfaults cleared.

    b) In the protection logic for weak-source system, only all the forward and reversedirectional elements do not operate, the send signal element using low-voltagecould be put into operation.

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    5.4.3 Protection schemes for feeder

    If one side of the line is feeder, when forward fault for the relay at feeder side occurs,the fault characters are no longer same as that of two side source system. Toperform selective tripping function for a line with feeder, feeder tripping of pilotprotection must be put into operation.If feeder function is enabled, CSC-162can fit the following conditions.When internal faults occur, the local relay sends out permissive signal (permissivemode) in order that the relay at power source side trips quickly. The relay at weak-source side can correctly perform selective trip.Phase selector of the relay at weak-source end can meet the phase-selectionrequirements for line faults, and the relay can correctly perform selective trip. Even iffaults occur on load terminal line, the relay can either send out tripping commandquickly and exactly or select fault phase correctly.

    5.4.4.1 Logic of low-voltage pickup

    When abrupt current startup element does not pick up, if feeder function is enabled,relay starts up under the following conditions.

    a) Voltage is lower than 30V.b) Receiving signal.

    After pickup, the feeder relay will send signal (for permissive mode) quickly, andextend the signal 120ms to ensure the relay at power source side to trip quickly.

    5.4.4.2 The relay trip logic at feeder

    At feeder side, if the relay have picked up and the following conditions are satisfied,the relay of permissive mode sends permissive signal. If the setting of the relay atfeeder is enabled, the relay can trip after confirming permissive signal.

    c) At least one phase voltage or phase-phase voltage is less than 30V.d) Both the forward and reverse directional elements do not operate.e) Pickup time is less than 200ms.f) Receiving permissive signal for 5ms.

    5.5 Tele protection schemes for Distance protection

    It is applicable to two kinds of communication modes: permissive under reachmode (PUR) and permissive over reach mode (POR).

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    5.5.1 Pilot protection logic for permissive mode

    5.5.1.1 Overreach permissive

    CSC-162pilot protection logic for overreach permissive mode is shown in Fig.5-10.When internal fault occurs, the startup elements and zone 2 can operate, permissivesignal is sent out to the remote to permit the remote trip. If it is external fault thatoccurs on line, the forward directional element of one end of the line operates anddoes not receive permissive signal while that of another end of the line does notoperate and receive permissive signal, therefore, both ends cant trip.

    a) Internal faultoperates, relay trip for meeting following condition.1) Instantaneous trip if Zone 1 Operation2) Zone 2 + permission Signal from Remote end for 5ms.Zone 2 operates that permissive signal is sent out to the remote. b) External Fault

    Because the directional element near fault detects reverse direction, it does not sendpermissive signal to the remote. Although the remote relay can send signal, it cannotreceive the remote permissive signal, therefore, both of two sides do not trip.

    c) Power flow reversing for external fault The method to resolve this problem for the relay is that the relay sends signal with40ms delay time when the directional element operates from the reverse to theforward to avoid the period in which both sides are forward direction, and then bothsides trip after sending signal is confirmed with 15ms delay when internal fault occursagain.

    d) Protection schemes for feeder The binary setting Feeder_FUNC is enabled.

    1. For feeder end, abrupt current startup element cannot operates, the logic of thelow voltage is startup: If the relay at feeder end receives the remote permissive signal and operates, relay startup.2. For feeder end, abrupt current startup element operates, the operating logic ofthe relay is as below.

    Within 200ms after protection pickup, if operates, both theforward and reverse directional element at feeder end do not operate, and thepermissive signal has been received for 5ms, (sending signal) lasted for 120ms toensure the relay at power source end trips quickly, feeder end can also trip.

    e) The protection is not picked up, receives the remote signal < CARRRECEIVED > and there are < CB OPEN >, (send signal) can be done for 200ms toensure the remote pilot protection operates reliably.

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    Relay startup

    &AND-2

    Zone 2 operation

    Delay time 5ms

    Relay reset

    &AND-1

    &AND-4

    CARR Send signal

    &AND-5

    Trip three phase

    Single fault

    Multiphase fault

    &AND-6

    &AND-7

    Trip three phase

    Three phase fault

    &AND-8

    Permenent trip

    &AND-3

    Low voltage

    CARR Received

    &AND-9

    OR-2

    |0 120|

    CB OPEN

    &AND-

    11

    |0 200|

    OR-1

    Fig.5-10 CSC-162pilot protection for overreach permission mode logic

    5.5.2.2 Under reach permissive

    CSC-162pilot protection logic for under reach permissive mode is shown in Fig.5-11.When internal fault occurs, the startup elements and zone 1 can operate, permissivesignal is sent out to the remote to permit the remote trip. If it is external fault thatoccurs on line, the forward directional element of one end of the line operates anddoes not receive permissive signal while that of another end of the line does notoperate and receive permissive signal, therefore, both ends cant trip.

    a) Internal faultoperates, relay trip for meeting following condition.1) Instantaneous trip if Zone 1 Operation2) Zone 2 + permission Signal from Remote end for 5ms.Zone 1 operates that permissive signal is sent out to the remote.

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    b) External Fault Because the directional element near fault detects reverse direction, it does not sendpermissive signal to the remote. Although the remote relay can send signal, it cannotreceive the remote permissive signal, therefore, both of two sides do not trip.

    c) Power flow reversing for external fault The method to resolve this problem for the relay is that the relay sends signal with40ms delay time when the directional element operates from the reverse to theforward to avoid the period in which both sides are forward direction, and then bothsides trip after sending signal is confirmed with 15ms delay when internal fault occursagain.

    d) Protection schemes for feeder The binary setting Feeder_FUNC is enabled.(1) For feeder end, abrupt current startup element cannot operates, the logic ofthe low voltage is startup: If the relay at feeder end receives the remote permissive signal and operates, relay startup.(2) For feeder end, abrupt current startup element operates, the operating logic ofthe relay is as below.

    Within 200ms after protection pickup, if operates, both theforward and reverse directional element at feeder end do not operate, and thepermissive signal has been received for 5ms, (sending signal) lasted for 120ms toensure the relay at power source end trips quickly. Feeder end can also trip.

    e) The protection is not picked up, receives the remote signal < CARRRECIEVED > and there are < CB OPEN >, (send signal) can be done for 200ms toensure the remote pilot protection operates reliably.

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    Relay startup

    &AND-2

    Zone 1 operation

    Delay time 5ms

    Relay reset

    &AND-1

    &AND-4

    CARR Send signal

    &AND-5

    Trip three phase

    Single fault

    Multiphase fault

    &AND-6

    &AND-7

    Trip three phase

    Three phase fault

    &AND-8

    Permenent trip

    &AND-3

    Low voltage

    CARR Received

    &AND-9

    OR-2

    |0 120|

    CB OPEN

    &AND-

    11

    |0 200|

    OR-1

    Zone 2 operation

    Fig.5-11 CSC-162pilot protections for under reach permission mode logic

    Pilot direct trip function

    The pilot protection has input of B/LBB OPTD, it will give output Direct trip sendfor 200ms. If it has input of Direct trip RECV, it will give output Direct trip RECV.

    Direct trip RECV

    B/LBB OPTD

    Direct trip RECV

    0 200Direct trip send

    Input Output

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    5.6 Four zones distance protection

    The distance relay consists of 4 zones phase-to-phase and 4 zones phase-to-earthdistance elements, which is applied to remove phase-to-phase fault and singlephase-to-earth fault.Zone 1, zone 2, zone 3 and zone 4 of distance relay are controlled respectively to beon or off by the binary setting. Zone 4 of distance relay can be set to operate inforward or reverse direction.

    5.6.1 Some introductions of the program logic of the distance protection

    5.6.1.1 Power swing blocking

    After the abrupt current startup element operates, the protection switches theexecuting program to the fault processed part, the distance measurement element isinstantaneously opened for 150ms. Within 150ms, zone 1, zone 2, zone 3 and zone4 of distance relay are fixedly put into operation. The abrupt current startup elementoperates after 150ms , or when the loss of static stability startup element or zero-current startup element operates, before the setting of T_PS NOBLOCKING, theexecuting program will directly go into the logic part of power swing blocking. In thisperiod, four zones of distance relay must be enabled by fault detector of power swingblocking, that is, asymmetry faults are detected by asymmetry fault detector, threephase fault is detected by the impedance change rate detector (dR/dt)

    Four zones of distance relay are controlled by the setting to be selected whether theyare blocked during power swing. If the setting is set off, four zones of distance relayare put into operation without blocking all the time during power swing.During power swing, there is a special program module to detect whether powerswing quiets down or not, that is, if all zero-current elements, Power swing currentdetection element and six impedances of four zones of distance relay dont operate,after 5s, the whole system resets.

    5.6.1.2 Loss of Potential Measurement

    The distance relay exits after loss of measure voltage, and at the same time, themeasure voltage of VT is monitored continually. Once the voltage comes to thenormal, the distance relay will be automatically put into operation again.

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    5.6.2 Function of the distance relay as shown in Tab.5-4

    Tab. 5-4Item

    Zone

    binary settingZ_PSblocking

    Trip mode trip control

    Zone 1Blocked /unblocked

    Three phase tripthe setting ofZ1_FUNC

    Zone 2Blocked /unblocked

    Trip_no ARthe setting ofZ2_FUNC

    Zone 3Blocked /unblocked

    Trip_no ARthe setting ofZ3_FUNC

    Zone 4Blocked /unblocked

    Trip_no ARthe setting ofZ4_FUNC

    5.6.3The scheme logic of distance protection

    The scheme logic of distance protection is shown in Fig.5-12. a) The measure element is enabled to operate for 150ms after abrupt current

    startup, if the calculated impedance lies in zone 1 of the distance relay: Whether zone 1 of the relay is blocked during power swing or not is controlled

    by the setting Z1_PS blocking. If the setting Z1_PS blocking is set tooff, power swing blocking is disabled,. If the setting Z1_PS blocking is setto on, power swing blocking is enabled, distance relay are opened throughdetecting fault. Relay startup reclose after Zone 1 trip.

    b) If the calculated impedance lie in the operating area of zone 2: Whether zone 2 is blocked during power swing or not is controlled by thesetting Z2_PS blocking. If the setting Z2_PS blocking is set to off, powerswing blocking is disabled. If the setting Z2_PS blocking is set to on,power swing blocking is enabled. Relay dont startup reclose after Zone 2 tripwith delay time.

    c) Fault occurs in the range of zone 3: Whether zone 3 is blocked during power swing or not is controlled by thesetting Z3_PS blocking. If the setting Z3_PS blocking is set to off, powerswing blocking is disabled. If the setting Z3_PS blocking is set to on,power swing blocking is enabled. Relay dont startup reclose after Zone 3 tripwith delay time.

    d) Fault occurs in the range of zone 4: Whether zone 4 is blocked during power swing or not is controlled by thesetting Z4_PS blocking. If the setting Z4_PS blocking is set to off, powerswing blocking is disabled. If the setting Z4_PS blocking is set to on,power swing blocking is enabled. Relay dont startup reclose after Zone 4 tripwith delay time. Zone 4 can be select Reverse_Z4 or Forward_Z4,Reverse_Z4 mainly apply to blocking mode.

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    Four zones distance relay dont consider power swing blocking after abruptcurrent startup for the setting T_PS NOBLOCKING.

    e) Permanent trip for three-phase fault: Relay will permanent trip for three-phase fault.

    f) Switch-on-to- fault: If any impedance lies in the area of zone 1, zone 2, zone3, relay permanent trip immediately.

    Current change startup

    &AND-3

    I_PS startup

    Zone 1 -pe

    Zero-sequence current startup &

    AND-4

    &AND-6

    Trip three phase

    Single fault

    &AND-9

    Trip three phase

    Three phase fault

    &AND-10

    Permenent trip

    Zone 2

    Forward direction

    &AND-

    11

    Zone 4

    SOTF

    OR-4

    OR-6

    |150 0|

    OR-1

    Fault detect swing unblocking

    VT fail

    Zone 1 -pp

    Z1(2,3,4)_PS blocking

    &AND-2

    OR-2

    OR-3

    &AND-1

    &AND-5

    Zone 3

    OR-7

    |T2 0|

    |T3 0|

    |T4 0|

    &AND-8

    &AND-12

    Fig.5-12 Distance protection logic

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    5.7 Zero-current protection

    5.7.1 Configuration and principle

    One stage directional definite time and inverse time zero current protection are setduring three-phase operation. Directional element of zero current protection is fixed.Zero current is controlled to be on or off by the setting of 3I0_FUNC, and inversetime zero current protection is controlled to be on or off by the setting of 3I0_INVFUNC, Directional element of inverse time zero current protection is controlled to beon or off by the setting of 3I0_INV DIR.

    5.7.2 Inverse time zero current protection

    The directional element of inverse time zero current protection can be on or off viathe setting of 3I0_INV FUNC. Its characteristic is written as below:

    Where: Id fault current.T0_factor time coefficient of inverse time zero current.N0 Index setting of inverse time zero current.3I0_INV current setting of inverse time zero current.T0_INV delay time setting of inverse time zero current which can meet therequirement that inverse time zero current co-operates with different protection.Inverse curves can be obtained according to the following setting:N0 =0.02 and T0_factor =0.14 Standard inverse (IEC Standard)N0 =1 and T0_factor =13.5 Very inverseN0 =2 and T0_factor =80 Extremity inverse.

    5.7.3 Some explain about the program of zero current protection

    a) The polarity of 3U0The protection system employs the self-count 3U0 which is obtained by the sumof three phase voltages by means of software for the zero-sequence directionalelement to detect direction. If VT circuit is open, zero protection with directionalelement exits automatically.

    b) CT circuit openTo prevent sensitive zero current from maloperation caused by CT circuit open,the character that the zero-sequence voltage is zero in case of CT open can beemployed to block zero-current directional protection which may maloperate byzero- sequence directional element. Zero current will last for a long time as CTcircuit is open, if zero current is larger than the setting of 3I0 continuously for12s, CT Fail will be reported, and every stage of zero protection will beblocked.

    T0_INV

    1)3I0_INV(

    T0_factor

    N0

    +

    =Id

    T

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    5.7.4 Function of zero current protection as shown in Tab.5-5

    Tab.5-5

    Itemstage

    Directionalelement controlledby setting

    Tripping modecontrolled by setting

    Outputcontrol

    Definite time ofzero current

    fixed with direction Permanent tripthe setting of3I0_FUNC

    Inverse time ofzero current

    thesetting3I0_INVDIR is on or off

    Permanent tripthe setting of3I0_INVFUNC

    5.7.5The scheme logic of zero-current protection

    The scheme logic of zero-current protection is shown in Fig.5-13. After the abrupt current startup element or zero current assistant startup elementoperate, the protection system goes into the executing program to the faultprocessed. Definite time zero current and inverse time zero current are put intooperation under three-phase operation.

    Permenent trip

    3I 0> 3I 0

    SOTF

    | T0 |

    OR-3

    &

    Forward direction

    VT fail

    CT fail|12s 0| CT fail

    ALARM

    &

    &

    3I0

    3I0_INV DIR &

    |T_INV |

    3I0 FUNC

    3I0_INV FUNC

    Fig.5-13 zero current protection logic

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    5.8 Direction over current protection

    5.8.1 Configuration and principle

    This protection function is a backup protection for the transmission line and thepower system. The protection comprises one stage definite time over current andinverse time over current. The over current protection function can be applied to viabinary settings.Each phase current is compared with the setting value Ioc_pe after numericalfiltering. Currents above the associated pickup value are detected and signaled. Theprotection is blocked by directional element. Directional element is 90 connectionmode. Current of each phase is controlled by corresponding directional component.Following figure (Fig.5-14) is over current directional element(current lags and angleof voltage is positive).

    directional element I U

    A IA UBCB IB UCAC IC UAB

    Forward -90 arg (U/I) 30

    I

    U

    30

    forward

    Fig.5-14 over current directional

    After expiry of the associated time delays Toc_pea trip command is issued. Thefunction can be operation via a binary setting OC_FUNC ,and inverse time overcurrent protection is controlled to be on or off by the setting of OC_INV_FUNC,Directional element of inverse time over current protection is controlled to be on oroff by the setting of OC_INV DIR.. The over current function is permanent trip.

    5.8.2 Inverse time over current protection

    The directional element of inverse time over current protection can be on or off viathe setting of OC_INV FUNC. Its characteristic is written as below-

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    Where-Id fault current.Toc_factor time coefficient of inverse time over current.Noc Index setting of inverse time over current.OC_INV current setting of inverse time over current.Toc_INV delay time setting of inverse time over current which can meet therequirement that inverse time over current co-operates with different protection.Inverse curves can be obtained according to the following setting-Noc =0.02 and Toc_factor =0.14 Standard inverse (IEC Standard)Noc =1 and Toc_factor =13.5 Very inverseNoc =2 and Toc_factor =80 Extremity inverse.

    The following figure (Fig.5-15) shows the logic diagram for over current.

    Permenent trip

    I > I oc_pe| Toc |

    &

    Forward direction

    VT fail &

    &

    I

    OC_INV DIR &

    | T_INV |

    OC FUNC

    OC_INV FUNC

    Note: I is phase current of Ia, Ib, Ic. Fig.5-15 Over current logic

    5.9 Over voltage protection

    The relay comprises 2 stages over voltage function. The phase voltage is measureddirectly at the VT. The over voltage Function can be applied to via binary settings.Each phase voltage is compared with the setting value OV1_pe after numericalfiltering. Voltages above the associated pickup value are detected and signaled.After expiry of the associated time delays Tov1_pea trip command is issued. Thefollowing figure (Fig.5-16) shows the logic diagram for first stage over voltage. Thestage can be operation via a binary setting OV1_FUNC. Two stages over voltage ispermanent trip.

    Toc_INV

    1)_

    (

    _+

    =

    Noc

    INVIoc

    Id

    factorTocT

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    Permenent trip

    U>OV1_pe

    Tov2_pe

    U>OV2_pe

    Tov1_pe OV1_FUNC

    OV2_FUNC

    &

    &

    Note: U is phase voltage of Ua,Ub,Uc.

    Fig.5-16 Over voltage logic

    5.10 Under voltage protection

    The protection comprises 2 stages under voltage. The phase voltage is measureddirectly at the VT. The under voltage protection Function can be applied to via binarysettings.Each phase voltage is compared with the setting value UV1_pe after numericalfiltering. Voltages under the associated pickup value are detected and signaled.After expiry of the associated time delays Tuv1_pea trip command is issued. Thefollowing figure (Fig.5-17) shows the logic diagram for first stage under voltage. Thestage can be operation via a binary setting UV1_FUNC. Two stages under voltage ispermanent trip.

    VT fail

    U0.1In

    Initiate AR

    Tuv1_pe &

    U

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    any internal or external protection and at least one current is larger than I_CBF, thebreaker failure protection is initiated and the corresponding delay time T_CBF isSTART 3-PH CBF. When three-phase circuit breaker failure start up, single-phasecircuit breaker failure will be started up.

    Relay trip

    DI of Start CBF 3-PH

    1

    IA>I_CBF

    IB>I_CBF

    IC>I_CBF

    & T_CBF 3P_CBF startup

    CBF_ FUNC

    1

    Fig.5-18 Circuit Breaker Failure Protection logic Figure

    5.12 Autoreclose

    5.12.1 Autoreclose mode

    CSC-162protection system is provided with autoreclose whose performance is onlyto close the circuit breaker but not to select fault phase and trip.CSC-162protection system only have three phase autoreclose mode. In CSC-162relay you can setup control word AR_3p modeto enable auto re-close.AR_3p mode-if three phase trip, and relay then reclose regardless of the fault types,whether single-phase fault or multi-phase fault.CSC-162have 4 checking modes of reclose : AR_No check, AR_check Sync,AR_check low U and AR_CB3, you can select any one of them by control word toenable it , if you select one checking mode ,conditions must be satisfied ,soautoreclose can perform.

    5.12.2 Voltage and synchronism check

    When all three phases of the circuit breaker are open, three kinds of check mode areprovided as below.

    a. Synchronism check: If the line voltages and bus bar voltages are larger thanthe value of have voltage setting, and meet the synchronous conditions,synchronizing reclose can be performed.b. Low voltage check: If the line voltages are checked to be less than the value ofno-voltage setting, reclose can be performed. If the line voltages and bus barvoltages are all larger than the value of voltage setting, the check mode isautomatically turned to synchronism check to reclose.c. No check: Whatever the line voltage and bus bar voltage are, autoreclose is

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    performed.when relay only enable AR_3p mode,and dont select any reclosemode of AR_No check, AR_check low U and AR_check Syn,then relay thinkit is in AR_No check mode .Note : (1)The threshold of low voltage check is 17V of rated voltage and that of

    voltage check is 40V of rated voltage, the angle of synchronism checkcan be set.(2)The voltage phases of synchronism check or low voltage check neednot be set, as the protection system can automatically identify, that is tosay, if autoreclose check mode is set to synchronism check or no-voltagecheck, the voltage phases is identified according to the voltage from thebus and line. When CB is closed, if the voltage phases whose voltagecan be satisfied with synchronism check cant be found, SYN VoltageErr is alarmed, and A-phase voltage is regarded as the synchronismvoltage.The voltages provided for the relays are always from the bus VT, so thereference voltage is referred to the voltage at terminal Ux for low voltagecheck or synchronism check.

    (3) When three check modes of autoreclose are all disenabled, the faceplateof LCD displays: check mode: No check.

    5.12.3 Charge and discharge of autoreclose

    To avoid repetitious autoreclose, a special timer with charging interval for the settingT_Reclaim is set to perform the function of charge and discharge. Only after chargehas been finished, autoreclose is enabled while charge is not finished, autoreclose isdisenabled. a) The charge time counter starts when the following conditions are satisfied. (1) There is no input of CB OPEN. (2) The startup elements of autoreclose do not operate. (3) No input of blocking autoreclose. b) The charge time counter is reset when the following conditions are satisfied. (1) External signals of blocking reclose are received. (2) Discharge is performed when the reclose command is output. (3) There is no input of CB OPEN or INITIATE 3PH A/R when charge is notfinished.

    (4)During autoreclose startup, the opened phase has current.

    5.12.4 Autoreclosure pickup

    Two kinds of pickup mode are set by relay internal trip, digital input of other relay tripor the auxiliary contacts of CB. a) Auto re-close startup caused by other relay tripInput terminal INITIATE 3PH A/R. The relay must return immediately after asuccessful tripping and reclosure is started after the contacts return from the closeposition.

    b) Internal tripping signals have pick up autoreclose, therefore, the input terminal

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    for INITIATE 3PH A/R which need not be connected again from external contacts.Only distance zone 1 and pilot relay operate to startup reclose. Other relays operateto block AR.

    c) Autoreclose shot caused by the auxiliary contacts of CBAutoreclose shot caused by the auxiliary contacts of CB is mainly considered for CBoccasional mal-open. The CB occasional mal-open of three-phase can be set by thecontrol word to decide whether to pick up reclose or not.In addition, no accelerated contacts are given after successful reclose caused by theauxiliary contacts of CB.

    5.12.5 Reclose

    When autoreclose is picked up, the following functions are performed before reclosesignal output.

    a) Continue to detect the digital input of A/R BLOCK. If it is received, timecounter of charging will be cleared, and the program of autoreclose willbe reset.

    b) Voltage check is performed according to the setting of voltage andsynchronism check, if voltage condition is not satisfied, the counter oftime delay of autoreclose is cleared.

    c) If reclose command is sent out, autoreclose module is reset in 4s.When autoreclose is picked up, the discharging conditions are satisfied,autoreclose module is reset immediately and reclose is disabled.If it is caused by unsatisfied synchronism conditions or the others that reclose cannot be performed successfully, autoreclose model will be reset with a certain timedelay. Under three-phase autoreclose mode, it is the setting delay of three-phaseautoreclose +12s.The voltages provided for the CSC-162protection system are always from the busVT, so the reference voltage is referred to the voltage at terminal Ux for no-voltage check or synchronism check. If the line voltages and bus voltages are alllarger than the value of voltage setting, the check mode is automatically turned tosynchronism check.

    5.12.6 Blocking AR condition

    Relay will block reclose when any conditions occur, at the same time, it gives outputof AR Lockout Alarm.

    a) Distance zone 1 operates when equipment has digital input of CARRIERFAIL.b) Distance zone 1 or pilot operates when the fault occur again after reclosing .c) Distance zone 1 or pilot operates when equipment has digital input of A/RBLOCK .

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    5.12.8 Both series of autoreclose operating at the same time

    The CB closed state are detected according to trip and current, when two s