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DMRC Electrical Standards & Design Wing DMES-T/0005

SPECIFICATIONS FOR THREE PHASE 33 kV / 415 V AUXILIARYTRANSFORMER

Draft-2Dated: 5 Sep 2016

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DELHI METRO RAIL CORPORATION LIMITED

DMRC ELECTRICAL STANDARDS &DESIGN WING (DESDW)

SPECIFICATION NO.DMES- T0005/ DMRC-E-TR-TRANSF-05

SPECIFICATIONS FOR THREE PHASE 33 kV/415 VAUXILIARY TRANSFORMER

Issued on:

Date Stage5th Sep 2016 Draft - 2

DELHI METRO RAIL CORPORATION LTD.7th Floor, B-Wing, Metro Bhawan, Fire Brigade Lane,

Barakhamba Road, New Delhi –110 001.




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Previous Record of specification

Stage DateDraft -1 04/02/2015Draft - 2 05/09/2016




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Table of Contents

1. Detailed Description of the equipment and its application in DMRC.................................... 4

2. GOVERNING SPECIFICATIONS:....................................................................................... 5

2.1 Standards .......................................................................................................................... 52.2 Abbreviations ................................................................................................................... 5

3. Technical requirements........................................................................................................... 6

3.1 Accessories....................................................................................................................... 73.2 Temperature Protection .................................................................................................... 73.3 Transformer Values.......................................................................................................... 73.4 Transformer Cubicle ........................................................................................................ 83.5 Terminal arrangements..................................................................................................... 93.6 painting............................................................................................................................. 93.7 Insulation of windings.................................................................................................... 103.8 Name Plate Details ......................................................................................................... 10

3.8.1 Rating Plate fitted to the transformer...................................................................... 103.8.2 Rating Plate fitted to the transformer enclosure ..................................................... 11

3.9 Capitalization and Penalty.............................................................................................. 114. MAINTENANCE & LIFE.................................................................................................... 13

5. DATA SHEET - AUXILIARY TRANSFORMERS............................................................ 14

5.1 AUXILIARY TRANSFORMER 200 KVA and 630 KVA................................................ 145.2 AUXILIARY TRANSFORMER 1600 KVA AND 2000 kVA........................................... 15

5.3 AUXILIARY TRANSFORMER 2500 kVA/3000 kVA and 3000/3500 kVA ................... 176. TEST SHEET .......................................................................................................................... 18

6.1 AUXILIARY TRANSFORMERS .................................................................................... 186.2 Partial Discharge Test ........................................................................................................ 186.3 Environment, Climate & Fire behaviour Class Test .......................................................... 18




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1. DETAILED DESCRIPTION OF THE EQUIPMENT AND ITS APPLICATION INDMRC - 33 KV / 415 V, 3 PHASE AUXILIARY TRANSFORMERSThe Auxiliary Transformers, also referred to as Auxiliary Station Transformersare required to supply the power requirement at 415 / 230 V of various electricalequipments, systems and appliances. Mainly these comprise of power requiredfor lighting, fans, air-conditioning, Lifts, Escalators, Pumps, Signage boards,control and monitoring circuits, battery chargers, space heaters in the switchgear/ panels etc.This specification defines the main technical characteristics required for the33000 / 415 V dry type transformers to be used in auxiliary substations (ASS),auxiliary main substations (AMS) or as required. This specification is applicablefor the transformers of power rating of following capacity which are generallyused in DMRC. This specification may be used for any other capacity in thisrange.:

Transformer CapacityAN (Air Natural) AF (Air Forced)

200 kVA N/A315 kVA N/A400 kVA N/A500 kVA N/A630 kVA N/A800 kVA N/A

1000 kVA N/A1600 kVA N/A2500 kVA 3000 kVA3150 kVA 4000 kVA

The transformer offered shall be complete in all respects with all parts andaccessories necessary for their efficient operation in sub stations. All such parts &accessories shall be deemed to be within the scope of this specification whetherspecifically mentioned or not.




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2. GOVERNING SPECIFICATIONS:

The dry type auxiliary transformer shall conform to IEC 60076-11 with specifiedvoltage as 33 kV/415 V.

2.1 STANDARDSThe transformer shall satisfy the following requirements and shall also complywith standards in force when the transformers are manufactured, particularlywhich are in the following table (Unless otherwise stipulated in the specifications,the latest version of the following Standards shall be applicable): -

Standard # DescriptionIEC 60076-3 Power transformers - Insulation levels, dielectric tests and

external clearances in airIEC 60076-11 Dry-type power transformers

2.2 ABBREVIATIONS IEC – International Electro technical Council

IS - Indian Standard

BS – British Standard

ASS – Auxiliary Sub Station

RSS – Receiving Sub Station

GI – Galvanized Iron




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3. TECHNICAL REQUIREMENTS: The details and specifications applicableto three phase 33 kV / 415 V auxiliary transformer are given below -The primary and the secondary windings shall be capable of withstanding asymmetrical three - phase short-circuit regardless of the tapping selected. Theshort circuit level at secondary side for various ratings of transformers shall be asspecified in the data sheet.

The terminals shall be of the 36 kV type. Conductors insulated at 36 kV realizedelta connection on primary side by using rigid conductors with suitable insulationsleeves. The secondary neutral shall be solidly earthed.

This equipment shall satisfy all the requirements for interchangeability, interlockability and functional control applicable to this type of equipment. It shall use atechnology and components identical to those of the equipment to be installed inthe Auxiliary sub stations.

Characteristics :

The magnetic circuit shall be in low-loss oriented-grain silicon steel sheet.

Climatic conditions indoor operationAmbient temperature for design 500COperation ContinuousWindings Aluminium for more than 200

kVA rating and Copper for 200kVA & less rating

Primary line voltage (across phases) 33 kVSecondary voltage, off-load 415 VInsulation rated voltage 36 kVFrequency 50 HzRated short duration separate source ACwithstand voltage (r.m.s.)

70 kV (for hv winding), 3 kV(for LV winding)

Rated lightning impulse withstand voltage(peak value)

170 kV

Connections Dyn11Cooling Air natural/Air forcedOff load tap link 0, ±2.5% and ±5%Class of insulation for all windings F Class for HV and LV windingClimatic/Environmental/Fire Class E2/C1/F1 (IEC 60076-11)




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3.1 ACCESSORIES Installed on rollers/ base channels Lifting rings Nameplate Grounding terminal of Transformer frame, enclosure and Core

The connection with different terminals of transformer shall be through C type orsuitable connector for sufficient clearances from transformer windingsHV connections of transformer shall be connected through insulated cables.HV terminals shall have suitable arrangement to provide sufficient clearance to33 kV class cables from transformer windings and transformer enclosure as perIEC 60076-3.

3.2 TEMPERATURE PROTECTIONTransformers shall be fitted with a temperature protection system that allowswinding temperatures to be monitored.

This shall consist of two sets of sensors placed on each low-voltage windingsignals of Alarm and Trip and for fan operation. These signals to be used forAlarm and Trip of upstream circuit breakers, for fan operation, and also forindication in SCADA.

An indicator and relay with 6 inputs channel as above shall be installed on thefront side of the transformer enclosure to indicate continuously the windingtemperature.

3.3 TRANSFORMER VALUESThe contractor shall confirm the following characteristics for each powerdistribution transformer:

Short-circuit voltage, No-load losses, Full-load copper losses at 950C Efficiency at 950C at different load conditions:

Full load: Power factor = 1 (Minimum efficiency: 98.4%)Power factor = 0.8 (Minimum efficiency: 98%)

The efficiency of transformer at ¼, ½, ¾, full load at unity and 0.8 PF forthese loads shall be more than 98%. Bidder in the offer shall meet theconditions of efficiency as above.




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3.4 TRANSFORMER CUBICLE

3.4.1 Transformers shall be installed in dismountable cubicle, made up of sheetsteel of minimum 2 mm thickness, Powder coated with provision of Louversand wire-mesh. The transformer enclosure shall be provided with cut outopenings protected with fine wire mesh to meet the IP rating and louvers onthese cut out openings. The transformers shall be supplied in a cubicle withenclosure having a degree of protection of not less than IP-31 and withoutany HV portions exposed. The door shall be provided with a mechanicalinterlocking system, to ensure that it is possible to open the door only whenthe protection circuit breakers on the HV side as well as LV side of thetransformer are in ‘open’ position and Earth switch on upstream 33 kV cableis closed. Also circuit breakers on the HV side as well as LV side of thetransformer should trip if somebody tries to open the door without openingthe HV & LV side breakers.

Minimum Clearance of any earthed part or enclosure from any live terminalof transformer should be as per IEC 60076-3.

The transformer should be tested with enclosure to meet temperature risetype test. The enclosure supplied shall be of similar design as used in thetemperature rise test.

Enclosure shall have inspection windows of minimum size of 400 mm x 400mm on both sides to view primary & secondary sides of the transformer.LED Lights inside enclosure on both HV and LV sides shall be providedinside enclosure for visual inspection from outside. Switch should beprovided on outer side of the enclosure to operate the lights.

The cubicle shall provide protection against direct contact with the powertransformer. It shall include connections for the HV lines from the protectionbay and connections for the low voltage circuit.

The transformer enclosure shall be designed and provided by thetransformer manufacturer along with the transformer.

3.4.2 Cable arrangement shall facilitate the exchange of the either of thetransformers without any difficulty, i.e. the cables shall be laid along eachside and connected to the transformer in such a way that it will not block thepassage for removal of any of the transformer during service. Thecontractor will provide suitable size stiffeners in enclosure for connection ofbus duct and to ensure that the enclosure does not deform due to Bus ductconnection. The panel shall not make any rattling sound and should beprovided with a rubber gasket as required.




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3.4.3 The cubicles shall be protected against fire by means of an ‘automatic firedetector and extinguisher system’, ‘Fire trace’ type or equivalent, completewith CO2 Gas cylinder / clean agent (Novec 1230, FM-200 and Argonite)approved by Chief Controller of Explosives, valves, flexible detection anddelivery system in the form of a flexible tube made of special polymer,capable of withstanding normal pressure and maximum pressure as perdesign of the system and applicable standards, suitably routed inside thetransformer enclosure for detection of fire. The gas cylinder shall be suitablymounted on the Transformer enclosure or on the floor near the transformerenclosure and shall be capable of flooding the cubicle with gas, within theshortest response time, not more than 10 seconds after the fire is sensedby the flexible detector tube.

The contractor shall submit the complete technical data of the system andshall obtain the approval of DMRC before ordering for manufacture oftransformer enclosure.

3.4.4 The bimetallic strip required for connection in any case shall be provided bythe contractor.

3.5 TERMINAL ARRANGEMENTSThe terminal arrangements for high voltage side shall be suitable forrequired size of cables. The terminal arrangement for Low voltage side shallbe suitable for required size of cables/Bus ducts. Suitable arrangementsshall be available for cable terminations so that the cable/Bus duct weightdoesn’t come on the terminals.The terminals on the primary side should be provided with protectionshrouds suitable for 36 KV.

3.5.1 The clearances of transformer terminals shall be as per IEC 60076-3. Themanufacturer shall submit the transformer drawings showing all theclearances and dimensions.

3.6 PAINTING

All steel surfaces shall be painted which shall be suitable for heavily pollutedatmosphere and shall be applied with rust proof and anti corrosive paint withcoatings of glossy oil & weather resistance non fading paint of colorRAL 7032.




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3.7 INSULATION OF WINDINGS HV windings should be cast resin moulded type, and LV winding shall be of pre impregnated with top and bottom properly

sealed by resin to protect from dust and moisture.

Insulation barrier sheet between LV and HV windings with appropriateclearance shall be provided of full height of windings.

3.8 NAME PLATE DETAILS

3.8.1 Rating Plate fitted to the transformer

Each transformer shall be provided with a rating plate of weatherproofmaterial, fitted in a visible position, showing the items indicated below. Theentries on the plate shall be indelibly marked (i.e. by engraving, stamping orby a photo chemical process).

a) Dry type transformerb) Number & year of latest IEC 60076c) Manufacturer’s named) Manufacturer’s serial numbere) Year of manufacturef) Insulation system temperature for each winding. The first letter shall refer

to high voltage winding, the second letter shall refer to low voltagewinding. When more than two windings are present, the letters shall beplaced in the order of windings from the high voltage to low voltage

g) No. of phasesh) Rated power for each kind of coolingi) Rated frequencyj) Rated voltages, including tapping voltages, if anyk) Rated currents for each kind of coolingl) Connection symbol

m) Short circuit impedance at rated current and at the appropriate referencedtemperature

n) Type of coolingo) Total massp) Insulation levels




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q) Degree of protectionr) Environmental classs) Climatic classt) Fire behaviour class

The rated withstand voltages for all windings shall appear on the rating plate.The principles of the standard notation are illustrated in clause 5 ofIEC 60076-3.

3.8.2Rating Plate fitted to the transformer enclosureEach transformer enclosure shall be provided with a rating plate ofweatherproof material, fitted in a visible position, showing the items shown in3.8.1 The entries on the plate shall be inedibly marked (i.e. etching,engraving, stamping or by a photochemical process).

3.9 CAPITALIZATION AND PENALTYThe transformers shall be designed for minimum losses. When comparingbetween different tenders the present value of the capitalized cost of losses inthe transformers shall be added to their financial bid by the following formula

PW = K*365*24* C (W ir + b² Wcu)/1000

Where

- PW is the present worth (in INR) of annual capitalized cost of losses at 8%rate of interest over 25 years

- K is the present worth factor (8% interest, 25 years) = {(1+0.08)25 – 1}/{0.08*(1+0.08)25} = 10.675

- C is the cost of the kWh (in Indian Rupees) = Rs. 6.15 - Wir is the ironlosses in Watts at normal voltage and main tapping

- Wcu is the full load copper losses in Watts at normal voltage and maintapping at 95°C

- b is the load factor of transformer = 50 %

Thus PW = 10.675*365*24* 6.15 (W ir + b² Wcu)/1000PW = 575.10 (Wir + 0.25 Wcu)

In case the transformer losses during tests are found greater than the valuesguaranteed in the offer, a consolidated penalty shall be paid by the contractor,according to the following formula (any tolerance from the declared value on upperside will not be considered):




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575.10 (dWir + 0.25 dWcu)

Where,- dWir and dWcu are the differences between the test values of iron losses at full

voltage and copper loses at full load on one transformer at main tapping and thevalues guaranteed in the offer.




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4. MAINTENANCE & LIFEThe transformer should be designed for best service life in the industry and not less than 40yrs for all types of installation & under prescribed environmental conditions.




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5. DATA SHEET - AUXILIARY TRANSFORMERS

5.1 AUXILIARY TRANSFORMER 200 KVA, 500 KVA AND 630 KVAS.no. INDICATIONS U VALUES Required




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6.200 KVA 500 KVA 630 kVA

1 Manufacturer2 Place of manufacture3 Port of embarkation4 Manufacturer drawing reference5 Standards IEC 60076 IEC 60076 IEC 600766 Rated power kVA 200 500 6307 Cooling mode AN AN AN8 Primary rated insulation voltage kV 36 36 369 Primary operating voltage kV 33 33 3310 Secondary rated operating

voltageV 415/240 415/240 415/240

11 Rated short duration powerfrequency withstand voltage forprimary winding

kV 70 70 70

12 Rated lightning impulse withstandvoltage for primary winding

kV 170 170 170

13 Short-circuit impedance % 4 4 414 Short circuit current on secondary

sidekA 6.9 17.4 21.9

15 Voltage setting % +5.0, +2.5, 0,-0.25, -5.0

+5.0, +2.5, 0,-2.5, -5.0

+5.0, +2.5, 0,-2.5, -5.0

16 Vector Group Dyn11 Dyn1117 Maximum noise level dBA 65 dB at 1.5

metres65 dB at 1.5

metres65 dB at 1.5

metres18 Class of Insulation F F F19 Maximum iron loses W As per

Manufacturer(Efficiencyrequired isdefined in

Specifications)

As perManufacturer

(Efficiencyrequired is definedin Specifications)

As perManufacturer

(Efficiencyrequired isdefined in

Specifications)20 Maximum load loses W As per


Specifications)

As perManufacturer

(Efficiencyrequired is definedin Specifications)

As perManufacturer


Specifications)21 Dimensions (maximum)*

- Length- Width- Height

mmmmmm

7.200015002250

200020002250

22 Weight (maximum)* kg 1700 3000*Dimensions shown are indicative only

5.2 AUXILIARY TRANSFORMER 1600 KVA AND 2000 kVA

S.no. INDICATIONS U VALUES Required




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8.1000 KVA 1600 KVA 2000 KVA

1 Manufacturer2 Place of manufacture3 Port of embarkation4 Manufacturer drawing reference5 Standards IEC 60076 IEC 60076 IEC 600766 Rated power kVA 1000 1600 2000

7 Cooling mode AN AN AN7 Primary rated insulation voltage kV 36 36 368 Primary operating voltage kV 33 33 339 Secondary rated operating voltage V 415/240 415/240 415/24010 Rated short duration power

frequency withstand voltage forprimary winding

kV 70 70 70


kV 170 170 170

12 Short circuit impedance % 6.0% 6.0% 6.0%13 Short circuit current on secondary

sidekA 23.1 37.1 46

14 Voltage setting (Off load Tapchanger)

% +5.0, +2.5, 0,-0.25, -5.0

+5.0, +2.5, 0,-.2.5, -5.0

+5.0, +2.5, 0,-.2.5, -5.0

15 Vector Group Dyn11 Dyn11 Dyn1116 Maximum noise level dBA 65 dB at 1.5

metres65 dB at 1.5

metres65 dB at 1.5

metres17 Class of Insulation F F F18 Maximum iron loses W As per


Specifications)

As perManufacturer


Specifications)

As perManufacturer


Specifications)19 Maximum load loses W As per


Specifications)

As perManufacturer


Specifications)

As perManufacturer


Specifications)20 Dimensions (maximum)*

- Length- Width- Height

mmmmmm

9.200020002250

200020002250

10.200027002250

21 Weight (maximum)* kg 3600 8000 8000*Dimensions shown are indicative only




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5.3 AUXILIARY TRANSFORMER 2500/3000 kVA and 3150/4000 kVA

S.no. INDICATIONS U VALUES Required2500/3000 kVA 3150/4000 kVA

1 Manufacturer2 Place of manufacture3 Port of embarkation4 Manufacturer drawing reference5 Standards IEC 60076 IEC 60076

6 Rated power AN 2500 3150AF 3000 4000

7 Cooling mode AN ANAF AF

8 Primary rated insulation voltage kV 36 369 Primary operating voltage kV 33 3310 Secondary rated operating voltage V 415/240 415/24011 Rated short duration power frequency

withstand voltage for primary windingkV 70 70


kV 170 170

13 Short-circuit impedance % 6 714 Short circuit current on secondary side kA 58 62.615 Voltage setting (Off load Tap

changer)% +5.0, +2.5, 0,

-2.5, -5.0+5.0, +2.5, 0,

-2.5, -5.016 Vector Group Dyn11 Dyn1117 Maximum noise level dBA 65 dB at 1.5 metres 65 dB at 1.5 metres18 Class of Insulation F F19 Maximum iron loses kW As per Manufacturer

(Efficiency requiredis defined in

Specifications)

As per Manufacturer(Efficiency required

is defined inSpecifications)

20 Maximum load loses kW As per Manufacturer(Efficiency required


As per Manufacturer(Efficiency required


21 Dimensions (maximum)*- Length- Width- Height

mmmmmm

210029002250

220030002350

22 Weight (maximum)* kg 8000 8500

*Dimensions shown are indicative only




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6. TEST SHEET

6.1 AUXILIARY TRANSFORMERSAll Tests shall be performed on a completely assembled transformer including relevantaccessories supplied.All routine tests as per IEC 60076-11 are to be conducted including Partial Dischargeduring Manufacturer’s Internal test & Factory Acceptance Test on all completelyassembled transformer.

All type tests as per IEC 60076-11 shall be conducted on one transformer for each ratingand make before supply to DMRC.. All the type tests shall be conducted on each rating of the transformer separately.

Central Electricity Authority (technical standard for construction of Electrical Plants andElectric Lines) regulations 2010, has made the short circuit testing mandatory. Shortcircuit withstand test shall be conducted on one of each type , rating and make oftransformer to validate the design and quality unless such test has been conducted.Thetest shall be conducted before making any supply to DMRC.. The relevant regulations No. are 10(3)(g), 37(4)(k), 43(2)(a)(vi), which are available onCEA’s website www.cea.nic.in.

In view of above the supplier shall subject the transformer to a short circuit test as perrelevant IEC standard meeting the requirement of above mentioned regulations of CEA.

6.2 PARTIAL DISCHARGE TESTPartial Discharge Test shall be conducted on all the transformers in fully assembledcondition during the routine tests. The maximum level of Partial Discharges shall be 10pC as per IEC 60076-11 (2004) or updated as per latest IEC.

6.3 ENVIRONMENT, CLIMATE & FIRE BEHAVIOUR CLASS

To establish above classes Transformer should to be tested As per IEC 60076-11, andreports should be submitted along with the vendor approval. The dry type transformer shallbe rated for following classes – Environment Class E2, Climatic Class C1 and Fire behaviourClass F1 -

Class E2: Frequent condensation or heavy pollution or combination of both.

Class C1: The transformer is suitable for operation at ambient temperature not below –5°C but may be exposed during transport and storage to ambient temperatures down to–25°C.




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Class F1: Transformers subject to a fire hazard. Restricted flammability is required. Theemission of toxic substances and opaque smokes shall be minimised.

6.4 MEASUREMENT OF SOUND LEVEL (SPECIAL TEST) –

Measurement of Sound Level test (special tests as per IEC 60076-11) shall beconducted during Manufacturer’s Internal test & Factory Acceptance Test on alltransformer using sound pressure level technique. The testing shall be conducted on acompletely assembled transformer including relevant accessories supplied.

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