33 Kv Switch Gear Specification

7/31/2019 33 Kv Switch Gear Specification

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ELECTRICAL

SPECIFICATION33 KV SWITCHGEAR

SPECIFICATION

DOC NO.

1001041-S-E-1001-00

ROLTA INDIA LIMITED

Project Name:NPCIL TEST FACILITY

Project No:1001041

Engineering Specification (ES)Doc No. 1001041-S-E-1001-00

Revision History

Revision

Level

Revision

Date

Revision

Description

Department Head

(Approver)

This Document and all contained herein are proprietary of ROLTA INDIA LIMITED and

is subjected to confidentiality restrictions between ROTLA INDIA LIMITED and he

Recipient. Copyright Reserved.

Copyright Rolta India Limited.All Rights Reserved.

Date: Page 1 of25

Prepared By: Checked By: Approved By:


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TABLE OF CONTENTS Page No

1. SCOPE ......................................................................................................................4

2. GENERAL REQUIREMENTS........................................................................................4

2.1 Operating Conditions ................................................................................................. 4

2.2 Codes and Standards .......................................................................................... 4

2.2.1 General Standards ...................................................................................4

2.2.2 Specific Standards .......................................................................................4

3. BASIC REQUIREMENTS ..........................................................................................5

3.1 Construction.............................................................................................................5

3.1.1 Switchgear Assembly ..................................................................................5

3.1.2 Switchgear Units .........................................................................................6

3.1.3 Main Bus .....................................................................................................6

3.1.4 Earth Bus......................................................................................................7

3.2 Power Circuit Breakers ...........................................................................................8

3.2.1 Type and Characteristics..............................................................................8

3.3 Control Circuit ......................................................................................................13

3.3.1 Control Power............................................................................................13

3.3.2 Breaker Control, Indication and Alarm ........................................................13

3.4 Protection & Metering Transformers .......................................................................13

3.4.1 Current Transformers ...............................................................................13

3.4.2 Potential Transformers .............................................................................14

3.5 Relays ...................................................................................................................14

3.5.1 Protection Relays ......................................................................................14

3.5.2 Auxiliary Relays........................................................................................17 Copyright Rolta India Limited.All Rights Reserved.

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3.6 Instrument .............................................................................................................17

3.7 Fuse .......................................................................................................................... 19

3.8 Terminal Block ........................................................................................ 19

3.9 Cable Box and Gland....19

3.10 Accessories................................................................... 20

3.11 Heater............................................................................................................20

3.12 Spare Parts .......................................................................................................20

3.13 Connection and wiring...........................................................................................20

3.13.1 Power connection.......20

3.13.2 Control wiring andconnection .......................................................................................20

3.14 Nameplates ....21

3.15 Finish.....21

3.16 Field assembly.......21

3.17 Painting .....21

3.18 Tests And TestReports22

3.19 Drawings and data....23


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1. SCOPE

This Specification defines the technical requirements related to the design and

supply of the distribution switchgear, including all equipment, manufacture,

assembly, factory wiring, inspection, testing and delivery.

2. GENERAL REQUIREMENTS

2.1 Operating Conditions

The switchgear shall be suitable for installation indoor in a ventilated electrical

room.Considering Geographic, Climatic and Non-Seismic .

2.2 Codes and Standards

2.2.1 General Standards

Design, fabricate and test equipment in accordance with the latest revision ofapplicable standards of the following regulatory agencies and institutes.

International Electrotechnical Comission (IEC)

Indian Standard (IS)

International Organisation for Standardization (ISO)

Local regulatory bodies having jurisdiction over such apparatus

2.2.2 Specific Standards

In addition to the general standards listed above, the latest editions of the

following specific standards shall apply to the extent specified herein:

International Electrotechnical Commission (IEC) And Indian Standard (IS)

IS -13118. Applicable standards for busbar

IS-5 (693) Colour finish shade Exterior for Switchgear

IS-2705 Applicable standards for Current transformer

IS 3156 Applicable standards for voltage transformer


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IS: 9224, IS: 9385 Applicable standards for HRC Fuses

IS: 1248, IS: 722 Applicable standard for Meters

IS:3231 Application standard for Relays.

IEC 60044 Instrument transformers

IEC 60255 Electrical relays

IEC 60265 High-voltage switches

IEC 60269 Low voltage fuses

IEC 60282 High voltage fuses

IEC 60417 Graphical symbols for use on equipment

IEC 60446 Basic and safety principles for man-machine interface, marking

and identification - Identification of conductors by colours or

numerals

IEC 60470 High-voltage alternating current contactors and contactor-based

motor-starters

IEC 60529 Degrees of protection provided by enclosures (IP Code)

IEC 60694 Common specifications for high-voltage switchgear

IEC 60947 Low-voltage switchgear and controlgear

IEC 61000 Electromagnetic Compatibility

IEC 62271 High-voltage switchgear and controlgear

3. BASIC REQUIREMENTS

3.1 Construction

3.1.1 Switchgear Assembly

The assembly shall be made up of metal-clad switchgear units of standard

dimensions bolted together to form an enclosed, self-contained, self-supporting


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structure mounted on base channels with anchor bolt holes for installation on

concrete floor. The assembly shall be equipped with common power and groundbusses and shall be suitable for the future addition of units at each end.

3.1.2 Switchgear Units

Each unit shall be provided with:

a) Earthed metal barriers to isolate control compartments from powercompartments.

b) Separate front hinged doors to provide access to circuit breaker and auxiliarycompartments.

c) Removable rear panels, with suitable fastening devices of the captive type, to

permit access to bus work and to current transformers and cable compartments.

d) Screened louvers for ventilation and relieving of pressure caused by circuit

interruption.

e) Protective shutters to automatically close the openings to the primary

disconnects when the circuit breaker is withdrawn from its connected position.

f) Fixed guide rails for easy racking-in/out of the circuit breakers.

g) Anti-condensation, thermostatically-controlled space heater with independent

protective device.

3.1.3 Main Bus

The main bus bars shall be of high strength, high-conductivity Aluminium (D50

SWP) with non-hygroscopic, flame-retardant insulation (PVC, epoxy, etc.) bracedto withstand the maximum short circuit current of the system. Bus joints shall be

silver plated and shall utilize non-corrosive hardware. Busbars shall be ratedin accordance with the service conditions and therated continuousand short time current ratings specified in Data Sheet.Maximumtemperature of the main busbars and busbar connections, underoperating conditions, when carrying rated normal current at ratedtemperature shall not exceed 90/105 Deg. C for non-silver plated /

silver plated joints/connections. Busbar temperature limits shall beadhered to without forced cooling method. For tap off busbars,the current ratingshall be at least equal to corresponding breaker(s)rating.


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All busbar joints and bus tap joints shall be preferably be silverfaced. In case of aluminium busbars with bare joints, suitableneutral grease shall be applied to the meeting surfaces afterfinishing the surfaces to prevent oxide formation. For joints to be made

at site, sufficient quantity of grease shall be supplied by the VENDORin suitable containers.

Unless supported by impulse voltage withstand test results, phase tophase and phase to earth clearances in air of the busbars and live partsshall not be less than those specified in Data Sheet.

Busbars shall be adequately supported on insulators, to withstanddynamic stresses due to short circuit current specified in Data Sheet.Busbar support insulators shall conform to relevant standards specifiedin Data Sheet.

Main busbars shall be located in air insulated enclosures and segregated

from all other compartments of the cubicle. Direct access or accidentalcontact with busbars and primary connections shall not be possible. Toprovide a seal between adjacent cubicles, busbars shall be taken through seal-off bushing or insulating blocks.

Busbars and Sleeves

The busbars when sleeved shall be with flame retardant heat/coldshrinkable sleeve. All joints shall be provided with removable shrouds. Thebusbar sleeves, shrouds material shall be suitable for continuous operatingtemperature of 5 Deg. C higher than the maximum permissible operating

temperature of busbars / joints.The sleeving material shall not crack, peel orloosen on the busbars when subjected to thermal cycling during service andshall be of such quality as not to require replacement for life of switchgear. It

shall be possible to remove and refix the shrouds repeatedly withoutdamaging them. Test certificates pertaining to the quality of the sleevingmaterial and shrouds shall be

submitted by Bidder.

3.1.4 Earth Bus

An earthing bus shall be provided and extended throughout the lengthof the switchgear. It shall be bolted to the framework of each unit andbrazed to each breaker earthing contact bar.The earth bus shall havesufficient cross section to carry the momentary short circuit and short timefault current for at least (1) second or higher as specified in Data Sheet,without exceeding maximum allowable temperature rise causing damage tothe switchgear.Suitable clamp type terminals at each end of the earth bus


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shall be provided to suit the size of the PURCHASERS earthingconductors.Bolted joints, slices, taps etc. to the earth bus shall be madewith at least two bolts.Positive earthing of circuit breaker frame shall bemaintained when it is in the connected position and in all other positions

whilst the auxiliary circuits are not totally disconnected.Hinged doorsshall be earthed through flexible earthing braid of adequate cross section. Allnon-current carrying metal work of the switchgear shall be effectivelybonded to the earth bus.

A continuous earth bus of high-strength, high-conductivity copper of size 50 X 6.mm shall

be provided the length of the assembly and solidly bolted to the steel framework. It shall becapable to carry the rated short circuit current of any breaker in the assembly for a period of

one second without exceeding maximum withstanding temperature .

3.2 Power Circuit Breakers

3.2.1 Type and Characteristics

The circuit breaker shall be 3-pole, single throw, vacuum , draw-out type with self-aligning

primary and secondary disconnecting devices. The breaker shall be mechanically and

electrically trip-free equipped with stored energy closing and antipump operationmechanisms and suitable for 110V DC (-15 to +10%) closing and trip. The circuit breakers

shall be operated from the cubicles front.

Each circuit breaker shall have three, clearly-marked definite positions within its

enclosure, i.e. "service", "test" and "fully withdrawn" positions. Mechanical interlocks

shall be provided to prevent inserting or withdrawing a closed breaker and also toprevent closing the breaker unless it is in the "service" or "test" positions.

CIRCUIT BREAKERS, VACUUM CONTACTORS & DISCONNECTORS:

Circuit breakers shall be one of the following types and selection shall beas specified in Data Sheet.a) Sulphur Hexafluoride Breaker (SF6)b) Vacuum Circuit Breaker (VCB)

These shall conform to relevant standards specified in Data Sheet andshall be of the horizontal draw-out type. Circuit breakers shall comprisethree separate identical single pole units operated through a commoninsulated shaft by the operating mechanism. Breakers of identical ratingsshall be fully interchangeable without any adjustment.Circuit Breaker withforced air-cooling for increasing its rating will not

be acceptable. insulated shaft by the operating mechanism. Breakers ofidentical ratings


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shall be fully interchangeable without any adjustment.Circuit Breakerwith forced air- cooling for increasing its rating will not be acceptable.

Circuit Breaker Duty.

Circuit breakers shall be suitable for switching duty of transformerwhose maximum capacity is furnished in Data Sheet and other devicesspecified in Data Sheet. adequate provision shall be made on circuitbreakers for motor switching to limit the over voltage to 2.2 p.u. rated peakline to earth voltage (1.0 microsec. to crest).Closing and Opening operationtime difference shall be limited to 2 cycles (40 ms) to facilitate fast bustransfer operation.The breakers controlling motors shall be provided with

suitable devices to operate satisfactorily under the following conditions :a) Direct-on-line starting of motor whose maximum capacity and

starting time are furnished in Data Sheet.

b) The frequency of motor starting can be either one start from hotcondition or two successive starts from cold condition or three equallyspaced starts in an hour from hot condition.

c) Suitable shunt resistors or surge arrestors, if necessary shall beprovided to restrict the voltage peaks during switching off motor, to 2.2 p.u.of rated peak line to earth voltage.

Circuit breaker along with its operating mechanism shall be mounted ona wheeled carriage moving on guides, designed to align correctly and alloweasy movement. Plugs and sockets for power circuits shall be silver faced andshall be insulated with suitable insulating material shrouds.

There shall be Service, Test Fully withdrawn positions for the

breakers. In the Test position the circuit breaker shall be capable of beingtested for operation without energising the power circuits, i.e. the controlcircuits shall remain undisturbed while the power contacts shall remaindisconnected. Separate limit switches, each having a minimum of 2 NO + 2NC contacts, shall be provided for both Service and Test

positions of the circuit breakers for Purchasers use. These contacts shallbe rated for 10 amps, 240 V AC and 0.5 amp (inductive breaking) at 220VDC.

Auxiliary Connection / Contacts :

Connection of the control/interlocking circuits between the fixed portionof the cubicle and the breaker carriage shall be preferably by means ofplug socket arrangement.Self aligning disconnects shall have adequatenumber of contacts to meet the requirements of control and interlockingscheme. Contact between the fixed and moving parts of the disconnects shallbe established to enable testing of breaker outside panel.Plug and socket

arrangement when provided, shall have adequate number of pins tomeet the requirements of control and interlocking scheme with a minimum


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of 24 pins. The plug and socket arrangement shall be so designed that itshall be possible to insert the plug in the socket in one position only. Theplug, after insertion, shall be secured in position by spring clamps, whichneed considerable force to operate. The length of the plug chord will be such

that the plug can be inserted into the socket only when the breaker is pushedinto the test position. Suitable interlock will be provided to permitfurther pushing of the breaker only if the plug is inserted correctly into thesocket. It shall not be possible to remove the plug when the breaker is inservice position and it shall be necessary to withdraw the plug from thesocket before the breaker can be pulled out from the test position to fullywithdrawn position. When a service isolating switch is furnished as an

integral part of the circuit breaker, the operation of the Disconnectorshall be co-ordinated

with that of the circuit breaker to ensure that it opens after the powerbreak and is not required to interrupt the load current. Service Disconnectors

however, may be allowed to interrupt the residual current through quenchingor damping resistors incorporated in the circuit breakers.

SF6 BREAKERS

SF6 breakers shall be of puffer type or self extinguishing type withrotating arc of dead tank and single pressure design. The movement ofpiston attached to moving linkage mechanism shall be designed in such away that the build-up of dielectric strength inside the chamber isproportional to the current to be interrupted in order to avoid prolonged

arcing in the event of short circuit and current chopping in the event.

low load currents. SF6 pressure/density monitoring switch/contacts shallbe provided.

Materials such as activated alumina or molecular sieve shall be providedat appropriate locations to absorb products of decomposition of SF6 gasand for moisture absorption. Under no operating conditions, the moisturecontent in the SF6 gas shall be allowed to exceed 15 ppm. The second stagedensity switches provided shall be as follows :

a) Under pressure - I STAGELow pressure alarm and locking out of the closing circuit shall be

incorporated.

b) Under pressure - II STAGEThis pressure shall be above the safe lowest operating pressure for the

breaker as guaranteed and tested by the manufacturer. Breaker shall betripped with annunciation.

5.9 Vacuum breakers shall have completely sealed interrupting units forinterruption of arc inside the vacuum. The breakers shall be provided withcontact wear indicator visible from the front of the equipment, withoutrequiring opening of the cubicle door, allowing the operator to assess the


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conditions of the interrupters whilst the unit is in service. It shall bepossible to isolate easily the vacuum interrupter unit from the operatingmechanism for mechanical testing of the interrupter to check loss of vacuum.

The vacuum breakers shall be complete with surge arrestors to provide

protection to the equipment against switching surges.

DISCONNECTOR / SWITCH DISCONNECTOR / FUSE UNIT:

Unless otherwise stated Data Sheet, Disconnectors shall be of the off-load and drawout type. On load Disconnectors (load break switches)shall be provided in place of breakers and be complete with suitably sized

HRC or expulsion type fuses, as specified. Short time rating of theDisconnector shall be same as that of the associated breakers. Disconnectorshall be capable of making and breaking capacitive current of associated

equipment such as busbars, cable(s) and transformer(s). Position indicatingRed and Green lamps shall be provided on theDisconnector cubicles. Inaddition, contacts shall be wired upto terminal blocks for connectinglamps for remote indication of Disconnector position.Mechanical andelectrical interlocks shall be provided where applicable to ensure that theDisconnectors cannot be operated unless the associated breakers are

open.Disconnectors shall be provided with suitably designed motor driveif specified in Data Sheet. Motor drive shall be complete with suitably

rated starter including fused disconnects.

VACUUM CONTACTORSThe vacuum contactors shall be in medium voltage operation range of

1.5--7.0 kV. The fixed contact shall be brazed to the lower end plate and themoving contact shall be guided by self lubricating bearings. Bellows shallbe provided to allow free contact movement. The bellows shall be brazed tothe copper end plate and to the bottom of the moving contact system. Theend plates shall be jointed and insulated by a tubular glass section, thecomplete assembly forming the contactor enclosure. Aspatter shield shall

collect any spray arcing material and prevent a

tracking path from accumulating on the inside of glassenvelope.Evacuation of the contactor shall be achieved through diffusionpumping while the contactor is being baked. The contactor shall then besubjected to d.c. arcing, to condition and out-gas the component materialsand to achieve a vacuum of better than 10-3Torr. The contact faces shallbe machined to provide center and annular reservoirs, which shall be filledwith a suitable alloy.The vacuum contactors shall be either ofmechanically latched or electrically held type. The electrically held


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contactor shall be just like a low voltage contactor.In applications whereswitching frequency is very low, mechanically latching device shall beprovided and armature shall be held in close position by means of a

mechanical device during working and detached by means of a shut trip

coil, as specified.

CIRCUIT BREAKER OPERATING MECHANISM

Circuit breaker shall be power operated by a motor charged springoperated mechanism. It shall be strong, rigid, positive and fast in operationto ensure that

a) Main poles of the breakers shall be such that unless otherwisespecified, the maximum difference between instants of contactstouching during closing shall not exceed half cycle of rated frequency.

b) Main poles of the breakers shall operate simultaneously. There shallbe no objectionable rebound of moving contacts and the mechanismshall not require any critical adjustment.

Operating mechanism shall be non-pumping electrically andmechanically under every method of closing (except during manualclosing of a breaker for maintenance). Electrical antipumping feature shallbe obtained by means of an auxiliary relay and use of a contactor to achievethis feature shall not be acceptable.

Mechanism shall be such that failure of any auxiliary spring shall notprevent tripping and will not cause tripping or closing operation of the poweroperated closing devices. When the circuit breaker is already closed,

failure of any auxiliary spring shall not cause damage to the circuitbreaker or endanger the operator.The closing release shall operate

correctly at all values of voltage between 85% and 110% of the ratedvoltage. A shunt trip shall operate correctly under all operating conditions ofthe circuit breaker upto the rated breaking capacity of the circuit breakerand all values of supply voltage between 70% and 110% of rated voltage.

Working parts of the mechanism shall be of corrosion resistantmaterial.Bearings which require grease shall be equipped with pressuretype grease fittings. Bearing pin, bolts, nuts and other parts shall beadequately pinned and locked to prevent loosening or changing adjustmentwith

repeated operation of the breaker.Auxiliary switches mounted on thefixed portion of the cubicles and directly operated from the breakeroperating mechanism on each breaker having 6 NO and 6 NC potential-free contacts rated for 10 amp, 240V AC and 0.5 amp (inductivebreaking) 220V DC shall be provided.


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contacts shall be in addition to those utilised in the control circuit ofeach breaker and shall be exclusively meant for the PURCHASERS use inexternal interlocks and controls.

SPRING OPERATED MECHANISM

Spring operated mechanism, shall be complete with motor of adequaterating, opening spring, closing spring with limit switch for automaticcharging and all necessary accessories to make the mechanism a completeoperating unit.

As long as power is available to the motor, a continuous sequence ofclosing and opening operations shall be possible. After failure of powersupply to the motor, at least one open- close-open operation of the circuitbreaker shall be possible.

Breaker operation shall be independent of the motor which shall be usedsolely for charging the closing spring.Closing action of the circuit breaker shall compress the opening spring

ready for tripping.When closing springs are discharged, after closing a breaker, closing

springs shall automatically be charged for the next operation.Motor shall be such that it requires only about 30 sec. for fully charging

the closing spring. Motors shall be rated for 220 V DC and/or 240 V AC and/or110V DC as specified in Data Sheet and shall operate satisfactorily at allvalues of voltage between 85% to 110% of rated voltage. Motor shall beprotected against overloads and stalling. Mechanical indicators to indicate

charged and discharged condition of spring shall be provided. Alternatemeans must be provided to charge the closing springs manually. Necessaryhandles shall be supplied with Circuit Breakers.

OPERATING MECHANISM CONTROL :

Operating mechanism shall normally be operated by remote electricalcontrol when the breaker is in Service or Test position. Electrical trippingshall be performed by shunt trip coils. Provision shall also be made for localelectrical control when the breaker is in Test position by a control switchon the switchgear cubicle door. Also, Local/Remote

selector switch lockable in Local position shall be provided on thecubicle door. `Red and `Green indicating lamps shall be provided oncubicle door to indicate breaker close and open positions. BreakerService and Test positions shall be indicated by separate indicatinglamps on the cubicle door, in case mechanical indication of Service and

Test positions are not available on the cubicle door.


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3.3 Control Circuit

3.3.1 Control Power

Control power for breaker closing and tripping circuits shall be 110VDC (unless

otherwise indicated) from a source external to the switchgear.

3.3.2 Breaker Control, Indication and Alarm

Breaker control switch shall be heavy duty, rotary type with pistol grip handle,

two-position "close-trip" spring return with target to indicate the last operation.

Minimum indication requirements per breaker are as follows:

Trip voltage available

Test and Service position indication.

All alarms, pre-warnings, etc., to be gathered in one common signal for remote

indication.

Transformer gas and temperature signals will be hard wired from transformer to

transformer feeder cubicles.

3.4 Protection & Metering Transformers

Current Transformers (For metering)

One set of three (3) C.T. per incomer and feeder with 1A secondary shall be provided formetering and wired through current test blocks for incomers and tie breakers and for feeder

breakers.

The transformers shall be of the dry type insulated for the full voltage rating of theswitchgear and shall have their thermal and mechanical rating capable of

withstanding the short circuit rating of the associated circuit breaker.

The transformers shall have their accuracy established in accordance with the

connected burden and IS 2705. Current transformers for metering applicationsshall have Class 1 accuracy or better. In specialcases where low CT turns ratioand high burden requirements arespecified, the accuracy class of CTshall be 3.0. With these CTs theoverall error shall be limited to 4.5%


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with an accuracy class 1.5 forindicating instruments. When auxiliary CTsare used the overall error ofthe combination shall be restricted to 1%.

CTs shall have the following burdens unless otherwise specified.

Motor & other feeders - 10 VA

Instrument security factor shall be less than 5 unless otherwisespecified.

Current Transformers (For Protection)

Protection CTs shall have class of accuracy of 5P20 and minimumburden

10 VA unless otherwise specified. Core balance CTs shall be such thatthe earth fault relay should be able to operate over its entire range.

3.4.2 Potential Transformers

One (1) set of two (2) potential transformers per incomer, connected in open delta,

With 110/3 volt secondary shall be provided for metering and protection for each bussection.

The transformers shall be of the draw-out type protected by HRC fuses ontheir primary and secondary and shall be designed to withstand the basic impulse

level of the switchgear and with interrupting ratings corresponding to breakerrating in accordance with IS 3156. It shall be possible to replace the secondary

fuses safely when the switchgear is energised. Precautions shall bemade such that the primary fuses can behandled only in the de-energised position. Drawout contacts for Phase

and Neutral terminals shall be identical. Alternatively, MCB havingauxiliary contact shall be provided.

3.5 Relays

3.5.1 Protection Relays

The relays shall be square or rectangular in shape and shall have dusttight, transparent covers removable from the front.

Relay cases shall be suitable for flush mounting with only flangesprojecting on the front with connections from the rear.

Relay cases shall have adequate number of terminals for makingpotential free connections to the relay coils and contacts including spare


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contacts.Relay case size shall be so chosen as not to introduce any limitationson the use of available contacts of the relay due to inadequate number ofterminals.

Provision shall be made for easy isolation of trip circuits of each relay forthe purpose of testing and maintenance.

Relay Contacts / Output:

Relays when specified or required in specific application shall haveelectrically independent output contacts for the following purposes:

a) Tripping circuit.b) Remote/local annunciation.c) Data Acquisition System.d) Spare (for event recorder, etc.)

If the main relay does not have sufficient number of output contactsinherently, these shall be multiplied using auxiliary relays, to be covered inthe Vendors scope of supply. Relay contacts shall be silver faced with springaction. Output elements of all static relays shall consist of electro-mechanical relays only.

Except as noted otherwise in Data Sheet-A, all AC relays shall besuitable for operation on 50 Hz. Voltage operated relays shall be suitable for110V AC and current operated relays for 5 amps or 1 amp. CT secondary,as specified in Data Sheet-A1. Auxiliary relays and timers shall be suitable

for specified voltage and operate satisfactorily between 80% and 110% ofrated voltage. Voltage operated relays shall have adequate thermal

capacity for continuous operation.

Auxiliary seal-in units provided on the protective relays shall bepreferably of shunt reinforcement type. If series relays are used thefollowing shall be strictly ensured:

a) The operating time of the series seal-in unit shall be sufficientlyshorter than the trip coil in series with which it operates to ensuredefinite operation of the flag indicator.

b)Seal-in unit shall obtain adequate current for operation when one ormore relays operate simultaneously.

c) Impedance of the seal-in unit shall be small enough to permitsatisfactory operation of the trip coils when the DC supply voltage isminimum (i.e. 70% of rated value).


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d) Series seal-in units shall have two taps, one rated for 0.2 amps andthe other rated for 2.0 amps.

The protective relays shall conform to following requirements:

All the relays shall be wired in such a way that power supply failure tothe relay does not cause maloperation of another relay.

Unless otherwise specified in Data Sheet-A1, type of relays either staticor electro- mechanical which meet the various performance requirementsstipulated herein are considered acceptable.

The protective relays shall have high degree of reliability, low powerconsumption and plug-in or draw-out type, of modular assembly to facilitatemaintenance. The modularisation shall be provided as per therecommendations of relevant specifications.

The relays shall be equipped with either hand reset type mechanicallyoperated operation indicator or LEDS for visual indication. The LED lampsshall be resettable by a push button located in an easily accessible place onrelay case. On 3-phase relays with separate operation indicator for eachphase, the indicator shall be clearly marked with the reference phase. Eachoperation indicator shall have its function and the principle of

operation in a symbol inscribed clearly.

Protective relays shall be suitable for secondary rating of CTs and whendrawn out should short CT secondary which should not even momentarily getopen circuited.

Protection relays shall be electronic (3 years minimum of power service) and shallwithstand surge test in accordance with the applicable IEC standards.

Relays shall be provided as per the data sheet. As a minimum the followingprotective functions shall be provided:

Incomers: ANSI 27,98,59, 50/51, 50N / 51N.

Feeders: ANSI 98,27, 50/51, 50N/51N

Bus Tie: ANSI 50/51, 50N/51N.

Tripping Relays:

The tripping relays shall be latch-in type with hand reset facility andshall


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preferably have operating time not exceeding 20 ms. Each tripping relayshall have adequate number of normally open (NO) and normally closed (NC)heavy duty contacts as specified either in Section-C or Data Sheet-A.Barriers shall be provided between each set of contacts. If sufficient contacts

are not available on each tripping relay, moretripping relays may be used. The tripping relays shall be preferably ofhand reset type. If electrical reset type of relays are used, a push buttonshall be provided on the panel

for resetting the relay.

All tripping relays used shall be so connected that supervision of eachrelay is possible. For facilitating supervision of these tripping relays, highburden tripping relays shall be provided. Supervision relays having threeoutput contacts for annunciation, DAS and event recorder wherespecified, shall be provided for supervision of each tripping relay.

3.5.2 Auxiliary Relays

Auxiliary relays(4 NO + 4 NC) shall be switchgear type with coil and heavy duty contactsrated for operation on 110V DC.

3.6 Instruments:

Indicating Instrument:Unless otherwise specified, all electrical indicating instruments

shall be 96 mm square, with 240 degrees scale. They shall be suitable forflush mounting on vertical panels and inclined faces of desks whoseinclination from horizontal or vertical shall not exceed 20o.

Instrument dials shall be white with black numerals and lettering.Knife edge pointers and parallax free dials shall be preferred. Instrumentsshall be provided with non-reflecting glass.

Instruments shall have accuracy class of 1.5 or better. The designof the scales shall be such that it can read to a resolution correspondingto 50% of the accuracy class index.

Ammeters and Current Coils of Wattmeters and VARmeters shallcontinuously withstand 120% of rated current and 10 times the ratedcurrent for 0.5 secs. without loss of accuracy. Voltmeters and PotentialCoils of wattmeters and VARmeters shall withstand 120% of rated voltagecontinuously and twice the rated voltage for 0.5 secs without loss ofaccuracy.


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Ammeters for motor feeders shall have compressed extended scale toread upto six to nine times the rated current of the motor.

Metering Instrument:

Meters shall be electronic type meters that collect, process and storeelectrical parameters, energy use and demand data on a timeof the day or demand basis. Meters shall measure all electricalparameters like Voltage,Current, Watt, Watt- hrs, Var, Var-hrsand Power factor in all phases.Meters shall preferably be of accuracy class0.5.

Watt-hour and Varhour measurement shall be suitable for unbalancedloads in three phase three wire circuits. They shall be suitable forflushmounting or semiflush mounting on vertical panels with only flanges

projecting outside with back connected terminals.

The meters shall be suitable for operation from the secondary of CTsandVTs. They shall be provided with a separate test block for the testingof the meters without disturbing the CT and PT secondary connections.

Meters shall provide enhanced LCD display which, shall include but notlimited to (a) Six digits display of metered quantities and constants (b)Potential indication for each phase. The display can be programmed to scrollthrough the sequence of programmed display items in any sequence.

Meter shall have non-volatile memory such that in the event of linevoltage interruption, the meter circuit immediately transits to a mode oforderly shut down and data gets preserved. When power is restored datacollection resumes.

Meters shall be equipped with communications interface with MODBUSorany other open type of protocol, which permits meters to be read orreprogrammed from remote locations.

Maximum demand (MD) indicators if specified, shall process all the threedemands kW/kVAR/kVA simultaneously. Demand intervals shall be

programmable from 1 minute to 60 minutes in step of one minute. The MDcomputation may be on block interval / rolling time basis. In addition,demand quantities may be displayed on cumulative/continuous cumulative

basis. MD indicators can be reset with the Reset push button or can beprogrammed to reset automatically at periodic intervals.

Meters shall have tamper detection facility. Meters shall detect anypossible form of tamper like PT removal/CT reversal etc & shall store


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date/time of tamper and restoration in the meter. Further, it shall haveprovision of seals. Meter shall also have a feature for working satisfactorily inabsence of neutral.

Electro mechanical types of meters are also acceptable and its typeshall be subject to approval.

Recording Instrument:

Recording instruments shall be rectangular in shape and shall besuitable for semi-flush mounting on panels with only flanges projecting. Theyshall be of drawout type for chart replacement and suitable for backconnection. Provision shall be made for automatic shorting of CTleads,when the recorder is drawout.

Watt and VAR recorders shall be suitable for recording of unbalancedloads in 3 phase 3 wire circuits. The equipment shall consist of Watt &VAR transmitters (transducers) of output range 0-5 mA, accuracy class 0.5,suitable for the input quantities from specified CTs & VTs. The Watt

& VAR transmitters shall be either separately mounted or integral withthe recorder and they may be used to feed the summating indicatorWatt/VAR meter.

3.7 Fuses

Fuses generally shall be of the HRC cartridge fuse- link type having adequate rupturingcapacity.

3.8 Terminal Block

Terminal blocks shall be colour coded 650 V grade, 10 Amps rated, onepiece moulded, complete with insulated barriers, stud type terminals,washers nuts and lock nuts and identification strips. Markings on theterminal strips shall correspond to wire numbers on the wiring diagrams.Terminal blocks for CT and PT secondary leads shall be provided with testlinks and isolating facilities. Also CT secondary leads shall be provided with

short circuiting and earthing facilities. Not more than one wire shall beterminated on either side of a terminal.When it is required to terminate twoor more wires on the same terminal, the wires shall be terminated onadjacent terminals and these terminals shall be shorted using suitableshorting links.At least 10% spare terminals shall be provided on each paneland these spare terminals shall be uniformly distributed on all terminal blocks.


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This shall include 10% spare terminals for inter cubicle wiring also. Allspare contacts and terminals of the panel mounted equipment and devicesshall be wired to terminal blocks.Protective covers of transparent plasticfor placing over live parts of the terminal blocks shall be provided.Unless

otherwise specified, terminal blocks shall be suitable for connecting thefollowing conductors of the PURCHASERS cables on each side :a) All circuits except CT : Minimum of two 2.5 mm2 circuits copperb) CT circuits : Minimum of four 2.5 mm2 copperThere shall be a minimum clearance of 250 mm between the first row of

terminal blocks and the associated cable gland plate. Also the clearancebetween two rows of terminal blocks shall be a minimum of 150 mm. Mouldingterminals shall be self extinguishing or resistant to flame propogations,substantially non-hygroscopic and shall not carbonise when tested fortracking. The insulation between any terminal & framework or between

adjacent terminals shall withstand a test of 2 kV for one minute.

The mouldings shall be mechanically robust to withstand handling whilemaking terminations.Suitable barriers shall be provided between twoterminals connected to different voltage supplies.

3.9 Cable Box and Gland:

Cable boxes/pot heads and glands shall be provided in the switchgear, ifcalled for in Data Sheet Cable boxes/pot heads for power cables shall besuitable for stranded aluminium or copper conductor, PVC insulated cablesor cross-linked polyethelene insulated cables, as specified in Data

Sheet.Cable terminating boxes along with termination kits shall be suppliedcomplete with all accessories (including epoxy resin compound) required forterminating PURCHASERS cables shall be furnished by the VENDOR. Theaccessories shall include but not be limited to compound, tapes, binding wires,filters, armour clamps, brass gland etc.Connecting leads of adequate size with

terminal clamps for connecting cable box terminals to switchgearequipment terminals shall be included. Cable box shall withstand the shortcircuit rating of the switchgear.

Necessary number of cable glands shall be provided for terminatingauxiliary power and control cables.Glands shall be of heavy duty brasscastings, machine finished and complete with check nut, washers,

neoprene compression ring etc.Whenever core balance C.T. is mountedoutside the panel, sufficiently long pigtail shall be provided to enable the

pig tail to be threaded through the core balance C.T. before connectingto earth.

3.10 Accessories:

Suitably rated MCB(s) shall be used for protection of auxiliary supplies.


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3.11 Heater:

Each switchgear cubicle shall be equipped with heaters to prevent

moisture condensation within the enclosure and shall be complete with switchfuse unit for power supply. Heaters and switch fuse units shall be suitablefor continuous operation on 240V, 1 phase, 50 Hz AC supply.Plug Point A240V, 1 phase, 50 Hz. AC plug point shall be provided in the interior ofeach cubicle with an on-off switch for connection of hand lamps.Interior

Illumination.Metering/wiring cubicle shall be provided with CFL fitting forillumination.

3.12 Spare Parts:A list of spares is provided in the Data Sheet. Whether included in theVENDORsrecommendations or not, unit prices of all the items in this list

shall be quoted together with their suggested quantities for three (3) yearssatisfactory operation along with the catalogue numbers.

3.13 Connections and Wiring

3.13.1 Power Connections

The switchgear shall be provided with the following items for power connections:

a) Compression-type lugs and supports for the incoming and outgoing cables.

b) Sufficient space for stress cones.

c) Removable plate (non-magnetic for single conductor) where cable entry is from

the top of the switchgear.

3.13.2 Control Wiring and Connections

Control wiring shall be 2.5 sqmm minimum, single conductor stranded copper(5/7 cores) having 1.1KV flame-retardant insulation. Connections to the Owners external

circuits shall be brought to pressure type terminal blocks with marking strips.

3.14 Nameplates

The following nameplates shall be provided:

a) Rating nameplate for each switchgear unit showing as a minimum: Tag No.,

rated voltage, rated current, interrupting current, frequency, manufacturer's Copyright Rolta India Limited.All Rights Reserved.

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shop reference and drawing number.

b) Circuit identification nameplate on front of each cell.

c) Device identification nameplates for instruments, meters, relays, fuses etc.

d) Main identification nameplate for the switchgear assembly.

e) High voltage warning nameplate for the switchgear assembly.

3.15 Finish

Metal surfaces shall be cleaned, given rust-inhibiting treatment, primed and painted with

a minimum of two coats of finish paint. Paint finish color shall be BS 4800 Grey shade

10A3.

3.16 Field Assembly

Equipment shall be shipped completely assembled whenever feasible. When equipmentmust be shipped in sections, materials and instructions for field assembly shall be

provided. Terminal strips and wiring diagrams shall be provided to facilitate reconnection

of wiring at the shipping splits with each wire and terminal identified with permanentmarkers.

3.17 Painting

Rust and scale shall be removed by pickling with dilute acid followed bywashing with running water, rinsing with slightly alkaline hot water anddrying. Oil, grease, dirt and swarf shall be thoroughly removed by emulsioncleaning. All sheet steelwork shall be phosphated in accordance with thestandard procedures (seven-tank process) and conforming to relevantstandard for phosphating iron and steel. After phosphating, thorough rinsingshall be carried out with clean water, followed by final rinsing with dilutedichromate solution and oven drying.The phosphate coating shall be sealed bythe application of two coats of ready mixed, stoving type primer. The firstcoat may be flash driedwhile the second coat shall be stoved. Afterapplication of the primer, two coats of finishing paint shall be applied, withfirst coat of paint followed by stoving. The type of paint and paint shadeshall be as specified in Data Sheet. Manufacturerrecommendations onuse of suitable primer and painting procedure shall be adhered to. Each coatof primer and finishing paint shall be of a slightly different shade to enableinspection of the painting.The final finished thickness of paint film on steel


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shall not be less than 100 microns, and shall not be more than 150microns. For painting by electrostatic process the minimum thickness canbe 50 microns.Vendor can offer powder coating method as an alternativeto the above but this technique shall be fully detailed for approval.Finished

painted appearance of equipment shall present an aesthetically pleasingappearance, free from dents and uneven surfaces. If better painting standardis offered the same shall be clearly elaborated in detail. Material notcomplying with the foregoing requirements are liable to be rejected.

3.18 Tests And Test Reports:

All meters and other reference devices used for testing shall have validcalibration Certificate traceable to reputed national

laboratories/institutes.Inspection by Purchaser/Engineer will not be carried outunless the vendor confirms that such calibrated equipment are ready forproceeding with the tests.Instruments and gauges to be used for testing andinspection of critical

parameters as identified in the specification shall have valid calibrationand the accuracy traced to national standards.The VENDOR shall completelyassemble, install all the associated equipment including brought out itemsmounted and wired and test eachcubicle as per relevant standards specifiedin Data Sheet.

Routine tests shall be carried out on completely assembled equipment

as per relevant standards specified in Data Sheet.Functional tests shall becarried out to demonstrate the specified control and interlocks.Copies ofthe test certificates for all brought out items shall be submitted for thePURCHASERS approval before despatch of the switchgear.Bound copies ofcomplete test results as specified in the distribution schedule shall befurnished with the switchgear. These shall include complete reports andresults of the routine tests as also certified copies of type tests carried outon equipment of identical design.Oscillographic test records for closingand tripping timings of the breakers

shall also be furnished.The VENDOR shall indicate the manufacturersstandard routine tests for vacuum contactors. The VENDOR shall completely

assemble and test each vacuum contactor to ensure satisfactoryworking of all component parts and also assembled contactor and submittest certificates.

BIDDER shall furnish copies of all type test reports required as per therelevant standards. If required by the PURCHASER/CONSULTANT, any ofthese type tests shall be conducted by the VENDOR at unit rates for each of


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the type tests to be furnished in the PRICE SCHEDULE by the BIDDER.Without the type test reports, the BID shall be considered incomplete.

3.19 Drawings and data:

As part of the proposal, the VENDOR shall furnish relevant descriptiveand illustrative literature on breakers and associated equipment and thefollowing for preliminary study.

a) Complete assembly drawings of the switchgear showing plan,elevation and typical section views and locations of cable boxes/pot heads,busbar chamber, metering and relay compartment and terminal blocksfor external wiring connections.

b) Typical and recommended schematic diagrams for control and

supervision of circuit breakers.

c) Foundation plan showing location of foundation channels, anchor boltsand anchors, floor plans and openings for cables etc.

d) Type test certificates along with oscillograms for breakers of identicaldesign.

e) All drawings and data shall be annotated in English.

NOTE : Relevant standard control schematic diagrams are enclosed forbidders

guidance in estimation of Scope of work involved as regards provision of

equipment / devices / wiring etc.

Copyright Rolta India Limited. Date: Page 25 of25

Documents

33 Kv Switch Gear Specification