7 RMU

7/30/2019 7 RMU

1/16

UGVCL-Specifications RMU

Seal & Signature of Bidder Page 1

4.0 SF6 INSULATED RING MAIN UNITWITH VACUUM CIRCUIT BREAKER

SYSTEM RATED VOLTAGE UP TO 12 kV

7/30/2019 7 RMU

2/16

Seal & Signature of BidderPage 2

DESCRIPTION OF THE SWITCHGEAR.

The switchgear is termed as Metal enclosed, gas insulated ring main unit.The performed type tests and arc fault tests must be proved by documents ofindependent and selected test facilities/centers or test houses. KEMA. CESI,etc.

The Ring Main Unit should be prefabricated, filled with SF6 gas & should betested in accordance to IEC 60298 or DIN VDE 0607, part 6 or equivalent/newstandards. It should be ready for operation on delivery.

The offered switchgear must have the following features:1. Compact construction2. High staff safety and sure control3. Maximum reliability4. Maintenance free.5. Possibility of Various cable connections.

SF6 GAS TANK AND PRESSURE RELIEF.

All live parts like switching devices, busbars and related connections must beaccommodated in a common container made of STAINLESS STEEL,not lessthan 2 mm thick.Gas tank made of any other material (eg, epoxy, Mild Steel, etc) are notacceptable.The tank should be completely TIG welded, due to its higher weld quality soas to ensure IP67 degree of Protection.This should be tested in the factory for a leak rate of 0.1% per year.The Bidders should have the assembly, welding and testing facility for manufacturing RMUs in India and have to provide the documentaryevidence for the same. The bidders have a vast service facility in the country.

The container must be equipped with a suitable pressure relief device. Thepressure relief must ensure that the escaping gases are dissipated downwardsand to the rear of the equipment.

OUTDOOR INSTALATIONS

For outdoor installations the whole switchgear (RMU) should be enclosed in anMS enclosure, suitable for outdoor conditions. The same should be tested for IP54.

EXTENSIBLITY

The whole switchgear (RMU) should be suitable for extension on both thesides, with separate bushings for left and right extensibility, located on boththe sides on the upper part of the tank.

7/30/2019 7 RMU

3/16


Extensible bus-bar bushings on the roof or rear or bottom are not acceptableas they increase the dimensions of the switchgear during extension.The extensible Busbars should be Plug-in/push-on type to facilitate easy andfast connection and installation.Bolted type extensible busbars are not acceptable.They should be designed in such a way that after connection the Busbars arenot visible / exposed to the atmosphere.The gap between the RMU on connected after the extension should not bemore than 10mm.

Addition of Interconnecting BUSBARS should not exceed the dimension of thecomplete switchgear.

SWITCHING DEVICES

Every switching device must have its own drive. The plug-in holes or the holesfor drive access must be included in the interrogator interlocking system of theswitchgear.

LOAD BREAK SWITCH

The load break switches have to be designed according to IEC 60265 or DINVDE 0670 part3.The direction of rotation must be clockwise when switching ON the load break switch and counterclockwise when switching OFF the load break switch.

EARTHING SWITCH

Each switching device should be equipped with an inbuilt integrated earthingswitch.The earthing switch must be designed accordance to IEC 60129 or DIN VDE0670 part 2.The earthing switch with making capacity must be integrated in acomprehensive interrogator interlocking system and must be equipped withan ON snap action drive.The direction of rotation must be clockwise when switching ON andcounterclockwise when switching OFF the earthing switch.

MECHANISMS

The switching devices must be equipped with manual mechanisms which aresituated at the front in a separate metal-enclosed space outside the gas-filledswitching compartment.

The load break switches and earthing switches must be fitted with snap actiondrives/mechanisms.

7/30/2019 7 RMU

4/16


The drives / mechanisms for vacuum circuit breaker should be fitted with thestored energy release for tripping.

CIRCUIT BREAKER ASSEMBLY

The arc interruption in circuit breaker should be achieved in vacuum, throughvacuum interrupters.SF6 breakers are not acceptable as the no of operations on fault is very less ascompared to the vacuum breakers. Additionally the bi-products producedduring the fault interruption also effect the insulation level of SF6, henceaffecting the life of the complete RMU.The complete circuit breaker assembly including the interrupters should behoused in the SF6 environment. Enabling a better phase to phase and phaseto earth insulation.Minimum no of shots on fault should be more than 40.

A single drive beam should connect the moving contacts of all the threeinterrupters. So as to achieve simultaneous arc interruption in all the threephases, when operated by a common mechanism.

The circuit breaker assembly should be complete with a disconnector cumearthing switch. Which will serve the dual purpose of isolating the circuitbreaker from the bus bar when not required and earthing the transformer feeder cables during maintenance.

The protection to the distribution transformer must be achieved through a self-powered, relay. The relay and the current transformers should be external tothe Gas Tank, to facilitate setting, monitoring, maintenance andreplacement.

CABLE CONNECTION COMPARTMENT

The cable connection compartment must be successfully tested according toDIN VDE 0670 part 6 or equivalent IEC for behavior in the event of an internaldefect. No insulating material on metal surface of the cable box is allowed toensure arc proof resistance in the cable connection compartment.

The cable connection compartments must be fitted with front covers to thefront.

The front covers must be integrated in the comprehensive interrogator interlocking system.

The cable doors should be removable/detachable type so as to facilitateeasy connection of cables and not to allow any hindrance to themaintenance staff while doing maintenance.No cable covers should be hinged type.

7/30/2019 7 RMU

5/16


The cable termination access for the functions (eg: Isolator/Load break Switchor Vacuum circuit breaker) should be from the front. Termination access fromthe sides and rear are not acceptable.

CABLE FEEDER

The ring main units must be equipped with outer cone connection bushingswith M16 inside thread.

The cable connection compartment of the cable switches or the isolatorsmust be dimensioned in such a way that1. Surge arrestors2. Parallel cables

Can be installed behind he closed cable front covers.

The connecting points of each outgoing feeder must be horizontally situatedin one level at a suitable height from the bottom line of the unit, for easyconnection.

The cable brackets inside the cable connecting compartments must bevertically and horizontally adjustable.

TRANSFORMER FEEDER

The transformer feeder must be equipped with outer cone bushings for boltedcable connection systems.

The cable connections at the transformer feeder must be accessible from thefront.Lateral or rear situated connections will not be accepted.

It must be possible to connect the transformer cables by means of straight or angled plugs depending on the available space without exceeding the outer dimensions of the ring main unit. It must be possible to fix the transformer cables with adjustable cable mounts on to the ring main unit.

CABLE TESTING

The cable testing must be possible without dismounting the cable plugs andcables.There should be the facility of opening the cable covers and do the cabletest ensuring physical visual inspection of the cable test plugs and cables.The facility for cable testing should be available in the cable box of isolatorsand as well as circuit breakers.The cable testing for transformer feeder should even be possible when thebusbars are live.

7/30/2019 7 RMU

6/16


INSTRUMENT RECESS

The indication devices at the front side of the panel have to be placed on thetop of the switchgear ensuring no bending of the operator / personal.

It must be possible to integrate the following devices in the instrument recess:

1. Capacitive voltage detection system or live Line Indicator 2. Short circuit indicator 3. Pressure gauge

OPERATION AND CONTROL

There must be a user friendly control panel with a single line diagram andintegrated position indicators for all switching devices at the front side of theswitchgear.

The following performances must be possible while the front panel is closed:

a. Inspection of gas pressure.b. Switchingc. Mechanical position indicatorsd. Mechanical operatione. Voltage indication.

INTERROGATOR INERLOCKING SYSTEM

The switchgear must be equipped with a comprehensive interrogator interlocking system, which prevents any inadmissible control process anddoes not allow any mal-operations.

The following mutual interlocks should be possible:

Load break switch - earthing switchEarthing switch - cable front cover Earthing switch - Circuit Breaker covers

ACTUATING UNITS

The plug in holes /access for hand crank or drive sockets, for load break switches and those for earthing switches should be distinctive and should bemechanically connected to the respective position indicator. The operating

7/30/2019 7 RMU

7/16


handles for the load break switches and earthing switches must be distinctiveand must also have different colour.

PROTECTION WHEN OPERATING AND WORKING

The safety of the staff while working and operating must be ensured.

The following protection categories must be met in order to protect one fromdirect touching of live parts according to DIN VDE 0670, part 6, IEC 60298.

1. IP3X for the drives and the secondary equipment2. IP67 for the main circuits

To protect one from the effects of an internal fault, the switchgear along withcable-box must be type-tested for internal arc at 21kA for 1 Sec. Theprotection rating below this is not acceptable. This is to ensure the maximumsafety of the switchgear.

SECONDARY EQUIPMENT

When required, the ring main unit can be equipped with the following controland operating devices:

VOLTAGE DETECTING SYSTEM

Every cable feeder and transformer feeder must be equipped with a 3-phaseintegrated voltage detection system.The energy for the system should be from the coils present at the outer cone

of connection bushings.

FAULT PASSAGE INDICATOR

As a option, it must be possible to fit every cable feeder with Fault PassageIndicators which can easily be watched on the front panel.

The transducers for the short circuit indicators have to be mounted onto theouter cone of the connection bushings or on the incoming cables to the RMU.The display of the FPI should by LEDs/LCD.It should be capable of indicating the phase and ground faults.

MOTOR DRIVE

It should be possible to change the manual drives of the load break switchesto motorized drives at site.

The motor drives have to be integrated into the recess of the drives.

7/30/2019 7 RMU

8/16


All the mechanical interlocking must also work when the load break switchesare operated by a motor drive.

In case of power failure of the auxiliary voltage the manual operation of theswitching devices must be possible by means of an operating handle.

RELAY

The relay should self-powered /CT powered type. Preferably, combinationof a compact protection relay and related ring type transformer shouldprovide the protection.

The relay should provide time over current protection and earth faultprotection functions in a well proven technique for CT powered protectionrelays.

The following functions should be realized:-1. 3 phase definite time overcurrent and short-circuit

protection with variable tripping times.2. 3 phase overcurrent protection with selectable inverse time

characteristics and definite time short circuit currentelement.

3. Earth current protection. ___________________________________________________________________

Technical Data

a) Switch-disconnector function C

The switching-unit should be designed as a three-position-switch. This three-position-switch combines the functions of Load break switch and earthing-switch.The load break isolators for Incoming and Outgoing supply must be providedand the load break isolators are fully insulated by SF6 gas. The load break isolators shall consist of 630 Amp fault making/load breaking spring assistedring switches, each with integral fault making earth switches. The switch shallbe naturally interlocked to prevent the main and earth switch being switchedON at the same time. The selection of the main and earth switch is made bya lever on the fascia, which is allowed to move only if the main or earthswitch is in the off position Each load break switch shall be of the triple pole,simultaneously operated, non automatic type with quick break contacts andwith integral earthing arrangement.

b) Circuit breaker T2

This function-unit consists of a circuit breaker in combination with a three-position-switch The circuit-breaker-unit T2 should be equipped with aovercurrent-time-release for the protection of distribution transformers.The SF6/VCB circuit breaker must be a spring assisted three positions withintegral fault making earth switch. The selection of the main/earth switch lever

7/30/2019 7 RMU

9/16


on the fascia, which is allowed to move only if the main or earth switches is inthe off position.The circuit breaker shall be fitted with a mechanical flag, which shall operatein the event of a fault (electrical) trip occurring. The tripped flag should bean unambiguous colour differing from any other flag or mimic.

c) EARTHING OF ISOLATORS AND DISTRIBUTION TRANSFORMER BREAKERS(EARTH SWITCH)

Necessary arrangements are provided at Load break isolators / Transformer Breaker for selecting Earth position. Mechanical interlocking systems shallprevent the RMU function from being operated from the ON to Earth Onposition without going through the OFF position.

d) BUSHINGS

The units are fitted with the standardized bushings that comply with IECstandards. All the bushings are the same height from the ground and areprotected by a cable cover.

Operating Conditions:

Installation altitude above sea level < 1000 mIndoor conditions: relative air humidity according to DIN VDE

0670, part 1000; IEC 60694;IEC 60694

Ambient air temperature max. +40C; average value24 h +35C; min. -5C

Standards and Regulations:

Installation, building dimension, room type VDE 0101Operation, control, work near live parts VDE 0105, part 1Construction, design, tests VDE 0670, part 6; IEC

60298Disconnector and earthing switch VDE 0670, part 2; IEC

60129

Type:

Version Non-extensible / extensibility atboth sides

Auxiliary Voltage for motor drive & trip coil:DC 24V, 110V,AC 220/230V

7/30/2019 7 RMU

10/16


Electrical Data:

Rated voltage 12 kVRated operating voltage 11 kVRated frequency [Hz] 50/60Rated power-frequency withstand voltage 28 kVRated lightning impulse withstand voltage 75 kVRated short time withstand current 20 kARated short-circuit duration 3 sRated peak current 50 kARated current (Bus-Bar) 630 A

Standard Equipment

Voltage detection system Capacitive voltage detectionsystem, one per phase.

Manometer SF6 indication should betemperature compensated.

Front cover with 1 cable per suitable for even 2cables per phase

Cable clamp One per cable box.

Cable connection Bolted type

Position indicator Load break switch Black

Position indicator Earthing switch black

Current path colour grey

Pressure relief:Cable compartment To the bottom

7/30/2019 7 RMU

11/16


TECHNICAL SPECIFICATION FOR RMU

I. 11KV Bus Bar

Type of material : Copper Current Carrying Capacity : 630 Amps.Short time rating current for 3 secs. : 20 KAInsulation of bus bar : SF6Bus bar connections : Anti-oxide grease

II. Parameters for Switch Gear of Load break isolators and CircuitBreakers in RMU.

Type : Metal enclosedNo of Phases : 3No. of poles : 3Rated voltage : 12 KVOperating voltage :11 KV(+10% to 20%)Rated lightning impulse withstand voltage : 75 KV Rated power frequency withstand voltage : 28 KVInsulating gas :SF6Rated filling level for insulation :0.3 bar/As Per IEC. Max.permissible site altitude at the above gas pressures : 1000m(The operating pressure has to be adjusted for greater altitudes)

Rated short time current :20 KA.Rated short time :3sRated peak withstand current :50 KA.

Operating mechanism: Circuit breaker with spring assistedMechanism.

Rated current (Bus): : 630 ARated current (breaker) :630 ACircuit Breaker interrupter : VCB Rated frequency : 50 Hz Rated operating sequence : O-3min- CO

Number of mechanical/Remote operations for earthing As per IEC

& Ring switches & Number of mechanical/ 60298remote operations for circuit breakers

7/30/2019 7 RMU

12/16


III.PRINCIPAL FEATURES

SlNo

DESCRIPTION DTbreaker

1 Circuit label Yes2 Mimic diagram Yes3 Voltage indication Yes4 Current Transformer Yes5 Self Powered based Microprocessor

based IDMT RelayYes

6 Interlock to defeat the operation ofthe line side earthing when the lineside isolator is ON.

Yes

7 Interlock to defeat the operation ofthe earthing when the breaker is inservice position and is ON.

Yes

8 Breaker ON/OFF indication Yes9 On - OFF indication / Spring assistedmechanism.

Yes

10 Fault Tripping indication Yes11 Whether the SF6 gas pressure gauge

indicator and filling arrangement.Yes

12 Operating Handle for the springassisted mechanism.

Yes

13 Whether the earth positions witharrangement for padlocking in eachposition and independent manual

operation with mechanicallyoperated indicator are provided

Yes

IV.3 Load break switch (Isolators)

Type : SF6 load breaking and faultmaking.Rated current : 630 A

Fault making capacity (KA peak min.) : 50 KA

V. Earthing switch for L B S and CB of RMU.

Rated short time current : 20 KA. Rated short time :3sRated peak withstand current :50 KAInterlocking facility: 1) Between 11 KV Line side isolator ON& Earthing.

2) Between Earthing switch and the Cable Cover..

7/30/2019 7 RMU

13/16


VI. Current Transformers for breaker

CT Type : Cast resin / Tape wound

Rated burden : Suitable for self powered relay.

TESTS:TYPE TESTThe bidder should, along with the tender documents, submit copies ofall Type test certificate of their make in full shape as confirming torelevant ISS/IEC of latest issue obtained from a Govt. Lab/InternationalRecognized laboratory/KEMA/CESI

TYPE TESTS 1. Impulse Test with breaker inside the

cubicle2. Arc Fault test3. Temperature rise test with breaker inside

the cubicle.4. Short Circuit Test with breaker inside the

cubicle.

5. Dielectric Tests

6. Test of Apparatus Ie circuit breaker andearthing switches.

ACCEPTANCE AND ROUTINE TESTS All acceptance and routine tests as stipulated in the latest IEC- shall becarried out by the supplier. The supplier shall give at least 7 daysadvance intimation to be enable to depute our representative for witnessing the tests.

GUARANTEE:

The equipment/ supply will be guaranteed to perform trouble freeservice for five years from date of commissioning. Any deficiency in

performance for five years will be made up free of cost by the supplier either by replacement or by repairs.

7/30/2019 7 RMU

14/16


Mandatory Facilities which the vendor must posses;-

1) Micro-ohm and circuit breaker testing via computerized analyzer machine.

2) Computerized SF6 filling and testing facility.3) Partial Discharge lab for conducting the partial discharge and high

voltage test on the complete product.It is mandatory to have the complete assembled tank tested for partial

discharge to ensure a high life and reliability of the product.

ROUTINE TESTS

STANDARDIEC60298

1Withstand Voltage at power Frequency for all current carryingparts including wiring

2Measurement of Resistance of theMain Circuit.

3 Gas Leakage Test4 PARTIAL DISCHARGE TEST

5Withstand Voltage onAuxiliary Circuit.

6Operation of Function Locks, Interlocks, Signaling Devices andAuxiliary Devices.

7Suitability & correct operation of Protection, Control Instrumentsand electricalconnections of the circuit breaker operating mechanism (PRIMARY &SECONDARY INJECTION)

8 Verification of Wiring.9 Visual Inspection.

7/30/2019 7 RMU

15/16


Guaranteed Technical Particulars for Extensible/ Non-extensible SF6 insulatedRing Main Unit

1.1.1. Switchgear Data1 Service2 Type3 Number of phases4 Voltage5 Rated Frequency6 Rated Current7 Short Circuit rating

Breaking (breaker)8 Short time withstand 3S

Fault making9 Insulation Level

10 System earthingB Vacuum or SF6 Circuit Breaker1 Type2 Rated Voltage3 Breaking Current4 Making Current5 Rupturing Capacity6 Rated Current7 No. of Poles8 Operating mechanism9 Breaker Operating Time

i) Break Time msec.ii) Make Time msec.iii) No. of Operations

a) At full load current

b) At Fault CurrentC

Isolators1 Type

2 Duty cycle

3 Rated current4 Rated breaking capacity

5 Fault making capacity

6 Rupturing Capacity

7/30/2019 7 RMU

16/16


7 No. of poles

8 Operating mechanism

9 SF6 tank

10 Interlocks

11 Operation safety

D Busbars:1 Material2 Type3 Rated Current4 Short time rating for 3 Sec.E

Cable BoxesAir Termination

F Current Transformer 1 C.T. Ratio2 Over current factor3 Class of accuracy4 Rated BurdenG Configuration

(Left to Right facing front of RingMain Unit)

H Protection1 Three phase over current and

Earth Fault

1. Deviation Sheet (Technical and Commercial):

If the proposal has got any deviation from the Technical and Commercialspecifications, the bidder shall tabulate these deviations clause in theschedule. Add more sheets if required.

Literature of Ring Main Unit with SF, Oil Switch, SF6, VCB's

Documents

7 RMU