11 kv switchgear 31.5ka

8/10/2019 11 Kv Switchgear 31.5kA

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3.1

12 KV, 31.5 KA METAL CLAD SWITCHGEAR:

3.1.1 Switchgear:

The switchboard offered shall be of the conventional indoor totally enclosed metal-clad type with

either horizontal or vertical draw out, vacuum circuit breaker. The busbars shall be of hard drawnhigh conductivity copper bars, air insulated and Heat Shrink Sleeve covered for busbar Insulation

(painting on busbar is not acceptable). Suitable moulding should be used to shroud the joints. Size

of busbars shall be clearly stated. The switchboard shall be of robust construction and shall be

unaffected, in whole or in part, by the forces imposed by short circuits or other fault currents,operation, installation, vibration or changes in temperature. The switchgears must be capable of

withstanding 11 KV line to earth fault current indefinitely under emergency conditions. Theswitchgear shall be strictly in accordance with B.S: 5227 or IEC 298 unless specified otherwiseherein. The busbars on all switchboards shall be arranged to permit future extension at each end.

Phase rotation and colour markings shall be in accordance with BSS 158. All instruments,

instrument transformers, other components and compounds used in the switchgear and in the circuitbreakers shall comply with the appropriate and latest British Standard Specification or at least

equivalent to it. The switchgear shall be fully interchangeable. The switchboard shall be arranged forbottom entry of 11 KV cables and pilot cables as shown in drawing No. MB/7/634. Fixing bolts ofall of the removable covers of the switchgear shall be fixed through welded nuts. The circuit breaker

compartment of the panel shall be provided with front door.

The circuit breakers shall have 3 positions, viz., SERVICE, TEST and ISOLATED. In the testposition, it should be possible to close the door of the circuit breaker chamber.

The minimum thickness of steel plates for the cubicle shall be as follows :-

1. Bottom plate thickness : 3 mm

2. Front door for C.B. chamber thickness : 3 mm

3. Frame thickness : 2 mm

4. Front door for instrument compartment thickness : 2 mm

5. Cover for cable box thickness : 2 mm

6. Flaps thickness : 0.5 mm

3.1.2 Earthing Gear:

Provision shall be made for earthing of the power cables of each unit. The earthing arrangement shall

be one of the following:

a)

Through the circuit breaker by the method of transfer position without the necessity of anyloose attachments or devices (i.e. integral earthing).

b)

Through a fault making earth switch fully interlocked. The switch shall be of the quick-make-break type. Visual checking of the earthing switch shall be possible through

transparent covers. However, the earthing switch chamber shall be vermin proof and dustprotected.

Operation of earthing switch must be from the front of switchgear with CB compartment doorclosed .

Earthing devices shall be fully interlocked with the circuit breaker and shall be capable of closing on

full short circuit current corresponding to 31.5 kA at 12 KV without sustaining any damage orendangering the operator. The short time current rating must not be less than 31.5 kA for 3 seconds.Type test certificate for earthing devices should be submitted with the offer. Earthing device shall be

operated from front of the panel and to be marked clearly.

3.1.3 Duty of Plant:

a)

Rating:


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All current carrying parts of the switchgear including current transformers, isolatingcontacts, busbars, connections and joints shall be capable of carrying their specified rated

current continuously under Kuwait Climatic conditions and the temperature rise in Kuwaitshall comply with B.S. 5311 and 159 and any other applicable relevant British StandardSpecification. Tenderers shall state the B.S.S. ratings along side the Kuwait rating in each

case.

b)

Circuit Breakers:

The circuit breaker shall be of the vacuum type and shall have guaranteed rupturing capacity

of not less than 31.5 kA at 12 KV and must conform to BS 5311 taking into account the

climatic conditions of Kuwait. The circuit breaker should be capable of carrying full shortcircuit current associated with the above fault level at 12 KV for a duration of 3 seconds

without any damage and shall have :-

i) The vacuum shall serve as an arc extinguishing as well as insulating media.

ii)

Tenderers should explain clearly in their offers how the degree of vacuum is

maintained and whether the C.B. is suitable for periodical checking of vacuum.

iii)

The loss of vacuum per year, if applicable has to be given in guarantee

schedule. Tenderers must fill the appropriate details in the schedule of General

Particulars and Guarantees with complete and clear technical data.

iv)

All live parts of C.B should be completely insulated when it is plugged in

service position.

One circuit breaker shall be tested for 95 KV. Impulse withstand voltage at no extra cost.

Each and every tender shall be accompanied by a short circuit type test certificate (for theabove rupturing capacity) for the switchgear offered, from an independent acknowledged

international testing laboratory (ASTA / KEMA / CESI, ), and the tests shall be done atthe laboratory origin country, while tests done in other lab and witnessed by one of

the above approved independent acknowledged international testing laboratory willnot be accepted .

The above testing certificate shall be for switchgear manufactured by the company who will

be manufacturing and supplying the switchgear under the contract.

Tenders not complying with the above will be rejected.

c)

Normal Rating:

630 Amps shall be normal continuous rating under Kuwait worst temperature conditions.

3.1.4 Operation:

Hand charged spring closing mechanism shall be provided. An indicator shall be fitted clearly

indicating whether the spring is in the charged or uncharged state. Closing to be affected by

means of a 50 volts D.C. spring coil, through a local barrel type control switch.

The construction of the control switch shall be such that all the contacts are properly shielded anddust protected. Means of manual closing shall also be provided. Mechanism shall be fitted with a

local manual spring release push button shrouded to prevent inadvertent operation and provided withmeans of padlocking.

Tripping shall be by means of a 50 volts D.C. shunt trip coil. Manual trip also is to be provided.


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Mechanical ON/OFF indicator shall be provided. The charging and operating mechanism chambershall be dust protected.

Mechanical operation counters shall be provided in all circuit breakers .

3.1.5

Live Parts Isolation and Shutters:

Each switchboard must be provided with approved means of isolation of circuit breakers andcircuits, and to be complete with automatic shutters to screen off all live parts. The shutters for thefeeder and busbar spouts shall be operated independently and must be suitable for the arduous

Kuwait conditions without any deformation. The switchgear must be fully interlocked to prevent

unauthorized or mal-operation. Safety of personnel and continuity of supply are the primeconsiderations. Locks, each with two keys shall be included in the tender price for:

a- Locking out circuit in the isolated position.

b-

Locking circuit breaker control.

c-

Locking movable shutters screening live parts.

To facilitate phase out of any incoming circuits against busbar, arrangements shall be provided to

enable easy manual opening or closing of any of the above shutters independently with the circuitbreaker withdrawn and provision of locking of these shutters independently in the open and

closed positions.

To facilitate testing, device shall be provided for keeping shutters in an open position when movingportion (trolley) is withdrawn. This device shall be cancelled in insertion of moving portion,

ensuring that regular automatic operation of shutter is restored.

3.1.6 Racking Equipment:

The racking equipment shall be an integral part of the circuit breaker.

A wheeled carriage for the removal of the circuit breaker from a switchboard shall be an integral part

of the circuit breaker (cassette type circuit breakers shall not be accepted). Suitable external guiderails shall be provided for fixing in the substation floor in front of the switchgear for guiding thecircuit breaker during its removal from the board.

3.1.7 Cable Boxes:

a)

Power Cables:Each cable dividing box on the feeder units shall be suitable to receive 3x300 sq. mm. AL orCU/SC/XLPE/SC/SWA/PVC 11 KV cable ( will be supplied by others ) . Bi-metallic cable

lugs suitable for the BICC UK or CEMBRE Italy crimping tools available with (MEW)

are to be supplied inside the cable end box with the necessary bolts, washers and nuts. BrassCompression Cable Glands outdoor type (type CW size 90) to BSS: 6121 part 1 are to be

supplied. The cable gland shall be complete with a heat shrinkable sleeve. The earth tag of the

cable gland shall be 5 mm. thick provided with a threaded hole and the necessary washers and


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bolt for connection of the copper earth strip. The gland is to be connected to the Main Earth

Bar.

Each cable dividing box on the transformer units shall be suitable to receive 3x300 sq. mm.AL or CU/SC/XLPE/SC/SWA/PVC 11 KV cable. Copper cable lugs suitable for the BICC

UK or CEMBRE Italy crimping tools available with (MEW) are to be supplied inside the

cable end box with the necessary bolts, washers and nuts. Brass Compression Cable Glands

outdoor type ( type CW size 90 ) to BSS: 6121 part 1 are to be supplied. The cable glandshall be complete with a heat shrinkable sleeve. The earth tag of the cable gland shall be 5

mm. thick provided with a threaded hole and the necessary washers and bolt for connection

of the copper earth strip. The gland is to be connected to the Main Earth Bar.

11 KV Heat/Cold Shrinkable Termination Kits comprising of non tracking stress controltubing, insulation sleeves, etc. suitable for 3x185 - 3x300 sq. mm. AL or CU/SC/XLPE/SC

/SWA/PVC 11 KV cable along with Heat/Cold Shrinkable Right Angle Boots or Straight

Boots, are to be supplied with each feeder /transformer cable dividing box. A sample is to besubmitted for the purchasers approval.

The vertical distance between the cable crutch and the cable connection terminals shall not

be less than 570 mm in any case for all feeder/transformer cable dividing box. The gland

plate for the power cable should be at least 350 mm above the ground level.

The terminations shall be covered to render electrical protection and safety to personnel.

The boxes shall be designed with ample dimensions with removable bottom gland plate

and back cover to facilitate jointing and to allow crossing of cores without damage to

insulation. The boxes and terminations shall be subject to the approval of the Purchaser. Allthe boxes shall be bolt-on-type.

b)

Multicore cable cabinet:

The 11 kV switchgear shall be provided with multicore cable cabinet on the back of eachpanel. The cabinet shall be capable to receive either 16-core, polyethylene insulated and

sheathed, steel wire armoured and overall PVC sheathed pilot cables or multicore cablefrom (common integrated safety device, PRV and themometer from transformer room in

case of oil immersed transformer ) or from (Thermal Relay in case of Cast ResinTransformer ).

Each Multicore cable cabinet shall be provided with suitable terminal blocks.

Each Multicore cable cabinet shall be provided with super deluge proof compression type of

brass cable gland of Size 1`` with earth tag which shall be connected to the Main Earth Bar.

3.1.8.

Current Transformers:

Current Transformers may be either air insulated type or cast resin type. Current

transformers shall be so rated that they will not sustain any damage by the through faultcurrents expected on a system level of 31.5 kA at 12 KV. All secondary windings shall be

one ampere unless otherwise specified. All the secondary wires of the current transformers

shall be brought to an accessible terminal block in the control panel.

All current transformers shall comply with the relevant British Standard specification and the

current transformers for Solkor protection shall conform to the conditions stated below underProtection.


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Current transformers shall be capable of withstanding full short circuit current for 3 seconds

without distress or damage.

Proper barrier is to be fixed in between the C.T. Chamber and the cable termination box.

3.1.9.

Circuits:

Each circuit breaker will control either (a) a feeder circuit or (b) a power transformer circuit.

3.1.10.

Protection:

a)

Feeder Circuits.

Each feeder circuit shall be protected by UNIT FEEDER PROTEECTION comprising of

Solkor RF 5 KV feeder protection using relays and associated equipment manufactured byReyrolle (Siemens Protection Devices Ltd ) at Hebburn, Tyne & Wear, United Kingdom. Itshould be possible to set the relay in both Solker R or Rf mode. The relay should be supplied

in a 1V size flush mounting Vedette style case with built in test facility. The current

transformers shall be of ratio 400/300/1A, of 15 VA capacity and class X accuracy, and theyshall have characteristics matching with the current transformers already connected to the

system. A separate 400/1 current transformer of class 1 accuracy shall be provided for

metering purposes. Attention is drawn to the requirements for the satisfactory operation ofSolkor RF feeder protection published by Reyrolle (Siemens Protection Devices Ltd ), in

their Technical report No. 990/TIR/005/02 titled "Current transformer Requirements for

Reyrolle Protection Relays " .

The through fault current shall be 31.5 kA at 12 KV. The successful tenderer shall submit a

Magnetization Characteristics Curve and Ratio Error Curve under the burden conditions

applying to the Solkor RF protection over the range of through fault current.

The Purchaser shall approve in writing the characteristics curves for the current transformers

before manufacture can proceed.

Alternatively, unit feeder protection (other than Solkor RF feeder protection) manufactured

by other companies may be offered. However, the unit feeder protection should match with

solkor RF of M/s. A. Reyrolle and guarantee for the performance of these relays should besubmitted along with each and every offer.

For feeder circuits the existing Solkor R 5 KV relays can be used with the new type SolkorRF 5 KV relays by means of changing four links internally in the Solkor RF relay andthese shall be carried out by the contractor of this tender without any extra cost.

b)

Transformer Circuits:

Each transformer circuit shall be protected by non-directional over current and earth leakagerelays.

The overcurrent relays shall be of the inverse definite minimum time lag type (IDMTL). Therelays shall have a current setting of 50 200% in steps of 25 %. The time setting shall be 3

seconds at 10 times plug setting with time multiplier setting at 1 and shall be adjustablebetween zero and unity and shall have characteristics to BSS 142.

The earth leakage relay shall also be of the inverse definite minimum time lag type(IDMTL). The relay shall have a current setting range from 10% - 40% in steps of 5 % andtime setting adjustable from zero to unity and time setting shall be 3 seconds at 10 times plug

setting with time multiplier setting at 1, having characteristics to BSS. 142 with 100/1,

15 VA, class 10 P 10 current transformer.

The over current relays shall be equipped with high set instantaneous current elementshaving setting of 8 Ins. to 20 Ins. and with steps of 2 Ins. and ending with infinity.


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Trip contacts from common integrated safety device, PRV and thermometer from thetransformer ( in case of Oil Immersed Transformer ) shall be wired for tripping the circuit

breaker through suitable inter-trip relay ( three elements ) with a 50 volts supply andmechanical hand reset flag indication, or trip contacts from Thermal Relay (in case of CastResin Transformer) shall be wired for tripping the circuit breaker through the same inter-trip

relay.

c)

Loose Feeder Panels:

This shall be provided with main protection as per 3.1.10 (a) above and back-up protectionof non-directional O/C and E/L relays similar to that under 3.1.10. (b) but with setting range

of 20% to 80% (for earth leakage only) and the CT ratio 400/200/1 15 VA class 10P10. Alsothe loose feeder panel shall be provided with a separate 400/1, 15 VA, Class 1 currenttransformer for metering, and suitable inter-trip relay ( three elements ) with a 50 volts

supply and mechanical hand reset flag indication to trip C.B when the panel is used as

transformer panel.

d) Loose Transformer Panel:

This shall be same as 3.1.10 (b) but with CT ratio 400/200/1 15 VA class 10 P 10 and anammeter with 0-240/0 480 Amps, Trip contacts from common integrated safety device,

PRV and thermometer from the transformer ( in case of Oil Immersed Transformer) shall be

wired for tripping the circuit breaker through suitable inter-trip relay ( three elements ) with a50 volts supply and mechanical hand reset flag indication, or trip contacts from ThermalRely ( in case of Cast Resin Transformers ) shall be wired for tripping the circuit breaker

through the same inter-trip relay.

NB: All relays shall be flush mounting pattern, self resetting type with hand re-set flag

indicators.

Unless otherwise stated in the specification, all relays shall be manufactured by one of thefollowing companies:

- M/s. Reyrolle (Siemens Protection Devices Ltd ) - United Kingdom.

- M/s. AREVA T & D (Alstom) - England.

- M/s. Siemens - Germany- M/s. ABB - Sweden.

All relays shall be electromagnetic type, electronic type relays will not be accepted.

3.1.11.

Intertrip Circuits:

The existing system has a number of Ring Main substations that will require intertripping relays tobe installed on the feeder panels covered by this tender incase these are installed between or adjacent

to those existing substations.

Therefore, each feeder C.B. panel shall have space and connection facilities for a possible futureaddition of an intertripping relay of Reyrolle flush type No. B12 or similar suitable for use with a 50

V D.C. supply. Necessary provision for intertripping relay space and auxiliary contacts shall be

arranged for such requirements. These panels can be pre-drilled and fitted with blanking plates forthis purpose.

3.1.12. Auxiliary Switches:

Auxiliary switches shall be provided to interrupt the D.C. supply to trip coil immediately after their

operation has been completed.

All necessary auxiliary switches for indication, protection control, supervisory and other services,plus two spare ways normally open and two spare ways normally closed shall be provided on eachC.B. panel. These switches shall be wired to a suitable terminal box on the back of panels.

All switches shall be of robust pattern with wiping contacts and shall be fitted in easily accessible

positions adequately protected.


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3.1.13.

Healthy Trip Indication:

15 Watt 50 volts D.C. lamp with series limiting resistance operated through a spring loaded push testswitches shall be provided.

3.1.14.

Group Alarm:

The automatic and manual tripping of each C.B. in the substation shall close a two wire circuit to

operate the remote alarm and indication relay, located in concerned control center. Re-set of the

alarm indication shall be done by the C.B. trip and close control switch.

3.1.15 Miniature Circuit Breaker for control circuit

All MCBs used in 11 KV switchgear control circuit shall be fitted with auxiliary contacts for MCBtripped alarm .

3.1.16.

Instruments:

Dial type switchboard pattern, flush mounted, M I ammeters shall be provided where stated in theattached schedule of equipment. A moving iron switchboard pattern ammeter shall be connected to

yellow phase and shall have a reversible scale graduated to suit C.T.s double ratio for loose

transformer panel.

3.1.17.

Test Terminal Blocks:

Over current and earth leakage transformer secondary wiring shall be connected through terminalblock provided with change over links to permit easy ratio change and testing.

The terminal block shall be mounted in front of the panels and suitable insulated and provided with a

detachable dust proof cover.

3.1.18.

Pilot Cable Terminations:

It is the general practice in Kuwait to lay one multi core pilot cable with each 11 KV feeder cable.

The pilot cable shall be terminated at the rear of its 11 KV C.B. panel, in a suitable terminal cabinet

arranged to give easy access to the terminations and fitted with suitable cable glands with earth tagas specified. Each terminal block shall be of the circuit selector type with insulated bridging plugs.

The terminal block shall be arranged to receive multi-core cable and switchboard services. Bus-wiresbetween terminal cabinets shall be provided to enable circuit routing and selection.

The multi-core pilot cable provides the following services:

i)

One pair : of 2.5 sq. mm. conductors for solkor feeder protection pilot Cores.

ii)

Two pairs : (do) inter-trip and interlock circuits.

iii)

Two pairs : of 0.625 sq. mm. conductor for substation telephone services,

Marked T1, T2, T3 & T4.

iv)

Three pairs : (do) remote alarm and indication circuits with one core commonreturn and five separate route circuits.

Each feeder panel shall be provided with the following services:

i)

One pair : Solkor protection circuit.

ii)

One pair : Inter-trip circuit.

Each substation switchboard shall be provided with the following marshalled through a terminal

block located at the rear of transformer C.B. panel:i) One pair : To telephone hand-set desk, located in the substations.

ii) One pair : Group alarms and remote indication.


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iii) One pair : 50 volts D.C. supply from tripping battery to the switchboard.

NB: All outgoing circuits to the services, inside the substation shall be 2.5 sq. mm. stranded copper

cables inside galvanized conduit.

3.1.19.

Loose Extension C. B. Panels :

3.1.19.1

Loose Extension C. B. Feeder Panels:

These units shall be complete with 11 KV circuit breaker and suitable in all respects to

form extension to the 4-panels or 6-panels Ring Main Switchboard. These loose extensionunits shall be supplied with all the fittings, busbar joints, heat / cold shrinkable termination

kits, cable lugs and cable glands etc. for future installations as an integral part of any 4-

panels or 6-panels switchboard.

3.1.19.2

Loose Extension C. B. Transformer Panels:

These units shall be complete with the 11 KV circuit breaker and suitable in all respects to

form extension to the 4-panels or 6-panels Ring Main Switchboard. These loose extensionunits shall be supplied with all the fittings, busbar joints, heat / cold shrinkable termination

kits, cable lugs and cable glands etc. for future installations as an integral part of any 4 panel

or 6-panels switchboard.

3.1.20

Additional Equipments and Work:

The following equipments shall be supplied, the work shall be done, and the cost of theseshall be included in the tender price.

a) Tools:

Each switchboard shall be provided with a complete set of tools. The tools shall be housed ina tool rack suitable for wall mounting. Complete list of tools shall be submitted with the

offer. In addition, sixty (60) sets of complete tools (in a tool rack) to be supplied, as extra for

each type of switchgear offered

b)

Testing plugs:

Thirty (30) Nos. 3-phase sets of testing plugs for each type of switchgear fully insulated fortest voltage/current usually applied to switchgear and cables shall be provided. Terminals of

the plugs shall be suitable to receive flexible testing plugs capable of carrying current

up to 630 Amps.

c)

Auxiliary Jumper leads:

Each switchboard should be provided with one set of auxiliary jumper leads, for connectingauxiliary circuits between fixed and moving portions of circuit breaker when in the isolated

position for testing purposes.

d)

Special monitoring device : for vacuum CB`S:

In case the C.B. is suitable for the periodical checking of vacuum, four sets of portablemonitoring device shall be provided and the cost of such shall be included in the tender

price.

e)

The contractor shall do all the necessary arrangement and work to send tripping and alarmsignals from (Common Integrated safety device, PRV and thermometer fixed on

transformers in case of oil immersed transformers ) or from (Thermal Rely in case of Cast

Resin Transformers ) to the corresponding 11 KV switchgear panel.

The respective technical pamphlets of the above equipment to be attached to the offer.

3.1.21

Shutters for Busbars and Circuit Breakers:

For the safety in operation and maintenance of 11 KV switchgear panel, the Busbar shutters shall be

identified with red colour and the feeder shutters with White colour. Also the shutters shall be clearly


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marked with Busbar and Feeder respectively. Using stickers for marking is not acceptable. The

shutters for Busbar and cable shall be operated independently and not together. Phases identification

R, Y, B in colors shall be marked. Phases to be identified with color coded mark for Red, Yellow,and Blue. Using color stickers is also not acceptable.

3.1.22

Pressure Release Flappers:

The switchgear shall be provided with separate pressure release flappers at suitable locations ofvarious compartments to release the overpressure resulting from flashover that may occur. The

proposed arrangement shall be subject to the Purchasers approval.The pressure release flappers should be fast acting and should operate in less than 10 milli seconds.

Evidence of testing on at least one chamber at International laboratory to be provided.

3.1.23

HV indicator and phase comparator:

Each panel on 11 KV switchgear shall be equipped with three phase capacitive voltage indicatingdevice on the front of its operating panel to detect the presence or absence of operating voltage in the

cables .

These capacitive coupled device to be provided with the provisions for checking the synchronization

of phases and should comply with IEC 61243-5. Samples and catalogues shall be submitted forMEW approval .

The contractor shall supply 10 Nos. of phase comparator testing device with first delivery batch.

3.2 1250 KVA TRANSFORMERS:

3.2.1.

Type:

Three phase, oil immersed naturally cooled, core type power distribution transformer.

The transformer shall be in accordance with the International Electrotechnical Commission No.

60076 or with the latest British Standard Specification No. BSEN 60076 and BSS. 6435 orequivalent except where stated otherwise.

3.2.2.

Installation:

The transformer will be installed outdoor and may be exposed to direct sun rays and thus shall be

capable of carrying their full rated current under Kuwaits worst temperature conditions as specified.

3.2.3.

Normal Rating:

The normal rating shall be the maximum continuous rating under the worst temperature conditions

encountered in Kuwait (see climatic conditions).

Tenderers shall state in the schedule the equivalent British Standard specification or the International

Electro Technical Commission rating for the transformer offered.

The Kuwait continuous rating should not be more than 80% of the IEC Recommendations /British Standard specifications continuous rating.

3.2.4.

Voltage Ratio:

The normal voltage ratio of the transformers on normal tapping and no load shall be 11/0.433 KV.

3.2.5.

Duty Under Fault Conditions:

The transformers shall be capable of sustaining a three phase symmetrical short circuit current on theL.V. side with a fault power being maintained on the H.V. side and without damage to the

transformer for a period of three seconds(at tap position 3).

3.2.6.

Impedance Voltage:


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The impedance voltage at normal rating and voltage, and at 75 degree C shall be 6 % and stated in

the schedules.

3.2.7. Temperature Rise:

The transformers shall be capable of carrying its full normal rated current continuously under the

worst temperature conditions encountered in Kuwait, and at any tapping, without the temperaturerise of oil in the hottest region exceeding 35 degree C measured by the thermometer and that ofwinding 45 degree C as measured by resistance.

Any transformer exceeding the above temperature rise limits will be rejected.

3.2.8.

Connection & Ratio:

The transformers are to be wound to International Electrotechnical commission No. 60076 vector

symbol Dyn 11 with normal voltage ratio on normal tapping at no load.

3.2.9.

Cooling:

Cooling of the transformers shall be natural circulation of oil through the banks of plain externalcooling tubes or radiators suitably arranged. Due note being taken of the site conditions.

Transformers with corrugated tanks or cooling fins will be rejected. The radiators shall

physically be separate from the tank and shall not form integral part of the tank.

3.2.10.

Core:

The core shall be constructed of the best quality low loss, cold rolled, grain oriented electrical steel

laminations.

The flux density in any part of the core shall not exceed 1.6 TESLA at normal voltage and

frequency.All core plates shall be insulated from one another to reduce the loss to a Minimum, and the coreshall be held together by bolts and clamping plates all of which shall be adequately insulated.

The completed core shall be provided with lifting eyes to facilitate its removal from transformer tankand prevent movement during transport and/or service. Such fixing arrangement of the transformer

core must be adequate and strong enough to withstand the forces due to external short circuits. Allsteel sections used for supporting the core are to be thoroughly sand blasted after cutting, drilling and

welding. All steel sections shall be painted with powder coated. Design of supporting frames shalltake into consideration complete emptying of tank through a drain valve and the avoidance of

movement of the core relative to the tank during transport, installation and operation.

3.2.11.

Winding and Insulation Level:

The maximum current density in both H.V. and L.V. windings shall not exceed 265 amperes per

square centimeter as per the requirement of clause 3.2.7. All windings shall be made from highconductivity electrolytic copper conductors of best quality and shall be fully insulated to British

Standard Specification No. BSEN 60076 and for a system highest voltage of 12 KV. The insulation

shall be class A to British Standard specification No. 2757. The insulation level should be 75 KV

as per IEC 60076-3

The HV/LV winding shall be (CU.-CU.) and can be (wire / foil / sheet)

3.2.12.

Off Circuit Tapping:

Off circuit tapping shall be provided on the center (both electrical and mechanical) of the H.V.

windings. There shall be five tappings and arranged as follows:

Normal Voltage: 2.5% 5%


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The transformer shall be capable of operation at its rated KVA without injury on any tapping and any

applied voltage which does not vary from the voltage for which the tapping is rated by more than

5%. Tappings shall be connected to an externally operated off circuit tap changer switch providedwith clearly marked position indicator. Pad locking facilities and pad locks shall be supplied for the

switch and so arranged that the lock can only be inserted when the switch is on a definite tapping.The location of the tap-changer shall be in an accessible place. Special attention should be paid tothe oil seals around the tap changer rod. Each tender should be accompanied by detailed drawings

showing the sealing arrangement and any additional measures taken if any, to cope with Kuwait

conditions shall be indicated.

Tap changer switch shall be located on the side of the transformer tank and tap changer switchlocated on the top side of the tank will not be accepted. Minimum current rating of the tap changer

shall be 150 amps.

The tap changer switch shall be fully suitable for continuous operation under the specified working

and site conditions. A stainless steel engraved caution plate of adequate thickness and dimensions

stating that the tap switch to be operated only when the transformer is disconnected from both H.V.and L.V. Sides shall be fitted near the tap switch handle.

3.2.13.

Tanks:

The tank shall be constructed of mild steel of suitable sections with the necessary reinforcing section

and the whole shall be welded and fitted with bilateral rails.

Suitable lifting lugs must be provided to enable the transformer to be lifted by means of an overhead

crane and slings. Suitable lugs shall be provided on tank cover to facilitate its removal.The tank shall be fitted with an oil-drain valve. The tank shall be provided with 2 suitably located

earthing studs. The whole of the tank and fittings shall be sand blasted inside and outside to remove

all scale and rust before painting. All transformers shall be fitted with jacking lugs located at asuitable height from ground level.

The thickness of the side walls, top, and bottom of the tank shall not be less than 5 (five) mm.

The construction of the tank, particularly the cover, should be such as to prevent oil leakage under

the various load conditions. Constructional drawings shall be submitted which shall show the

constructional details to achieve this purpose.

3.2.14.

Conservator:

Conservator vessel shall be provided for mounting on the top of the tank. The conservator shall be ofample capacity for containing sufficient oil to allow for the transformer working over the maximumpermissible temperature range. Connections will be between the highest point of the main tank and

the conservator through common integrated safety device shall project four centimeters above the

bottom of the conservator in order to allow a dump of collection of moisture or sludge. Vent pipesshall be provided as required to prevent the trapping of air or gas in sealing ends, bushings or filling

cap and drain valve.

3.2.15.

Breather:

1 Kg silica-gel breather with replaceable elements shall be provided and connected by means ofgalvanized iron pipes to the conservator vessel. Oil or ball valve seals shall be provided to prevent

the circulation of air except under correct working conditions. A suitable observation window shallbe provided in the breather.

Breather having glass covers shall be provided with wire mesh or cages for protection, which can be

easily removed. The glass cover of the breather should be of good quality glass to withstand theweather conditions of Kuwait.


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3.2.16.

CommonIntegrated Safety Device:

The device shall be used for transformer protection by detecting oil level, discharge of gas, tank

pressure, and temperature. The device shall be fixed on a breathing transformer with expansion tank(1250 KVA Kuwait rating). The device shall be subject to approval by (MEW) engineers. Further,

this device shall withstand Kuwait atmospheric conditions as it may be used under direct sunlight(refer to climatic Conditions clause 2.5) the device shall be able to send trip signal to a circuitbreaker of transformer and shall also send signal to the switchgear room for alarm annunciation of

the device locally and provision to connect for telesignaling remotely via DMS. Common integrated

safety device shall comply with the following:

1.

Two simultaneous normally open contacts for gas discharge. It should note both thevolume of gases accumulated as well as the decrease in oil level. Contacts shall operatedue to a gas displacement (volume of gas collected) between 100cm and 200cm. Also,

Contacts shall operate if the oil level in the relay drops by the same volume as for gas

collection.2.

Two simultaneous normally open contacts for pressure.

3.

Two normally open contacts for temperature.4.

Pressure response time must be less than 5 milliseconds.

5.

Pressure indicator with a scale of 0 - 0.5 bar, and a display accuracy of +/- 0.05 bar.

6.

Pressure set point can be set and/or reset on site without the need of any special tools orcalibration.

7.

The relay shall be equipped with an easily accessible sampling petcock.8. Thermometer with maximum indication needle.9.

Venting valve for humidity and condensation drainage.

10.4mmindustrial terminal.

11.

Proper earth connection to ensure matching potential between the device and transformer

tank.12.

The device shall provide the ability to test all sensors (gas, pressure, and temperature)mechanically on site after installation.

13.

An evidence showing that the offered device has been in service for at least three (3)years to be submitted with the offer. Also a user list should be submitted with that.

3.2.17.

Pressure relief valve:

3inch T-type that evacuates any overpressure of oil and gas found in the oil tanks. The main

objective to operate in a very short period of time by evacuating the pressure increase. The

preset spring loaded device shall operate if pressure exceed 0.42kg/cm2, for 1250 KVA

transformers and reset to the normal position as soon as the pressure decreases below theabove mentioned value. The ejected oil and gas shall be directed towards a safe area. The

device should have an integral mechanical operation indicator with manual reset and twoN.O contacts. The device shall be accompanied by test certificates with values of operating

pressure.

3.2.18.

Thermometer:

A dial type thermometer with 2 normally open contacts shall be fitted to the tank of

transformer to read directly oil temperature in the hottest region of the transformer.

The fittings of the thermometer shall be such as to prevent the ingress of moisture.

A red mark should be engraved on the dial to indicate the maximum permissible oil

temperature.


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The thermometer shall be protected by a wire mesh or cage easily removable.

3.2.19.

Valves:

High grade gun metal oil valves provided with engraved coloured indication to show whether in the

open or closed position and with pad-locking devices to prevent an inadvertent operation shall befitted as follows:

-

Main tank drain valve.-

Conservator to main tank valve throw Common Integrated Safety Device-

Conservator drain valve

All drain valves shall be fitted with plugs or covers platers and having oil tight joints.

All the valves to comply to BS 5154, series b.

3.2.20.

Oil level Gauge:

An oil level gauge of an approved type shall be mounted at the end of the conservator vessel,particular care being taken that the oil is easily observed when partially obscured by dust as may beexpected under operating conditions.

The gauge shall have three markings indicating the level at 20o C and lower and upper markings

corresponding to the lower and the higher temperature for which the transformer is required to

operate on site.

3.2.21.

Gaskets:

All gaskets used for making oil-tight joints shall conform to B.S. Au.120/1966 and B.S.S. 3063/1965

as applicable, taking into account Kuwaits temperature conditions. A sample of gasket materialtogether with test report should be submitted to the Purchaser for approval. The material used for

gasket shall be cork-rubber and shall have very good resistance to transformer oil.

3.2.22.

Rating and Terminal Marking Plates:

Substantial brass or stainless steel diagram and rating plate in accordance with InternationalElectrotechnical Commission No. 60076 and British Standard Specification No. 171 shall be fixed to

each transformer giving full detailed information as follows:

Kuwait Rating : . . . . . KVA

IEC/BSS Rating : . . . . . KVA

Volts at no-load and normal tapping : . . . . . H.V. SIDE

. . . . . L.V. SIDE

Impedance voltage : . . . . . Percent (%)

Current at rated load and normal tapping : . . . . . H.V. SIDE

. . . . . L.V. SIDE


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Type of cooling :

Short circuit current / duration in sec : . . . . . K Amps/sec.

Impulse Voltage withstand (Insulation Level ) /power

frequency withstand voltage

:

Number of phases

Diagram of connection

:

:

Position of tap-changer switch corresponding todifferent voltages

:

Type of winding CU (Foil/ Sheet/ wire ). : . . . . . H.V. SIDE

. . . . . L.V. SIDE

Manufacturers Name

Transformer Serial No.

:

:

Contract No. :

Frequency :

Vector group reference and diagram :

Temperature rise of

I) Oil :

II) Winding :

Quantity of oil in litres :

Weight of core and winding in metric tons. :

Total weight in metric tons :

Year of manufacture :

The plates shall be of adequate thickness and the marking shall be engraved therein to a 0.5 mmdepth. The background being filled in black. Full details of rating plate shall be submitted for

approval. Also two Nos. substantial brass or stainless steel plates 200 x 150 mm. with the

transformer (circuit) No. engraved and coloured are to be fixed on the transformer at two differentplaces.

3.2.23.

Nuts and Bolts:

All nuts and pins shall be stainless steel and locked in position with the exception of those external to

the transformer, where locking may be omitted on receipt of the Purchasers approval.

Where possible it shall be arranged that in the event of nut working loose and falling off, the bolts

shall remain in position.

Where bolts and studs are so placed to be inaccessible by means of ordinary spanners, the contractorshall provide such special tools as are necessary.


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3.2.24.

Construction Details:

The overall construction and assembly of the transformers shall be robust and shall be renderedsuitable for the arduous weather and load conditions under which these transformers will operate.

Due to limited space available at our substations the overall dimensions of the transformer shall be inthe range of 2.60 M (height) x 2.50 M (length) x 2.30 M (width) between cable end boxes (measuredto the outside of cable end boxes). The contractors attention is particularly drawn to the following

requirements:

3.2.24.1

The coils bracing and tightening shall be such that the hum and vibration is kept to theminimum and shall be sufficiently strong to withstand the short circuit forces.

3.2.24.2

There shall be complete inter-leaving of laminations in joints cores and yokes.

3.2.24.3

Copper conductors shall be used for transformer winding.

3.2.24.4

Adequate ducts should be provided for oil circulation to avoid hot spot and heat pocketsin the following manner:

e) Axial ducts between H.T. and L.T. windings.

f)

Axial ducts between L.T. winding and core.

g)

Radial ducts in H.T. and L.T. windings.

3.2.24.5

Adequate insulation shall be provided at the end of the windings.

3.2.24.6

The transformers coils shall be vertically mounted.

3.2.24.7

Corrugated tanks or cooling fins will not be accepted. If radiators are provided, these

shall be separated from the tank and shall not form an integral part of the tank.

3.2.24.8

The sound levels shall be measured in accordance with BS 60076 10 and the values

shall comply confirm to NEMA. TR1 standard.

3.2.24.9

Location of tap changer switch shall be arranged on the side of the transformer tank. Tapchanger switch located on the top of the tank will not be accepted.

3.2.24.10

Terminal bushing on both H.V. and L.V. sides shall be arranged through the sides of thetransformer. Full details and drawings to show that the above requirements are included

shall be submitted with the offer.

3.2.24.11 The manufacturer has to clearly state in his offer the type of winding conductors offeredCU. (foil/sheet / wire). This has also to be clearly engraved on the rating plate.

3.2.25.

Cable Boxes:

The transformers shall be provided with cable end boxes on both high and low voltage sides. The

boxes shall be vertically mounted and arranged for bottom entry of cable and as follows:

H.V side:

The transformer cable end box on the high voltage shall comply with the requirements of B.S 6435

and shall be suitable to receive 3x300 sq. mm. AL or CU /SC/XLPE/SC /SWA/PVC 11 KV cable.


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Copper cable lugs suitable for the BICC UK or CEMBRE Italy crimping tools available with

(MEW) are to be supplied inside the cable end box with the necessary bolts, washers and nuts. Brass

Compression Cable Glands outdoor type (type CW size 90) to BSS: 6121 part 1 are to be supplied.The cable gland shall be complete with a heat shrinkable sleeve. The earth tag of the cable gland

shall be 5 mm. thick provided with a threaded hole and the necessary washers and bolt forconnection of the copper earth strip. The gland is to be connected to the Main Earth of thetransformer tank through a copper strip not less than 5x30 mm.

The box shall be designed with ample dimensions to facilitate jointing and allow crossing of coreswithout damage to insulation but the distance from the cable crutch to the transformer terminal

bushing shall not be less than 570 mm as specified in B.S.S. 6435, table 2.

The HV terminals of the transformers are to be marked clearly outside and inside cable end box.

Identification of the phases using stickers is not acceptable. The phasing order shall be ("R-Y-B" /

"A-B-C").

11 KV Heat/Cold Shrinkable Termination Kits comprising of non tracking stress control tubing,

insulation sleeves, etc. suitable for 3x185 sq mm - 3x300 sq mm. AL or CU/SC/XLPE/SC/SWA/PVC 11 KV cable along with Heat/Cold Shrinkable Right Angle Boots or Straight Boots, are

to be supplied with each transformer cable end box. A sample is to be submitted for the purchasersapproval.

L.V side:

The cable end box on the L.V. side shall be suitable to receive seven single cores 800 sq. mm.

stranded copper conductor cables (COPPER/XLPE/PVC non armoured) and shall be complete with

800 sq. mm. tinned copper cable lugs and compression type cable gland and PVC shroud of A2 type

to BS.6121 part 1. Any sort of wood material instead of brass type compression gland shall not be

accepted.

The L.V. box shall be designed with ample dimensions to render easy connection of cable. The

distance between bushing terminals and the bottom of the cable end box shall not be less than 350

mm. The bottom plate shall be of non-magnetic material.

L.V. cable end boxes shall be air insulated type and shall generally conform to B.S. 2562.

L.V bushing shall be monoblock type.

The LV terminals of the transformers are to be marked clearly outside and inside cable end box

Identification of the phases using stickers is not acceptable. The phasing order shall be ("b-y-r-n" /

"c-b-a-n")

The terminations shall be covered to render electrical protection and safety of personnel.

Both H.V & L.V side:

The gland plates at the bottom of the H.V and L.V cable end boxes shall be completely removable

from the outside, and shall be with condensation socket.

Suitable steel brackets complete with cleats and clamps of non-magnetic metal (wooden clamps of

any kind will not be acceptable) to support both high and low voltage cables, shall be provided. Thebottom of the cable glands of cable end boxes shall not be less than 600 mm. above the base of the

transformer.

The terminal bushing oil seals shall be subject to the approval of the Purchaser. Particular attention

shall be given to the tightening of all oil seals before the transformers leave the factory.

Detailed drawings for the cable boxes shall be submitted with each tender. These drawings shall

particularly show the spacing between bushings/live cores, connectors from each other and from any


17/32

earth object. The terminal bushings on both H.V. and L.V. side shall be arranged through the sides of

the transformer tank.

All the cable end boxes shall be bolt-on-type.

The LV and HV Cable end Boxes covers shall be provided with a rubber gasket, also the upper edge

of the cable box cover must be bent to prevent water ingress

3.2.26. TRANSFORMER OIL [unused uninhibited mineral insulating oil for distribution transformers (< 66 KV)] :-

The insulating oil shall be virgin, confirmed to IEC-60296 latest edition and all parameters specified in

Schedule "B-0", while tested at supplier's premises. The contractor shall furnish test certificates from the

supplier against the acceptable norms as mentioned in schedule "B-0", prior to dispatch of oil from

refinery to site. Under no circumstances, poor quality oil shall be filled into the transformer and onlythereafter be brought up to the specified parameters by circulation within the transformer.

Independent acknowledged international testing laboratory test report should be submitted and the oildelivered shall be accepted only if the international oil analysis laboratory tests results show that the oil

comply with this specification.

Sufficient additional quantity of oil for topping up and making up from transformer and for losses,..etc.Shall be provided and this shall be included in the tender price.

The oil to be supplied under the specified spares shall be supplied in non-returnable steel drums normalcapacity 210 liters.

3.2.27.

TENDER ANALYSIS

For the determination of the successful offer, the cost of the transformers and their annual losses shall

be taken in to account.

The capitalization will be based on the following assumption:

Interest on capital : 10%

Capitalization period : 10 years.

Charge per unit : 0.026 KD/KWH

Loss load factor (LLF) : 0.26

Demand factor (D) : 0.5

Transformers energy : P(Fe) = 8760x iron losses

Iron loss per year.

Transformers energy : P (Cu) = 8760 x (LLF) x (D) x (D) x copper loss.

Copper loss per year

Total energy loss : P (Fe) + P (cu)

Capitalized operational : 6.14 x { P (Fe) + P (Cu) }

X charge per unit.

The transformer shall be dispatched with the tank filled with an approved make of insulating oil.


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If the acceptance tests of the transformers show that the actual losses exceed the values stated in the

Schedules of Particulars and Guarantees, the excess total energy loss will be capitalized according to

the above assumption and the sum thus obtained deducted from the money due to the contractor as a

penalty. For this purpose, no tolerance will be allowed on the figures stated in the schedule of

particulars and guarantees. At any rate, the actual measured losses should not exceed the figuresstated in the schedules of particulars and guarantees by more than the tolerances stated in the relevant

IEC recommendations.

3.3 LOW VOLTAGE DISTRIBUTION BOARDS:

3.3.1.

Standard:

Low voltage distribution board shall comply with this specification and with IEC/439 or BS/5486.

Each L.V. distribution board shall be straight in line three sections, open type (i.e. without enclosure)

and shall be provided with two nos. of insulated rods for operating the isolators. These operating rodsand any other operating handles that might be required, shall be arranged for mounting on the

switchboard in a suitable manner.

3.3.2.

Rating:

All equipment, busbars, isolators, etc. and all components parts shall be adequately derated forcontinuous full current rating at Kuwaits worst temperature conditions. All ratings referred to in this

specification shall mean maximum continuous current rating under Kuwaits worst temperatureconditions.

3.3.3.

Arrangement of Equipment:

Each switchboard shall comprise, when viewed from the front reading from left to right, as follows:

Section 1:

Way Nos. 1,2,3,4,5 & 6 : 500 Amps feeder control fuse way

Transformer No. 1. : 1600 Amps transformer control and

Instrument panel.Section 2:

Busbar section isolator : 1600 Amps busbar section isolator.

Section 3:

Transformer No. 2 : 1600 Amps transformer control andInstrument panel.

Way Nos. 7,8,9,10,11 & 12 : 500 Amps feeder control fuse ways.

Details of Busbars:

Main : 3 copper busbars rated 1600 Amps.

Neutral : Copper busbar rated 800 Amps.

Earth : Copper bar of adequate size (not less than the

size of neutral busbar).


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The switchboard shall also be provided with suitable base channel work in addition to the fixing

arrangements to the substation brick walls, so that the base channel work may also be fixed to thefloor in the 14 cms. offset available between the wall and the L.T. cable trench by means of rag bolts.

This is to relieve the load on the walls. The feeder and transformer cable terminals after fixing theswitchboard, should be clear off the inside wall of the trench so that incoming cables will be straight.

The switchboards shall be arranged for bottom entry of cables. The boards shall also be arranged for

easy connection of the cables from the front of the board. Due to space limitations the length anddepth of the boards shall not exceed 4.5 meter and 1.0 meter respectively.

3.3.4.

Transformer Control:

Each transformer control panel shall comprise the following:

1 No. 3 single pole air break, pole operated off load isolator rated 1600 amps, continuous rating atKuwaits worst temperature conditions and complying with IEC 408 or BS 5419.

The isolator contacts shall be robust clamp type and shall not depend on the natural spring of thecontacts. Details shall be subject to Purchasers approval. Spring assisted contacts will not be

accepted.

The isolator shall be capable of carrying through 3-phase symmetrical short circuit fault of not less

than 50KA for 0.5 seconds. Evidence to this effect shall be submitted with each and every offer in the

form of a test certificate.

3 Nos. Bar primary type current transformers with ratio 2000/5 amps or 2000/1 amps. class 3

accuracy to BSS 3938 suitable for instruments. The C.Ts shall have adequate VA capacity but thisshould not be less than 5 VA.

6 Nos. Copper connecting bars (2 bars per phase) for connecting the cable lugs to the isolator

terminals. These bars should be fully rated (i.e. each bar rating shall not be less than 800 amps. UnderKuwaits worst temperature conditions). These bars shall have suitable terminal arrangements for

connections to the cable compression lugs for the specified cables below and shall be complete withbolts, nuts and washers. When the above bars are connected directly to the isolator terminals theyshall have suitable intermediate supports to reduce the transmission of stress to the isolator terminalswhen bolting or unbolting the cable lugs to these boards. The size of the connecting bars shall not be

less than (80 x 10 mms).

The length and arrangement of these bars shall be that the cable terminations are below the neutral

busbar level with provision for easy and safe connection of the cables from the front of the boardwith the busbars being alive. Full details shall be submitted with the offer.

Clearances between the live conductors and between the conductors and earth with the cable lugs

connected shall not be less than 25 mm. Cable clamps suitable for clamping 1000 volts single core

cable 800 sq. mm. stranded copper conductor cross linked polyethylene insulated and extruded PVC

served cable. The clamps shall be of non-magnetic metal. The distance between the clamps and theconnecting terminal shall not be less than 500 mm.

3 Nos. Moving iron ammeters suitably calibrated for the above C.T.s ratio and fitted with

maximum demand indicator of the thermal type with 15 or 20 minutes delay.

1 No. 96 mm dial, moving iron voltmeter scaled (0-300) volts.

1 No. Voltage selector switch arranged to select phase to neutrally voltage.


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1 set. Phase fuses and neutral link for instrument service (i.e. voltmeter).

1 set. Three single pole 63 amps. HRC cutouts and one single pole 63 amps neutral link for

substation services.

The instruments shall be suitable located so as not to impede any jointing works. However, the height

of the instrument panel shall be within the convenient reach of the operator.

3.3.5.

Feeder Control Fuse-Way Units:

Comprising 500 amps. 3-phase, 4-wire fuse units, each fuse-way shall be arranged to accommodateand to be complete with the following:

3 Nos. Fuse bases, complying with BSS 88 part 2, with not less than 500 amps. continuous ratingunder Kuwaits worst temperature conditions.

3 Nos. 355 amps (Kuwait Rating) HRC fuses, fitted with fully shrouded grip insulated andunbreakable fuse handle (fuse carrier). The fuses shall be type I as indicated in the attached drawing

No. MC/7/189-D.

The fuses shall be slotted tag type having 92 mm centers as indicated on the drawing. The fusehandles (fuse carriers) shall be provided with fully insulated thumb screw wedge tightening device.Fuse carriers shall be made of unbreakable material. The fuse/fuse carriers shall be adequately rated

to work satisfactorily at 55 centigrade ambient temperature.

3 Nos. Aluminium connecting bars for connecting the cable lugs to fuse bases. These bars shall be

fully rated (not less than 500 amps. Continuous rating under Kuwaits worst temperature conditions).The bars shall be isolated by PVC tubing for safety purpose. These bars shall have bimetallicterminal arrangement at the fuse terminal. The copper layer of the bimetallic arrangements shall not

be less than 1 mm. thick. The bimetallic arrangement shall be permanently secured type and shall be

subject to the Purchasers approval.The above bars shall have suitable intermediate supports to reduce the transmission of stresses to the

fuse bases when bolting or unbolting the cable lugs on to these bars. The size of these aluminium

connecting bars shall not be less than (40x10mms).

The length and arrangement of these bars shall be such that the cable terminations are below the

neutral busbar level with provision for easy and safe connecting of the cables from the front of the

board with the busbars being alive. Full details shall be submitted with the offer and the arrangementof the bimetallic connection should be indicated.

The clearance between the live conductors and between the conductor and earth with the cable lugsconnected shall not be less than 25 mm. We shall be using cable lugs having a palm width of about

55 mm. All the bars shall be colour coded according to R.Y.B. phases.

1 No. Compression type cable gland made of brass type CW75S for receiving 1000 Volts, 4-core

cable, 300 sq.mm. Aluminum conductor insulated with cross-linked polyethylene (XLPE) and steelwire armored and overall sheathed with an extruded PVC sheath. This gland shall be applied on thearmour wire and on the switchboard frame to maintain wire armour earthing. The compression glandshall efficiently maintain the connection between the armour wires and earth bar via suitable

arrangement. Details and final arrangement of the above connecting bars, bi-metallic connection

arrangement and cable glands shall be subject to the approval of the Purchaser. Cable glands shallfully comply with BSS 6121 part 1.The distance between the outgoing feeder terminals and the cable

gland shall not be less than 500 mms.


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Each feeder control fuse way unit shall be provided with three (3) Nos. 300 sq. mm. Aluminium

Cable Lugs and one (1) No. 185 sq. mm Aluminium Cable Lug suitable for BICC - UK or CEMBRE

Italy, crimping tools available with (MEW) complete with the necessary bolts, washers and nuts.

Each feeder control fuse way unit shall be provided with a name plate consisting of 10 cms x 10 cmsnon-metal picture frame fitted with a drop in trifoliate circuit label (laminated white ground with

black letter).

The labels will be engraved by the Purchaser locally. Alternative circuit label arrangement can be

proposed subject to the approval of the Purchaser.

In order to facilitate live jointing, permanent or removable insulated screens in between the outgoing

feeder terminals shall be provided. Proposed arrangement shall be subject to the Purchasersapproval.

The center to center distance between two single core cables of each phase shall be minimum 100

mms.

The center to center distance between two single core cables of adjacent phases shall be minimum150 mms. The center to center distance between adjacent feeder ways shall be minimum 180 mms.

3.3.6

Bus-bar Section Isolator:

3-single pole, air-break, pole operated, off-load isolator rated 1600 amps. Continuous rating atKuwaits worst temperature conditions and complying with BSS 5419.

The isolator contacts shall be of robust clamp type and shall not depend on the natural spring of the

contacts. Details shall be subject to the Purchasers approval. Spring assisted contacts will not be

accepted.

The isolators shall be capable of carrying through 3-phase symmetrical short circuit fault of not lessthan 50 KA for 0.5 seconds. Evidence to this effect shall be submitted with every offer in the form of

a test certificate.

3.3.7

Bus-bars:

The busbars shall be electrolytic hard drawn copper and in accordance with BSS 159.

3-phase 1600 amps. Busbars arranged RED, YELLOW and BLUE from top to bottom and 1 (one)

neutral busbar 800 amps. Located at the lower section of the switchboard such that the neutralconductors of outgoing and incoming cables may be directly connected to this bar. The neutralbusbar shall be complete with suitable bimetallic arrangement to receive the outgoing cables. It shall

also be complete with 2 Nos. 800 amps disconnecting links at the neutral bar ends to allow

connection of the bar to earth bar. For all busbars tapering is not accepted.

Full details and final arrangement of busbars including bimetallic arrangement and disconnection

links shall be subject to the approval of the Purchaser. All copper busbars including the holes and

edges shall be tinned in an approved manner to a minimum thickness of 10 micro-meter as per BS1872, table 1.

Suitable means shall be provided at each sides of the bus-bar to facilitate two separate connection of:1.

Diesel Generators (in case of emergencies).2.

Capacitor bank.

In any case the size of the busbar shall be as follows:

3-phase busbars : 120 x 10 mms minimum

Neutral busbar : 60 x 10 mms minimum


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Earth bar : 60 x 10 mms minimum

3.3.8

Fuses:

The HRC fuses shall be from recognized manufacturer and shall fully comply with B.S. 88, part 5,

1988 unless otherwise specified. The fuse elements of all fuse links shall be from PURE SILVER OR

SILVER PLATED COPPER, Copper fuse elements shall be rejected.

The outer and inner caps shall be made from copper or brass and where necessary electro-tinned. The

body shall be from high quality ceramic capable of with standing high thermal, mechanical andelectrical shocks. Each tenderer shall submit full details of the fuses offered.

The HRC fuses shall also comply with the dimensions indicated on the drawing attached with thetender documents and shall be within accepted tolerances.

All fuses shall be of cartridge type and shall be suitable for erection on 415 volts and shall have

minimum rated breaking capacity of 80 kilo amps. These fuses shall generally comply with a fusingfactor of class Q1 as specified in B.S. 88, part 5, 1980. Each tenderer shall take into full consideration

the higher ambient temperatures of the site in determining the actual rating of the fuses offered. The

tags of all cartridge fuses shall be indelibly stamped (MEW) in 5 mm high letters, in addition to thestandard markings on the fuse links as per B.S. 88, part I. the fuses shall be indelibly marked with

355 Amps Kuwait Rating. Stickers and labels will not be accepted. The 355 amps (Kuwait Rating)

H.R.C. fuses shall be slotted tag type as indicated in drawing No. MC/7/189-D. Each tenderer shallsubmit full and complete details and in particular the following information:-

3.3.8.1

Drawings showing the dimensions of the fuses to be supplied.

3.3.8.2

The current characteristic curves for the fuses supplemented with information on I

sq. t values for pre-arcing and total operating time.

3.3.8.3

The ASTA/KEMA/CESI, or equivalent certificates from the Internationally

Recognized Testing authority for the fuse offered. (Detailed test results are to besubmitted).

3.3.8.4

A confirmation that the time/current characteristics of each fuse complies with the

standard time/current zones as per clause 5.61.3 of B.S. 88, part 5, is to be

submitted.

3.3.8.5

The fuses are subject to inspection by an inspector appointed by (MEW). The

following tests as per B.S. 88 shall be carried out satisfactorily in the presence of our

appointed inspectors for each rating in order to verify the values quoted by themanufacturer.

3.3.8.6

Measurement of power dissipation of the fuse link.

3.3.8.7

Time/current characteristics.

3.3.8.8 Verification of I sq. t. characteristics.

355 amps. (Kuwait Rating) fuses shall be from the original manufacturer and shall not be

manufactured under license.


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3.4 BATTERIES AND CHARGING EQUIPMENT:

50 volts self-contained switch tripping alkaline battery equipment tropically rated and each

comprising:

3.4.1.

50 volts 10 amp hour nickel cadmium alkaline batterybuilt up of 44 cells. The cells shallpreferably be assembled in four 9 cells and one 8 cells blocks complete with intercell

connections and the batteries dispatched filled with electrolyte, discharged and complete

with all necessary maintenance tools and equipment.

3.4.2.

One floor standing sheet steel tripping equipment cubicle having dimensions about 115cms high, 75 cms wide x 45 cms deep arranged to accommodate the above batteries in such a

way as to give maximum clearance for cables. The unit should be arranged for connectionsto a 200/260 volts, 50 cycles, single phase supply and have a quick charge output of one

ampere at a voltage range of 55/77 volts and an alternative low rate output of 10/33 milli-amps at 55/65 volts. Alternatively, a constant potential charging system may be offered. The

battery charger should be provided with A/C supply cords of 3 mt long x 2.5 sq.mm. copper

cable and 13 Amp. Power plug of an approved brand.

The battery/charger housing is to be made from a steel plate 2 mm. thick based on a suitablebase to lift it above the ground by a suitable height. It shall be equipped by suitable upper

and lower vents on the front and side covers. Upper vents for the control unit and the lower

vents for the battery cells chamber. Complete separation between batteries and charger shallbe provided The control unit is to be fixed properly on its base. The front cover shall beopenable door provided with hinges and a ball hinge locking device. The covers shall be

fixed using bolts and nut sets, self screws are not acceptable. The incoming and out going

wiring shall be through brass cable glands type CW to BS 6121 part 1 placed on both rightand left upper sides of the battery charger.

The equipment should be tropically rated for maximum ambient temperature of 550

centigrade and finished in dark grey to B.S. 381 C, colour 632, unless otherwise approved.

All the internal wiring provided must work satisfactorily at the prevailing ambienttemperature and the wires are to be insulated with PVC (type 5 to table 1) as per BS:6746.

Switching arrangements for rectifier control should be as follows :

Double pole A/C input fuses.

Double wound air-cooled transformer with tap. For operation from a 200/260 volts supply.

Three tappings for 210 volts, 230 volts and 250 volts shall be provided. Each tapping shall

be suitable for 10 V of the voltage for which the tapping is designed. Alternativelystabilized A.C. input voltage control may be offered.

Mains indicator circuit.

One full wave bridge connected silicon or selenium rectifier, other type of rectifier will not

be accepted.

Double pole rectifier output fuses.

(X) one variable high rate charging resistance.

One 70 mm dial, 50 mA. Flush mounting moving coil ammeter for low rate charging.

One 70 mm dial, 2 Amps. Flush mounting moving coil ammeter for high rate charging.

(X) one fixed low rate charging resistance.


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One 70 mm dial, 10 Amps. flush mounting moving coil test ammeter complete with test

switch and loading resistance.

The outgoing circuits comprising should be as follows :

One pair cartridge fuses and terminal for telephone circuit 2 Amps.

One pair terminals only for switch tripping.

NB:- (X) These items apply for two rates charging system. In addition to the manual high rate andlow rate charging controls the charger unit shall also be equipped with an automatic charging

system comprising of transistorized circuit with auto/manual select switch. Normally the charger

shall be set on auto. Motorized automatic charging control will not be accepted. Full technical details

of the automatic charging system together with circuit diagram shall be provided with each and everyoffer.

3.4.3.

Drawings and Instruction Manuals:

Fully dimensioned drawings of the offered equipment shall be submitted with the offer. Also circuit

diagram for the automatic charging equipment with full technical details to describe the equipmentand its operation (all in the English language) shall be submitted.

The successful tenderer shall submit all drawings (including wiring and schematic diagram) for theapproval of the Purchaser before the beginning of the manufacture.

3.4.4.

Automatic Charging Control:

When battery charger selection switch is set on auto position the charger must start charging

batteries at high rate, if so the required and shift to low rate charging as soon as the batteries arefully charged, irrespective of time.

The above must be confirmed by the manufacturer and the tenderer in their offers:

3.5

11 KV 3 CORE 300 SQ. MM. XLPE INSULATED CABLE:

3.5.1.

Conductor:The conductor shall be stranded and shall consist of annealed copper having conductivity not less

than 100% international standard. The conductor shall comply with BSS No. 6360. The surface of

individual strands shall be smooth and clean before insulation is applied. The cross sectional area ofeach core should not be less than 300 sq. mm. The cable shall fully comply with IEC 502.

3.5.2.

Insulation:

The insulation shall be cross linked polyethylene applied by an extrusion process and shall complywith IEC 502. The insulation shall be free from any contaminants larger than 0.25 mm in its largestdimension or porosities or voids larger than 0.13 mm. The maximum number of voids between 0.05

mm and 0.13 mm allowed shall be 30 voids per cubic inch of insulation. In plant repairs of the

insulation are prohibited unless specifically agreed to by the Purchaser.

3.5.3.

Screening:

A semi-conducting screen shall be extruded over the conductor. This layer shall consist of black

semi-conducting thermoplastic or thermosetting material and shall be easily removable from the

conductor. The layer shall have an average thickness of 0.38 mm when measured over top of the

strands and shall be cylindrical. A similar semi-conducting screen shall be extruded over theinsulation. This layer shall also be easily removal from the insulation without scratching the surface.


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3.5.4.

Laying up and Bedding:

The 3 cores shall be laid up together with suitable fillers.

The bedding shall consist of at least two layers of a suitable semi-conducting tape, or an extruded

layer of semi-conducting material.

3.5.5.

Current Rating:

The current ratings of cables for the site and installation conditions (refer to substation layout

drawing) shall be stated. This should be based on maximum conductor temperature in normaloperating conditions not exceeding 90 deg. C.

Where ratings as specified for only standard conditions, appropriate adjustments factors should bestated.

3.5.6.

Armour:

The cables shall be armoured with galvanized steel wires to give it mechanical strength and also acts

as a low resistance earth return conductor. Electrical contact shall be maintained between the corescreens and the earthed armour through the conductive bedding.

3.5.7.

Oversheath:

The cable shall have an overall extruded sheath of PVC (type 9 table 1) to B.S. 6746 suitable for use

in the above mentioned site conditions.N.B : The outersheath of cables shall have marking by embossing or indenting "MEW" along with

the manufacturers name with upright block letters of minimum 3 mm height at every two (2)

meters of their length .

3.5.8.

Short Circuit Rating:

The cable shall carry without damages or undue stress a fault current of 31.5 KA. For 1.25 sec. After

a continuous period of full load. It is assumed that the conductor is at its maximum operatingtemperature of 90 deg. C. before the occurrence of short circuit, and the maximum conductor

temperature after the fault duration of 1.25 sec. Mentioned above, will be 250 deg. C. Under these

conditions the cable shall carry the above short circuit currents without damage or undue stress.

Full details to cover the above requirements shall be submitted with the offer.

3.6

600/1000 V SINGLE CORE 800 SQ. MM. XLPE INSULATED NON-COMPACTED CABLES:

3.6.1.

Conductor:

The conductor shall be stranded and shall consist of annealed copper having a conductivity not less

than 100% international standard. The conductor shall comply with BSS No. 6360. The surface of

individual strands shall be smooth and clean before insulation is applied. The cross sectional area ofeach core should not be less than 800 sq. mm. The cable shall fully comply with IEC 502.

3.6.2.

Insulation:

The insulation shall be cross linked polyethylene applied by an extrusion process and shall comply

with IEC 502. The insulation shall be free from any contaminants larger than 0.25 mm in its largest

dimension or porosities or voids between 0.05 mm. and 0.13 mm. The maximum number of voidsbetween 0.05 mm and 0.13 mm allowed shall be 30 voids per cubic inch of insulation. In plant

repairs of the insulation are prohibited unless specifically agreed to by the Purchaser.

3.6.3.

Oversheath:

The oversheath shall be PVC. The PVC shall be of the heat resisting hard type and shall comply with

BSS.6746 (Table 1, type 9).


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N.B : The outersheath of cables shall have marking by embossing or indenting "MEW" along with

the manufacturers name with upright block letters of minimum 3 mm height at every two (2)

meters of their length .

3.6.4.

Current Rating:

The current ratings of cables for the site and installation conditions (refer to substation layout

drawing) shall be stated. These should be based on maximum conductor temperature in normaloperating conditions not exceeding 90 degree C.

Where ratings are specified for only standard conditions, appropriate adjustment factors should bestated.

3.6.5.

Short Circuit Rating:

Offers should be accompanied with short circuit current curves. It is assumed that the conductor is at

its maximum operating temperature of 90 degree. C. before the occurrence of short circuit and the

maximum conductor temperature after a fault duration of 0.5 seconds will be 250 degree C. Thecables shall carry the above short circuit currents without damage or undue stresses.

The formula used in evaluating the short circuit currents should be stated and this shall be supported

with relevant standard.

Full details to cover all the above requirements shall be submitted with the offer.

3.7.

Earthing System:

Each substation shall have an efficient earthing system consisting of sets of four (4) Nos. 1.5 metersx 19 mm dia. Copper bonded earth rods (to make a 6 meters. long rod) located at each of the four

corners of the substation in case of two transformers ring main substations and additional two Nos.

earth points for the four transformers ring main substations and it will be indicated on site by the

Engineer and driven inside the earth pit to depth of 6 meters at each point and connected to eachother, by a copper bar not less than 25 x 3 mm. to form a ring bus as detailed in the attached

drawings No. MC/7/380-B/1 and MC/7/380-B/2. The ring bus and all connections to this bus should

be buried to a depth of at least one meter. The earth pits are to be inside pre-cast hand holes of 30

cm. x 30 cm. opening and a depth of 30 cm. provided with a hinged cast iron cover to enable easychecking of the connection and measurement of the earth resistance.

The contract price shall include all necessary excavation and backfilling of the trenches for theearthing system.

All copper earth bars shall be tinned and all connections and joints on the earthing system shall besoldered, tinned and taped in an approved manner. Disconnection link shall be provided at each earth

pit, so as to facilitate individual measurement of each earth electrode. The resistance of each earthelectrode must not exceed two (2) ohms and the total resistance of the earthing must not exceed one(1) ohm. Connections to this ring shall be as follows:

3.7.1

Each switchgear shall be provided with a copper Earth bar of section area not less than 30 x

5 mm and its associated control and relay boards with an earth bar of not less than 25 x 3mm. All metal parts of these boards other than the live parts shall be connected to the earth

bar by conductors of not less than 2.5 sq. mm. cross section area. Where secondary wiring in

the switchgear is to be earthed, it shall be done at an accessible place in each panel through a

copper link connected to the earth bar. The earth bars of the switchgear shall be connected to

the stations earthing ring at two (2) places in an approved manner.

Similarly, all the transformers, low voltage boards and all indoor equipment shall be

connected to the stations earthing system in an approved manner.


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3.7.2

Each transformer shall be connected to this ring by means of copper bars not less than 25 x 3

mm. The transformers shall be bonded together by similar bars.

3.7.3

The earth busbar of the LV distribution board shall be connected to this ring by a fully

insulated bar or cable not less than 240 sq. mm. (insulated for 1000 volts) which shall be

included in the contract price.

3.8.

Small Wiring:

All control wiring shall have a cross sectional area of not less than 2.5 sq. mm. and shall be

600/1000 volts, insulated with type 5 PVC table I of BS. 6746, stranded copper conductors. All

control wiring shall be suitably terminated and fitted with identification ferrules and marked with

circuit numbers in accordance with BRITISH CENTRAL ELECTRICITY AUTHORITY

ENGINEERING RECOMMENDATIONS S-12 standard numbers for small wiring or similar

approved standard.

The trip circuit shall have an additional ferrule coloured red and marked trip.

All terminal blocks shall be from an approved design and all exposed terminals shall be enclosed by

detachable covers. The trip circuit cables shall be coloured black and the instrument transformercables (C.Ts and V.Ts) coloured with their respective phase colours. Alternatively, all small wiring

can be uniform colour (e.g grey) but instrument transformer cables shall have additional coloured

ferrules at both ends of each conductor run (in accordance with their phase colours). The wiring of

the auxiliary circuits shall be segregated from the main circuit by heat resistant tubes made of

insulating material covered by earthed metallic partitions. Terminal blocks, small wiring

terminations, ferrules and wire numbering and colouring shall be subject to the approval of the

Purchaser.

3.9.

Labels and Secondary Fuses:

Each panel of each switchboard shall have a circuit label of adequate dimensions, mounted on the

front of the panel at a prominent position. These labels shall be made of suitable and approved

engraving material approximately 2 mm. thick having white surface with black engraving. The labels

shall be mounted in rigid frames and arranged for easy insertion and withdrawal. Labels of similar

material and specification shall also be fixed on the rear of each panel.

Alternative design of labels can be proposed by the contractor subject to Purchasers approval.

All other labels shall be similar material and engraved in English. Full details and locations of all

labels shall be indicated on the drawings and shall be subject to approval of the Purchaser.

All necessary fuses and links shall be supplied and these shall be fitted with clearly legible labels

indicating the circuit and shall be grouped according to their functions to facilitate indication. Fuselabels shall indicate the current rating of the fuses and code symbols shall correspond with the

diagrams. All secondary fuses shall be cartridge type in accordance with the Purchasers standard

types shown on the drawings attached to these specifications.

Alternatively, tenderers may offer miniature circuit breakers instead of fuses for the secondary

circuits of the switchboards. Full details of these shall be submitted with the tender and shall be

subject to the approval of the Purchaser. Two spare miniature circuit breakers of each type shall be

supplied with each substation and shall be included in the contract price.


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3.10.

Locks and Pad-locks:

Locks and pad-locks of high class materials suitable for weather in Kuwait, especially the sandstorms shall be supplied for each circuit breaker operating cubicles and for all other outdoor

equipment which need locking facilities.

Locking arrangement shall be in accordance with the best modern practice, and the contractorsdrawings submitted for approval of the Purchaser, should indicate the various points on theequipment at which locking arrangement will be provided.

Two individual keys for each lock or pad lock shall be provided. Master keys shall be supplied in

addition to above. Twelve (12) master keys of each type shall be supplied. The types of master keys

should not exceed two.

3.11.

TESTS :

The contractor shall carry out the tests specified by any applicable IEC/British Standard

Specification, unless otherwise agreed upon and such additional tests in the contractors works as inthe opinion of the Purchaser or his representative are necessary to determine that the works comply

with the conditions of these specification.

All tests shall be carried out in the presence of and to the satisfaction of the Purchaser or his

representative and at such times as he may reasonably require.

All instruments used for testing purposes, shall if required by the Engineer be calibrated by an

approved authority.

The cost of all tests shall be included in the contract price and shall not be quoted for separately.

All type tests shall be done at an independent acknowledged international testing laboratory

(ASTA/KEMA/CESI ), and all tests to be done at the laboratory origin country, while tests

done in other lab and witnessed by one of the above approved independent acknowledged

international testing laboratory will not be accepted

3.11.1

11 KV Switchgear

3.11.1.1 Routine Tests :

All routine tests shall be carried out in accordance with the relevant IEC/B.S. Standards, including :

a)

Operational tests for circuit breakers and isolators.

b) Millivolt drop test across circuit breakers contacts and between terminals.c) Power frequency high voltage test.

3.11.1.2. Type Tests :

All Type tests shall be carried out in accordance with the relevant IEC/B.S. Standards.

a.

Mechanical performance test; the operating mechanism shall be in service during this test.

b.

T

11 kv switchgear 31.5ka

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