LV Distribution Fuse Board (Feeder Pillar) Kahramaa specification

Specification for LV Distribution Fuse Board (Feeder Pillar)

EP-MS-P4/S2-010

EP-MS-P4/S2-010

Specification for LV Distribution Fuse Board (Feeder Pillar)

Issue : 2

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Specification for LV Distribution Fuse Board (Feeder Pillar)

EP-MS-P4/S2-010

Document Control Department

Document Type

Document Title

EP

Material Specification Standards

EP-MS-P4/S2-010 Specification for LV Distribution Fuse Board (Feeder Pillar)

Issue Approval Prepared By

Approved By

Consultant M/s. Ewbank Preece Limited

Head of Design & Development

Member of the Mott Mac Donald Group,UK

Manager, EN Planning Dept.

Material Standards & Specification Engineer Signature:

Signature:

Issue Record Issue No.

Date

Reason for re-issuing Document

0.0

30.04.2003

First issue of Materials Specification Standards

1.0 2.0

02.10.2008

Review of Materials Specification Standards

26.01.2012

Review of Materials Specification Standards

3.0 4.0 5.0

Key Words

:

Specification for LV Distribution Fuse Board (Feeder Pillar)

Review Frequency

:

Every 3 years

When this document is approved for publishing on the intranet, a copy of its Document Control page should be sent to the QA section who is custodian of KM quality management system.

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Specification for LV Distribution Fuse Board (Feeder Pillar)

1.0

EP-MS-P4/S2-010

Scope This specification details about requirements for design, manufacture testing, packing, transport and supply of LV Distribution Fuse Boards for use in Outdoor Sub-stations for 11 kV Distribution Networks for which supply low voltage, with separate neutral and earth in the state of Qatar a)

Pillar mounted fuse boards, cable connected, subsequently referred to as FEEDER PILLARS.

b)

Transformer mounted fuse boards in cabinets, subsequently referred to as FUSE CABINETS.

The fuse boards are for use on 3 Phase, 4 wire AC systems at a frequency of 50Hz and at a nominal voltage of 415 V between phases. 1.1

REFERENCES This Standard makes reference to, or should be read in conjunction with, the following documents :

Issue : 2

IEC 60269/BS 88-5

Cartridge Fuses for Voltages up to and including 1000V AC and 1500V DC, Part 1, General Requirements.

IEC 60439/1 & 5

Low-Voltage Switchgear and Control Gear Assemblies.

BS 381C

Specification for Colours for Identification, Coding, and Special Purposes.

IEC 60269/BS 1361

Cartridge Fuses for AC Circuits in Domestic and Similar Premises.

BS 1363

13A Plugs, Switched and Unswitched Socket-outlets and Boxes.

BS EN 22063:1994

Metallic and other inorganic coating.

BS 3382

Thermal spraying. Zinc, Aluminium and their alloys. Electroplated Coatings on Threaded Components.

ISO 272/4759/BS 3692

ISO Metric Precision Coatings on Threaded Components.

IEC 60044-1(1996)/ BS 7626:1993

Current Transformers.

ISO 885/ISO 4759/1

ISO Metric Black Hexagonal Bolts, Screws and Nuts.

BS 6001

Sampling Procedures and Tables for Inspection by Attribute.

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Specification for LV Distribution Fuse Board (Feeder Pillar)

EP-MS-P4/S2-010

BS 6231:1998

Specification for PVC Insulated Cables for Switchgear and Control Gear Wiring.

BS 6480/IEC 60055

Impregnated Paper Insulated Cables for Electricity Supply.

IEC 60076

Power Transformers

BS 2562:1993

Specification for Cable Boxes for Transformer and Reactors.

2.0

ENVIRONMENTAL CONDITIONS The LV Distribution Boards will generally be installed in outdoor situations in a tropical climate having the following characteristics: 1.

Altitude:

Low lying, generally close to sea level - no point exceeding 100 metres above sea level.

2.

Temperature: Air maximum 50°C (460 C typical) Air minimum 0°C (100C typical) Air maximum mean average 45°C Air minimum mean average 10°C Exposed sunlight 75°C maximum.

3.0

3.

Solar Radiation Peak 1030W/sq.m.

4.

Humidity:

Ranges between 30% and 100%, though 100% is common throughout the year and may occur at air temperatures in excess of 30°C.

THE LOW VOLTAGE DISTRIBUTION BOARD (FEEDER PILLAR) 1.

General Design & Constructional Features

3.1.1 This Standard covers arrangements of feeder pillars, as described below, suitable for use with: a) b)

500, 800, and 1000 kVA Transformers 1250 and 1600 kVA Transformers.

3.1.2 Transformers are oil filled and in general accordance with IEC 60076. LV Interfaces are generally in accordance with BS 2562, specific detail being provided in this Specification. 3.1.3 The feeder pillars shall be complete with supporting members as required on which shall be mounted control equipment, busbars and instrumentation in accordance with the arrangements specified below. The design shall be such that the cables can be readily jointed from the front. 3.1.4 All parts of the distribution equipment shall, as far as practicable, be readily accessible and replaceable without excessive dismantling.

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3.1.5 Insulating materials shall be as nearly non-hygroscopic, resistant to tracking and self-extinguishing as present good manufacturing technique permits. 3.1.6 All metallic parts including (but not limited to) bolts, nuts, washers, hinges latches shall be of stainless steel material. Where live metal work is adjacent to the framework a sheet of bakelite or other suitable low voltage insulating material shall be fixed to the inner side walls of the feeder pillar and shall extend to at least 200mm above the red phase (upper phase) top contacts and an equal distance below the blue phase (lower phase) bottom contact. The width of the insulating sheet shall approximate to that of the side walls of the feeder pillar and the thickness shall not be less than 2.0mm.The sheet of insulating material shall be suitably fixed. The fixing shall not incorporate metallic parts which protrude towards live metalwork. If adhesives are used, the quality shall be such as to ensure proper adhesion under the temperature/humidity levels described earlier. 3.1.7 All parts of equal size and rating shall be inter-changeable. The general design shall be such that the number of joints shall be kept to a minimum. All bolted joints shall be secured by corrosion proof steel bolts. All bolts and studs shall be plated to BS 3382 and shall have corrosion proof locking features. Each distribution unit position shall be drilled for mounting at 145 ± 5 mm centers. 3.1.8 The design & construction shall generally conform to the latest versions of IEC 60439-1 and IEC 60439-5, and Technical specification # 37-2 of Energy Network Association. 3.1.9 The feeder pillars shall be designed to take up the following arrangements: - 2500 A Busbars - 2500 A incoming transformer unit: - Nominal size of incomer cables up to 7 Nos. of 800 sq.mm. - 6 Nos. 630A outgoing distribution units. - Instrument panel. The framework shall be arranged to accommodate the equipment in the following order reading from the front, left to right: Distributor units Transformer unit Instrument panel 3.1.10 The FP shall be constructed only of materials capable of withstanding the mechanical, electrical and thermal stresses as well as the effects of humidity which are likely to be encountered in normal service. The insulating materials used for barriers, and other insulating parts shall have resistance to thermal stress and flame retardant properties in accordance with clause 8.2.102 of IEC 604395. 3.1.11 Protection against corrosion shall be ensured by the use of suitable materials or by the application of equivalent protective coatings to the exposed surface, taking into account of the intended conditions of use and maintenance. The materials of coating shall pass the appropriate tests of clause 8.2.103 of IEC 60439-5. Issue : 2

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3.1.12 The housing of the FP shall be robust construction, and manufactured from sheet steel. Its mechanical properties shall comply with the requirements specified under clause 8.2.101 of IEC 60439-5. 3.1.13 IP protection of FP enclosure shall not be less than be IP 41 in closed door condition. However, adequate ventilation shall be provided to permit natural circulation of air. The ventilation apertures shall be covered with corrosion-proof metallic screens to prevent entry of vermin and other foreign bodies and ingress of water. 3.1.14 Access to the front of the FP cabinet shall be through double leaf triple hinged door, fitted with a locking bar to secure them top and bottom. The locking bar shall be operated by a single robust handle which shall be arranged to permit locking by a padlock with a 52 x 49mm body, 8.5mm diameter shackle, having a clear inside width of 29mm and inside length of 41 to 55mm. The holes provided for the shackle shall be not less than 10mm diameter. For adequate illumination of cabinet, a heavy duty LED lamp with limit switch shall be provided inside the feeder pillar which interlocked with door open/close operation. All gaskets for doors shall be of superior quality and withstand the mentioned climatic conditions. 3.1.15 The FP cabinet shall be designed to ensure that adequate clearances shall be provided to permit closing & locking of main doors, even when the incoming transformer circuit isolator’s blades are fully left in an open or closed position, and pad locked with its protection cover. 3.1.16 The front apron plate, along with any associated structural members, at cable entry point of the cabinet, shall be removable type to facilitate easy installation or reshuffling of outgoing units cables. Rear access to the cabinet shall not be provided. 3.1.17 The design shall be such that cables can be terminated from the front through bottom entry. All Parts of equal size and rating shall be interchangeable. The general design shall be such that the number of joints shall be kept to a minimum. Corrosion proof (with electro-nickel plated) steel bolts shall be used for electrical joints. All bolts and studs shall be plated to BS 3382 and shall be corrosion proof. 3.1.18 Bus-bars shall be situated at the rear of the equipment. Bus-bars shall be made of nickel/tin-plated high conductivity electrolytic copper and un-insulated. There will be sharp edges on the entire bus bar. Phase bus-bars shall be colour marked (at least 25 mm shrinkable insulating tubes) in sequence from top to bottom as red, yellow, blue and the neutral bus-bar shall be marked as black. There shall no mark on the earth bus-bar mounted at the. Earth bus-bar shall be mounted below the bottom plate (not above base plate) and a suitable bolt to be provided for the connection of earthing bus bar to earthing rod. 3.1.19 All metal works including internal steel work shall be securely bonded in a way to ensure perfect connections between the parts, components and earth rod. 3.1.20 A bolted link-bar of same rating as neutral bar, shall be provided between the neutral and earth bus-bars. The metal framework of the fuse cabinet shall be bonded to the earth bar. Issue : 2

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3.1.21 Where live metal is adjacent to the framework a sheet of Bakelite or other suitable low voltage insulating material shall be fixed to the inner side walls of the fuse cabinet. It shall extend to at least 200mm above the red phase (upper phase) top contact and an equal distance below the blue phase (lower phase bottom contact). The thickness of the insulating material shall not be less than 2.0mm. The width of the insulating sheet shall approximate to that of the sidewall of the fuse cabinet. The sheet of the insulating material shall be suitably fixed. The fixing shall not incorporate metallic parts, which protrude towards live metal work. If adhesives are used, the quality shall be such as to ensure proper adhesion under the temperature/humidity conditions stated in this Specification. 3.1.22 Insulated dividing barriers shall be provided between incomer unit, outgoing distributor units and instrument panels. The fixing of the insulated dividing barriers shall be such that they shall not swing. 3.1.23 All CTs should be complied with thermal class insulation ‘ F’. 3.1.24 Two small cable entry holes fitted with M25 brass compression glands, to be made on the bottom plate at right side front corner. This is required to connect auxiliary cables and output cable from REF relay protection. 4.0

Issue : 2

Incomer Unit with Switch-Disconnector (for transformer Control) 4.1

The incomer unit consists of 3 independent single pole switch-disconnectors, each pole independently operated through insulated operating handle. Each pole corresponds to matching phase of the incoming transformer circuit.

4.2

The incomer switch-disconnetor unit shall be a type tested product conforming to the requirements of IEC 60947-3 & IEC 60947-1. It shall be dependent manual operated, with utilization category of AC21A. Making and breaking capacities shall be at least 1.5 times its rated operational current. Product type test certificates, issued from reputed independent laboratory shall be submitted for verification.

4.3

The switch-disconnector contacts shall include a contact-tightening device on both the top fixed contact, the bottom hinged contact, designed to obviate slackening when subject to vibration, and good contact shall not depend upon the neutral spring of the contact. Reasonably good contact shall be made on closing the switch so that the full current can be safely carried in the interval prior to the tightening of the contacts

4.4

The contact tightening device shall be operated by crank action using the insulated operating handle; the same end of the operating handle shall be used for tightening or slackening the contact tightening device as is used for opening or closing the switch-disconnector blades. When the device is being tightened or slackened the operating handle end shall remain in the device. The total movement of the contact tightening device, from full slackness to full tightness, shall not be more than 140° of angular rotation. ISOLATING MOVING BLADES SHOULD REMAIN IN ITS POSITION WITHOUT DROPPING BY ITS OWN WEIGHT, EVEN IN OPEN POSITION.

4.5

Each switch-disconnector pole shall be equipped with transparent polycarbonate safety barrier at front, with pad-locking facilities. Pad-locking shall be possible 26-01-2012

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when the switch contacts are either in fully open or closed positions. When the switch contact blade is in fully opened condition, the blade shall not touch the front safety barrier, and shall have at least 50mm clearance. It shall be possible to close main door of the FP when the contact blade is fully opened and padlocked.

5.0

Issue : 2

4.6

Each phase and neutral of the incomer unit shall be colour marked to correspond with the bus-bars to which they relate.

4.7

The insulated operating handle shall be kept in the slots of clips provided on the framework to store this when not in use. The amount of bare metal on the pole shall be kept to a minimum.

4.8

Each switch-disconnector pole shall be equipped with one current transformer (details specified elsewhere). It shall be possible to easily change current transformers, without dismantling any major components.

4.9

A bolted link of not less than 1250A rating shall be provided to disconnect the neutral.

4.10

Robust and rigid insulated dividing barriers, of not less than 5mm thickness, shall be provided between each pole of incomer unit. The fixing of these insulating dividing barriers shall be such that under normal operating conditions it is not possible for contact to be made between live metalwork of different phases or between live and earthed metalwork.

Outgoing Distributor units 5.1

Each distributor unit shall be drilled for mounting at 145 +5mm centres apart. It shall be possible to change any single bus-bar or cable connection without affecting other phases.

5.2

Contact assemblies shall be supported from the steel frame-work by means of strips, rods, bars or mouldings of insulating materials. The arrangement of supports shall be such that mechanical stresses produced in service by the temperature rise of connections shall not adversely affect the alignment of the contact surfaces.

5.3

The fixed contact assembly shall be suitable for accommodating a fuse carrier with a 92 mm terminal centre fuse-link type 'J' in accordance with BS 88. Fuse carriers shall be supplied with the pillars. Each fuse carrier shall be suitable for inserting in a phase of the unit by hinge action pivoted on the lower contact and for withdrawing by snatch action. The contacts shall be arranged to permit contact tightening and the contact surfaces shall be flat, accurately aligned in pairs and no sharp edges.

5.4

The phase cable side fuse contacts shall be designed with long and short reach and shall be fitted with forward projecting M16 captive steel studs, one per contact complete with a full nut. A lock washer, and plain washer with lock nut shall be provided. The contacts shall be so designed that they provide adequate spacing and are fully interchangeable to permit terminating the phase conductors of a cable whatever their lay.

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5.5

The phase cable side contact groove (for receiving the fuse) shall be centrally and symmetrically placed, so that, even if this contact is fixed in reverse side, its fixing centre shall not miss its alignment for fixing fuses. Further, if these contacts are made in ‘L-shape’, the gap between adjacent contacts, when fitted in reverse directions, shall be at least 60mm. Alternatively, if these contacts are made in ‘I’ shape, these contacts shall be fitted with additional copper spacer rings of 6mm thickness, so that the outgoing cable insulation will not touch the hot bus-bars, when connected.

5.6

Insulated dividing barriers shall be provided between phase contact assemblies and phase and neutral contact assemblies which shall make it impossible to insert a fuse link between contacts of different phases.

5.7

There shall be no separate neutral isolating link on each outgoing unit. The neutral conductor of each cable (of outgoing unit) shall be terminated on to a contact bar, rated at 315A, mounted below the corresponding outgoing distributor unit, between the neutral bus-bar and the insulated support strut. The bottom fixing of the insulated support strut shall be mounted above the neutral contact bar so as to allow the neutral core an unimpeded approach to the desired fixing position. This neutral contact bar shall be drilled in two positions and fitted with a high tensile M16 steel bolt, nut, and lock-washer or plain washer with locknut shall be provided. The neutral bus-bar shall be fitted 460mm above the centre line of cable cleats at bottom.

5.8

Bottom plate of the feeder pillar with cable entry holes, shall be divided into two portions. By removing the front portion, and front apron plate, it shall be suitable to connect, disconnect, or interchange any cable connection. All holes shall be closed with dummy plates which are removable at the time of connections.

5.9

Cable entry holes shall be fitted with suitable sizes of Brass Wiping Glands conforming to BS 2562 size: X and size: Y. Wooden Cleats, if any, provided shall be in addition to the ‘Brass Wiping Glands’. Brass Wiping Glands shall need to ensure that the bending moment coming through the Cable. Laying, shall not be transferred to connecting terminals.

5.10

The cleat shall clamp directly on to the PVC over sheath of the cable. The cable cleat and its fixings shall be adequate to support the outgoing cable in normal service and when subjected to the short circuit duty specified elsewhere.

5.11

Cable termination arrangement shall be suitable for accommodating up to and including 300mm² 4 core stranded copper conductor either paper insulated lead sheathed double steel tape armoured PVC over sheathed cables to BS 6480 or XLPE insulated steel wire armoured PVC over sheath of the cable as per IEC 60502.

5.12

Required number of holes shall be drilled on earth bar and fixed with M16 bolts, nuts & washers, for terminating Cable earths from each out going cable.

5.13

All cable connections shall be suitable for terminating using heat shrinkable materials and crimping lugs. (Heat shrink terminations & cable lugs are not in the scope of supply).

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5.14

Provision shall be made on each outgoing feeder ways to affix and padlock a suitable insulated device to prevent fuse links being installed or removed. Two such devices shall be provided with each feeder pillar. The device shall not obstruct the feeder pillar doors from closing when in position or when stored within the feeder pillar. It is essential that the device can be safely fitted whilst the pillar and each feeder is alive.

5.15

The device shall be marked with the following wording in English and Arabic and be clearly visible when viewed from the front with the feeder pillar doors open: "CAUTION -MEN WORKING - DO NOT INTERFERE WITH THIS APPARATUS”

5.16

6.0

Blank circuit labels suitable for engraving black letter on white background shall be provided for all outgoing circuits. The support for the circuit labels shall not be on any live part.

Electrical Ratings & Characteristics     6.1

Rated operational voltage (Ue) Rated insulation Voltage (Ui) Rated impulse withstand voltage (Uimp) Rated frequency

: 415/240Vac : 690Vac : 8kV : 50 Hz

Restricted Earth Fault (REF) Tripping Mechanism a) The purpose of REF Protection relay is to trip the 11kV side of the Transformer Switch or from the REF scheme on LV side of Transformer, in which CTs are provided in the feeder pillar, which Protect during an earth fault within in the protected zone of the scheme, i.e. LV winding up to the CT location. b) The scheme shall have 4 Nos. of class X CTs (1 for each phase and 1 for neutral) and shall be mounted inside the feeder pillar, The replacement of CT (if needed), shall not affect any of the connection or disconnection on income or outgoing cables and replacement of contacts. c) The secondary of all these CTs shall be connected in parallel (i.e. the same polarity terminals connected together ) for the REF scheme, and shall be connected to electro-mechanical type REF relays (like CAG14 or equivalent approved by KAHRAMAA) through stabilizing resistance of proper rating. d) The REF relay terminals shall be easily accessible for checking on load current and tightness. e) All the CTs used for the REF scheme shall have same ratio, magnetization characteristics, winding resistance, etc.and shall be from same manufacturer. The knee point voltage of CTs must be higher than the stabilization voltage for maximum external fault current.

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f) Current Transformers shall be rated 2500/5 Amp for 2500 Amp rated and 1600/5 for 1600 Amp rated feeder Pillars. g) To achieve stability during external fault, proper short time rated variable stabilizing resistor shall be provided in series with the REF relay. The stabilizing resistor shall be easily accessible and shall be easily replaceable. Same methodology for REF scheme calculation shall be adopted for the above. h) Provision to gland PVC insulated, sheathed and armored 2x 2.5 sq.mm copper cable for Inter tripping shall be used for interconnecting the trip wires from Feeder Pillar to 11kV transformer control switch (in general). i) Terminal Blocks having isolating link and CT shorting facility shall be used at feeder pillar and 11kV switchgear for terminating secondary wires of CTs. The single point earthing of CT secondary circuit shall be confirmed. j) The Trip wires from the REF relay in the feeder pillar shall be terminated on TBs having isolation links. This TBs shall be properly labeled (such as REF int. trip) and shall be provided with proper identification ferrules. k) All wires shall be provided with ferrules for identification. For example, wires at CT terminals shall be ferruled as S1 and S2. l) The scheme shall be tested for, CTs to prove ratio, polarity, magnetization curve and winding resistance, ratio checks for confirming that the installed CTs are adequate for the REF scheme and also the stability checks and Tripping shall be proved. m) Sensitivity of the scheme shall be tested by Primary injection. Also the stability of the scheme shall be tested for external faults (Balancing and unbalancing and the results shall be provided. n) Certification with test results complying above requirements shall be provided with each unit. o) For Intertripping the RMU to operate the shunt coil of RMU 24 V long life battery shall be installed in the feeder pillar and the battery supply shall be connected through the REF relay contact and connected on proper terminals. Location of battery shall be at front top on the feeder pillar within a suitable fabricated lockable box. 6.2

Issue : 2

REF data for 2500 AMP Rated Feeder Pillar Current Transformer Ratio 2500/5 Class X Winding resistance at 75 Degree