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PART IX TECHNICAL SPECIFICATION NO.MEW/SS/9 PPOWER CABLES AND CONTROL CABLES

9. General: The work covered by this specification includes the supply and installation of 132kV, oil-

filled cable feeder tails and power and station transformer cable tails of all voltage levels. The 132kV O/F cable feeder tails shall be supplied in accordance with the specified total

lengths of all circuits. However, the manufacture of these cables shall not be started without first obtaining the written approval of the Purchaser who will decide the cable drum lengths to suit the approved cable routes. Making of road crossings outside the substation boundaries is not part of this specification, however, laying of cables and pulling through these crossings must be included in the offer price. Surplus cables of length of 30metres and above only shall be delivered to MEW Stores by the Contractor. These cables shall be wound on drums and protected against sun rays by battens or other approved method since they will be stored in the open. For oil filled cables the drums shall be complete with oil pressure tanks and pressure gauges to keep the oil pressure inside the cable. Other prices of cables shall be considered as scrap and disposed off by the Contractor.

Regarding transformer cable tails of all voltage levels, the Tenderer shall include in his offer the cost of supply and installation and jointing complete in every respect all necessary cables and accessories for the purpose. Attention of Tenderers is drawn to the fact that the quoted price should be based on the maximum length that may be needed in accordance with the layout arrangement of the substation as finally approved by MEW. If for any reason the approved layout is modified resulting in an increase of the cable lengths, this will not entitle the Contractor for claim for any extras to the contract price. After complete installation of work, any surplus quantities of cables, accessories...etc shall be removed by the Contractor from site(s) and disposed off by carting away to his stores or dump and the cost of such should be included in the offer price.

9.1 Operating Conditions: The cables shall give trouble free service under the worst site conditions (climatic and

soil) encountered in Kuwait and shall carry their rated current continuously under the worst climatic conditions which prevail in summer (see clause 1.4) and the soil conditions mentioned below and shall withstand the maximum fault currents stated in this specification without damage or deterioration.

a. The cables will be exposed to direct rays of the sun at the terminations at the outdoor sealing ends and at the transformers and shunt reactors. They should be capable of withstanding such exposure continuously in service without any deleterious effect on the insulation, sheathing or covering. They should also be suitable for storage in the open for a period at least two years without battens or shuttering. For protection of cables and cable sealing ends where used on power transformers and reactors, sun shielding shall be provided.

b. The cables will be laid partly in ducts or concrete trenches, but where cables are buried in the ground, this should be at a depth of 1.5meters for 132kV cables and 1.4metres for 33kV cables where soil varies from sandy to rock-like gatch compared to dry hard clay, with a corresponding ground thermal resistivity “g” of 120oC cm/watt and a ground temperature varying from 35oC in summer to 15oC in winter. For 11kV and 1kV cables, depth of laying shall be 90 and 75cms respectively.

The soil in Kuwait is very corrosive. Sulphate reducing bacteria is common to all soils in Kuwait areas and as the soil is generally rich in sulphates, the anaerobic conditions which may arise in contact with buried pipes and cables favour the development these anaerobic organisms which generate hydrogen sulphide and consequently render these areas most corrosive.

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In view of the high temperature encountered in Kuwait, it should be stressed that PVC plasticizers should be of long chain high molecular weight type to reduce the loss of plasticizer in the hot and corrosive conditions. This prevents shrinkage of the PVC with subsequent cracking of the film.

Typical analysis of the soil sample is as follows:- Appearance : Wet coarse sand with some

clay Ph value of water in contact with the sands : 10.00 Calcium sulphate as CaCO4 : 25.00% dry basis Calcium carbonate as CaCO3 : 40.00% dry basis Magnesium sulphate MgSO4 : 6.00% dry basis Sodium Chloride as NaCl : 5.00% dry basis Iron as Fe2O3 : 2.00% dry basis Sulphate reducing : Present Moisture : 15.00% N.B. The sand is not corrosive under dry aerated conditions, but under anaerobic

conditions, the sulphate reducing bacteria in the sand will result in serious corrosion of metals in contact with the sand. The cable coverings over the lead sheath as stated in these specifications are designed to combat this. Where PVC (as sheath covering or overall covering) is used, the PVC should be suitable for the soil conditions. Tenderers should confirm in their offers that the PVC will be suitable of these conditions.

9.2 General Specification Applicable to Power Cables: The cables shall have insulation levels to withstand any voltage surges that may occur due

to switching operations, sudden load variations, faults, etc. The cables shall satisfy the requirements of BSS.6480 for paper insulated cables as a minimum and IEC 141-1 & ESI-09-4 standards for oil filled cables and IEC502 & IEC840 for XLPE cables, as well as the requirements of these specifications.

9.2.1 Conductors: The conductors for the 132kV, 33kV & 11kV and 1000 volts single core and 11kV 3 core

cables shall be made from clean and smooth stranded plain annealed high conductivity electrolytic copper wires laid up and shaped into circular cores complying with IEC 228 and BSS 6480. Conductivity should not be less than 100% international not less tan 100% international standard. Oval or sector shaped conductors will not be accepted. Aluminium conductors for these cables will not be accepted.

9.2.2 Insulation: a) The insulation for 132kV 1/C, 33kV 3/C oil filled cables and 33 & 11kV PILC&S shall be

of the best quality wood pulp kraft paper. All PILC&S cables shall be of the mass impregnated non-draining type.

b) The insulation for the 11kV, 3/C and 1/C and 1000volts single core cables shall be hard grade, heat resisting cross linked polythylene (XLPE) applied by an extrusion process. The insulation shall be free from any contaminations larger than 0.25mm in its largest dimensions or perosities or voids larger than 0.13mm. The maximum number of voids between 0.5mm and 0.13mm allowed shall be 30 voids per cubic of insulation. In plant repairs of the insulation are prohibited unless specifically agreed to by the Purchaser.

The XLPE insulation shall be applied by a combined extrusion and vulcanization process and shall form a compact homogenous body.

c) The insulation shall withstand an impulse test voltage of 650kV, 195kV and 95for 132kV, 33kV and 11kV cables respectively.

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9.2.3 Lead Sheath: The sheath where specified shall be of lead alloy ”E” for solid cables conforming to BSS

801. For oil filled cables the sheath shall be either of lead alloy type 1/2C or tellerium allowed lead (Kb-Pb Te 0.04) conforming to DIN 17640. The quality of extrusion shall be of the highest order so as to exclude the possibility of any weakness in the sheath. The sheath for all types of cables should be applied using continuous lead sheath process by using continuous extrusion machines. Extrusion by discontinuous machines will not be accepted. Aluminimum sheathed cables will not be accepted for any type of size of cables.

For the 1000volts cables, the sheath shall be of PVC. The PVC insulation shall be free from foreign materials and defects liable to reduce the electrical strength of the insulation and shall be type 9 (Table 1) of BS 6746. It shall be applied by any extrusion process and shall form a compact homogenous body.

9.2.4 Armour Wires: All armour wires (where specified) shall be galvanized steel to B.S. 1442. Galvanizing

shall be carried out in accordance with BSS 443. Sizes and the numbers of wires shall be stated in the schedules.

9.2.5 Metal Tape Reinforcement: If metal tape reinforcement of lead sheath is specified, this will consist of 2 layers of non-

magnetic material, stainless steel tape or hard copper tape or tin bronze with suitable bedding under the tape reinforcement.

9.2.6 Compound: The compound used shall not melt or run when exposed to the temperature prevailing

during transit or at site in Kuwait during operation. 9.2.7 Serving: The soil in Kuwait is naturally very corrosive and it is essential therefore that the serving

of the cables be designed to prevent corrosion. Reference should be made to operating conditions described in this specification.

9.2.8 Graphite Coating: A thin layer of graphite coating is to be applied to the outer covering to permit electric

tests. 9.2.9 Lime Wash: The lime wash should be such as to prevent adhesion between turns and layers of cables

and between cable and drum at temperature likely to be met with during transit or storage in the open.

9.2.10 Cable Lugs: The cable lugs shall be of copper of the same quality as the conductor. The length of the

above shall not be less than 65mm for 300sq.mm 11kV cables and 120mm for 1000sq.mm 1000volts cables. The lug bore thickness should not be less than 10mm. Dimensioned drawings of the lugs shall be submitted with the offer.

9.3 Details of Power Cables and Pilot Cables: 9.3.1 Oil-Filled 630sq.mm 1/Core 132kV Cables: i) Conductors: The conductors shall be of stranded plain annealed high conductivity copper shaped into

circular cores and shall have a cross-sectional area of 630sq.mm and formed with central oil duct of 12mm diameter.

ii) Conductor Screening: Two layers of semi conducting carbon paper tapes of a total nominal thickness of 0.2mm

shall be applied over each conductor.

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iii) Insulation: The thickness shall not be less than the value corresponding to a peak impulse voltage

level of 650kV and system highest voltage of 145kV, but the minimum thickness shall not be less than 8.5mm.

iv) Core Screening: Two layers of semi-conducting carbon paper tape having a total nominal thickness of

0.2mm shall be applied over each conductor and a metalized paper or non-ferrous metal tape screen shall be applied over the paper insulation and reinforced by a copper woven fabric tape.

v) Sheathing: The cable shall then be drawn either into lead alloy ½ C conforming to BSS 801 or

tellerium alloyed lead (Kb-Pb Te 0.04) conforming to (DIN 17640) and lightly reinforced by means of helically applied tapes. The minimum average thickness shall not be less than 2.5mm and the minimum thickness at any point shall not be less than 2.3mm. The sheath should be applied on the insulated cable using continuous lead sheath process (See clause 9.2.3 above)

vi) Serving & Bedding: The following layers shall be applied over lead alloy sheath: a. Coating of water proof insulating compound. b. Suitable bedding and metal tape reinforcement which shall consist of two layers of non-

magnetic material (tin, bronze, stainless steel or hard copper tapes) and further served as follows:-

c. Outer covering of extruded Black PVC jacket of minimum average thickness at any point not less than the values given in table 1 below. The PVC shall conform to BSS 6746 and shall fulfill the test requirements for PVC type 9 of table 3 of BSS 6746 as minimum and shall be suitable for site conditions stated under clause 9.1.

The PVC sheath shall be embossed with voltage designation (132kV) and the cross-section area of conductor and the manufacturer’s name and year of manufacture and with same manner described in BSS.6480 and ESI standard 09-4.

Tenderers should submit with their offers a guarantee for the suitability of the PVC to the site condition mentioned in this specification .

d. Graphite coating. e. Overall lime water.

Table Calculated diameter under oversheath

Minimum average Thickness

Minimum thickness at any point

Above mm Upto and including mm

mm Mm

25 30 2 1.6 30 35 2.2 1.77 35 40 2.4 1.94 40 45 2.6 2.11 45 50 2.8 2.28 50 52.5 3.0 2.45 62.5 77.5 3.3 2.71 77.5 -- 3.6 2.96

9.3.2 XLPE 800 sq.mm. 1/core 132 KV Cables

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The XLPE cables for 132kV should comply generally with the requirements of latest IEC 840-88 1) Conductor

The conductor shall consist of stranded, plain annealed electrolytic copper wires either circular and compacted or compacted segmentally Milliken type having a cross sectional area of 1000 sq.mm complying with IEC 228 and BS. 6360.

2) Conductor Water Sealing

The conductor shall be water sealed by adding a swelling material between the conductor strands.

3) Conductor Screen

This screen consists of an extruded layer firmly bonded to the XLPE insulation. The material is a semi-conductive compound. The interface between the screen and the insulation must be smooth as much as possible. The conductor screen, the insulation and the insulation screen are to be extruded in one single process “the triple extrusion process, the conductor screen shall have suitable thermal and mechanical properties. A non-hydro scopic semi conducting tape is to be applied between the conductor and the extruded semi conducting material.

4) Insulation

The insulation shall consist of one layer of extruded chemically cross-linked polyethylene (XLPE) which shall be dry cured. The insulation shall be firmly and continuously bonded to the extruded conductor screen a very clean grade of insulation is to be employed which is conveyed from sealed boxed to sealed extruded hopper without being exposed to atmospheric contamination.

The insulation thickness shall be designed to have a life time of more than 50 years based on working voltage of 132 KV r.m.s., and BIL ( Basic Impulse level of 650 KV. peak ). However, the nominal insulation thickness should not be less than 20 mm. The insulation thickness should be measured in accordance with IEC 811-11 clause 8, the average of the measured valves rounded to 0.1 mm shall not be less than the specified nominal thickness. The lowest measured value shall not fall below the specified nominal thickness by more than 10% of the specified nominal thickness:

tm > tn - 0.1 tn mm

5) Insulation Screen (core screen)

The insulation screen shall consist of an extruded layer of semi conducting

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compound. This core screen should be fully bonded to the insulation so that intimate contact with the insulation is ensured. Conductor screen, insulation, and core screen are to be extruded in one single process (the triple extrusion process). Two layers of conductive swelling tapes shall be applied over the extruded semi conductive compound.

6) Metallic Screen

The metallic screen shall consist of a combination of plain annealed copper wires applied concentrically and copper tapes applied helically semi conducting layer to be applied over the copper tape (as bedding) The metallic screen shall be capable to carry the return earth fault currents specified.

7) Metallic Sheath

To ensure the highest degree of protection against the ingress of moisture, the cable shall have a metallic sheath consists of lead alloy type "E" or type ½ C complying to BSS 801 or tellurium lead alloy sheath (Kb-pb Te 0.04) according to DIN 17640. The nominal thickness of lead sheath shall not be less than 3.3mm. - Short circuit current is 40 KA for 1.25 seconds

8) Armour

The cable shall be armoured over the lead alloy sheath, using stainless steel tapes or Tine Bronze or copper tape A suitable bedding of extruded PVC under the armour shall be used.

9) Anti Corrosion Covering

The cable shall have an outer covering of PVC jacket, the PVC shall conform to type 9 of table 1 of BSS 6746 the nominal thickness of the PVC outer covering shall be 4mm.

10) Graphite Coating

A thin layer of resin bonded graphite coating is to be applied to the anti corrosion

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9.3.3 XLPE 240 sq.mm. Single Core 132 kV Cables: i) Conductors: The conductors shall be of standard plain annealed high conductivity copper wires shaped

into circular cores of a cross sectional area 240 sq.mm. and formed with central oil duct of 12 mm.diameter.

ii) Conductor Screening: Two layers of semi-conducting carbon paper tapes of a total nominal thickness of 0.20

mm. iii) Insulation: The thickness shall not be less than the value corresponding to an impulse voltage level of

650 kV peak and system highest voltage of 145 kV but not less than 9.6 mm. iv) Core Screening: A metalized paper or non-ferrous paper metal type screen shall be applied over the paper

insulation of each core which shall be reinforced by a copper woven fabric tape. v) Sheathing: The cable shall then be drawn either into lead alloy ½ C confirming to BSS 801 or

tellerium alloyed lead ( Kb-Pb-Te—0.04 ) confirming to DIN 17640 and lightly reinforced by means of helically applied metal tapes. The minimum average thickness shall not be less than 2.3 mm and the minimum thickness at any point shall not be less than 2.16mm (see Clause 9.2.3 ).

vi) Serving & Bedding: The following layers shall be applied over the lead alloy sheath: a. Coating of water proof insulating compound. b. Suitable bedding and metal type reinforcement which shall consist of two layers of non-

magnetic material ( tin-bronze, stainless steel or hard copper ) and further served as follows:-

c. Outer covering of extruded Black jacket of minimum average thickness and minimum thickness at any point not less than the value given in 9.3.1 above. The PVC shall conform to BSS 6746 and shall fulfill the test requirements for PVC type 9 of table 3 of BSS 6746 as a minimum and shall be suitable for site conditions stated under clause 9.1.

The PVC sheath shall be embossed with voltage designation (132 kV ) and the manufacturer’s name and with the same manner described in BSS 6480 and ESI standard 09-4. The tenderers should submit with their offers a guarantee for the suitability of the PVC to site conditions mentioned in this specification.

d. Graphite coating. e. Overall lime wash. 9.3.4 Solid 1000sqmm Single Core 33kV PILC&S Cables: i. Conductors: The conductors shall be stranded plain annealed high conductivity copper wire shaped into

circular cores and shall have cross sectional area of 1000sq.mm. ii. Insulation: The insulation thickness should be designed for an impulse voltage of 195kV peak but the

thickness shall not be less than 6.8mm. iii. Screening: Screening over the conductor and over the insulation shall be provided as per clause

9.3.1(H). iv. Sheathing: Lead alloy E or ½ C Tellerium alloyed lead (KbPb-Te-0.04) minimum average thickness

not less than 2.3mm and minimum at any point not less than 2.08mm. v. Serving: Outer covering of extruded black PVC jacket of minimum thickness at any point not less

than the values given in Table 1 under clause 9.3.1 of this specification. The PVC shall conform to BSS 6746 and shall fulfill the test requirements for PVC type 9 of Table 3 BSS 6746 as a minimum and shall be suitable for site conditions stated under clause 9.1.

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The PVC sheath shall be embossed with voltage designation 33kV cross-sectional area of conductor and the manufacturer's name, manufacturing year and with the same manner described in BSS 6460 and ESI standard 09.3.

9.35 Solid 500 & 400 & 240sq.mm. Single Core 33kV PILC&S Cables: i) Conductors: The conductors shall be stranded plain annealed high conductivity copper

wires shaped into circular cores and shall have cross-sectional area of 500sq.mm / 400sq.mm. / 240 sq.mm as may be specified in the Details of Equipment.

ii) Insulation: Thickness shall not be less than 6.8mm and as 9.3.3(ii) above. iii) Screening: As 9.3.3(iii) above. iv) Sheathing: Same as 9.3.3(iv) above but with minimum average thickness and minimum at

any point as follows: - for 500sq.mm. & 400sq.mm. 1.9mm & 1.7mm - for 240sq.mm 1.8mm & 1.6mm v) Serving: As 9.3.3(v) above. 9.3.6 Solid, 1000sq.mm. 1/Core 33kV XLPE Insulated Cables: i) Conductors, shall be of stranded copper wires shaped in circular conductor and shall

have a cross-section area of 1000sq.mm. or 500sq.mm. complying to BSS 6360. ii) Insulation, XLPE as specified under clause 9.2.2(b) and in accordance with IEC

502. iii) Screening, shall be of semi-conducting thermoplastic or thermosetting material over

the conductor and similar layer extruded over the insulation as per IEC standard 502, but thickness should not be less than 8mm.

iv) Outer Sheath, shall be extruded PVC hard grade heat resisting type complying with BSS.6746(Table 1-type 9) and IEC 502 (clause 12).

9.3.7 Solid 500sq.mm. 1/core 33kV XLPE Insulated Cable: i) Conductors: same as 9.3.5 above but conductor cross-section area is 500sq.mm. ii) Insulation: same as 9.3.5(ii) above. iii) Screening: same as in 9.3.5(iii) above. iv) Outer Sheath, same as in 9.3.5(iv) above. 9.3.8 Solid 630sq.mm. 1/core 11kV XLPE Insulated Cables: The components of this cable is the same as that described above under 9.3.6. However,

the thickness of insulation, screen sheath, serving and bedding shall suit the rated voltage of 11kV and cross section of conductor and shall be in accordance with IEC standard 502.

9.3.8 Solid 500sq.mm & 630sq.mm. 1/core 11kV PILC&S Cables: i) Conductors: The conductors shall be of stranded copper wires shaped into circular cores and shall have

a cross sectional area of 500 and 630sq.mm. ii) Insulation: Thickness not less than 2.8mm. iii) Sheathing: Leading alloy E or ½ C or tellurium alloy nominal thickness not less than 1.8mm. iv) Serving: As 9.3.3(v) above. 9.3.9 Solid 3/Core 300sq.mm. & 185sq.mm 11kV XLPE Insulated Cables: i) Conductors: The conductors shall be of stranded copper wires shaped into circular cores and cross-

sectional area of core shall be 300sq.m.. and 185sq.mm. respectively. The conductor shall comply with BSS6360.

ii) Insulation: Cross-linked polythelene XLPE between conductors and between conductor and sheath as

specified under clause 9.2.2(b) above.

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iii) Screening: A semi-conducting screen shall be extruded over the conductor. This layer shall consist of

black semi-conducting thermo-plastic or thermosetting material, and shall be easily removable from the conductor. This layer shall have an average thickness of 0.38mm when measured over top of the strands and shall be cylindrical. A similar semi-conducting screen shall be extruded over the insulation without scratching the surface.

iv) Sheathing: PVC hard grade heat resisting type complying with BSS 6746 (Table 1- Type 9). v) Laying up and Bedding: The 3-core shall be laid up together with suitable semi-conducting tape, or an extruded

layer of semi-conducting material. vi) Armour: The cable shall be armoured with galvanized steel wires to give it mechanical strength and

also act as a low resistance earth return conductor. Electrical contacts shall be maintained between the core screens and the earthed armour through the conductive beeding.

vii) Short Circuit Rating: The cable shall carry without damages or undue stress a fault current of 18,000 Amps for

1.25 seconds after a continuous period of full load. Under these conditions, the final temperature of the conductor shall not be such as to damage the insulation.

9.3.10 Solid 1/Core 630, 500 & 300sq.mm 1000 Volts XLPE Cable: a) Construction: i) The conductors shall be of stranded copper wires shaped into circular conductors and shall

have a cross-sectional area of 300, 500 & 630sq.mm. shall comply with BSS.No. 6360. ii) Insulation: XLPE and it shall be applied by a combined extrusion and vulcanization

process and shall form a compact homogenous body. iii) Oversheath:PVC hard grade, heat resisting type complying with BSS.6746:1969 (Table 1-

Type 9). b) Current Rating: The current ratings of cables for the site and installation conditions mentioned above shall

be stated. These should be based on maximum conductor temperature in normal operating conditions not exceeding 90C. Where ratings are specified for only standard conditions, appropriate adjustment factors should be stated for Kuwait conditions.

c) Short Circuit Rating: Offers should be accompanied with short circuit current curves with XLPE insulation. It

is assumed the conductor is at its maximum operating temperature of 90C before the occurance of the short circuit and the maximum conductor temperature after a fault duration of 0.5 seconds will be 250C.

The cables shall carry the above short circuit currents without damage or undue stress. The formula used in evaluating the short circuit current should be stated. 9.3.11 34-Core Pilot and Telephone Cables: (associated with 132 kV Cable Feeder Tails) These cables are required for the conveyance of alarm, control, protection, telephone and

telemetry signals throughout the existing and future networks. These cables shall be of copper conductors, polythene insulated and polythene inner

sheathed armoured with galvanized steel wire armour and overall sheathed with PVC. The cable shall be insulated to withstand induced voltage level upto 15 kV and should generally comply with Electricity Supply Industry (ESI-09-6) standard as a minimum.

a) Make-up of Pilot Cables: i) 2-core (one pair): each core shall consist of copper conductor of cross-sectional area 2.5

sq.mm. \polythene insulated and the pair shall be screened for use with Solkor protection system.

ii) 4-core (two pairs ) : each core shall consist of copper conductor of cross-sectional area 2.5 sq.mm. polythene insulated and each pair twisted and screened for use with intertripping system.

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iii) Twenty eight cores : ( 14 pairs ) each core shall consist of copper conductor of cross sectional area of 0.645 sq.mm. unscreened and polythene insulated. Each pair shall be separated and twisted for use with telephony and telemetry system.

b) Conductor: The conductors shall comply with BS 6360 in so far as applicable for plain annealed

copper wires. c) Insulation: The cores shall be insulated with polythene of type (03) compound in accordance with

B.S.6234. The thickness of insulation shall not be less than 0.8 mm. d) Inner Sheath ( Bedding ) : The inner sheath shall consist of an extruded covering of black polythene which shall be of

type (03C) compound in accordance with B.S. 6234. The thickness of inner sheath shall not be less than 1.8 mm.

An overall screen made of copper around the 17 pairs shall be applied above the inner sheath. A suitable polythene bedding of minimum thickness of 0.5 mm. shall be applied over the overall screen.

e) Armour: The armour shall consist of one layer of galvanized steel wire complying with the

requirements of B.S. 1442 ( metric unit ) and of diameter not less than 1.6 mm. N.B. These cables shall be designed to withstand induced voltage level up to 15 kV.

However, the above insulation thickness and armour wire diameter are minimum and may have to be increased to suit the above induced voltage level and to meet the maximum attenuation requirements specified later.

f) Overall Sheath : The overall sheath shall consist of an extruded PVC jacket. It shall be also black in color

and withstand without deterioration during storage and site conditions outlined above. The PVC shall comply with B.S.No.6746/1969 (type 5 of table 1). The thickness of PVC overall sheath shall not be less than 1.9 mm. The sheath shall be embossed “ 34-core pilot cable ”, the name of the manufacturer and year of manufacturing.

g) Attenuation : The maximum attenuation of the audio pairs at 1KHz and at 10C shall not exceed 0.77

db/1000 M. The nominal attenuation of the audio pairs at the above conditions shall be 0.7 db/1000

meters. The measured attenuation shall be corrected by multiplying the value obtained (1 + .002 ) (T-10), where T is temperature of the cable in oC.

h) Cross-Talk: Cross talk between all pairs shall not be worse than 74 db at 1300 Hz. i) Impedance : Nominal impedance at 1KHz shall be 490 ohms. j) Method of Twining and Laying: The lengths of lay of conductors forming pairs shall differ for adjacent pairs and shall not

exceed 150 mm. The lengths of lay of the pairs shall be chosen so that cross-talk is as small as possible.

The direction of lay of successive layers is at the discretion of the manufacturer. k) Identification of Cores: The cores shall be clearly identified by colors. The following scheme of identification

shall be used :- Blue/White For solkor Yellow/White ) Intertripping and Green/White ) interlocking Brown/White ) Blue/White ) Blue/White/white ) Blue/Yellow/white )

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Blue/Green/White ) Blue/Brown/White) Blue/Slate/White ) Yellow/Slate/White ) Yellow/White/White ) Telemetry and Yellow/Green/White ) Telemetry Yellow/Brown/White ) Yellow/Slate/White ) Green/White/White ) Green/Brown/White ) Green/Slate/White ) Alternatively, the following scheme of identification can be offered: For solkor : Blue/White For inter-tripping : Red/Yellow Green/Brown For telemetry and : Black/Violet Telephony (Red/Yellow (Green/Brown, Alternative concluding Blue/White 9.3.12 Warning Tapes, Cable Protection Grid, Cover Tiles, and Joint Marker: The scope of this tender includes the supply of the necessary quantities of warning tapes

and cable protection grids and the installation of the same above the 630 sq.mm. 132 kV power cables, wherever the power cables are laid in the ground. The specification of these tapes and grids is as follows :-

a) Warning Tapes: The warning tapes shall be of orange colored (33 KV) & yellow colored (132KV). The

warning tapes shall be of high density polythene tape or any other alternative material. However, the materials offered should be suitable for site conditions mentioned under clause 9.1.

A guarantee for this suitability should be submitted with the offer. The tapes should not be less than 15 cms. width and 0.5 mm. thickness. This warning tape

should be labelled in capital letters, “ DANGER HIGH VOLTAGE CABLE” in both English and Arabic languages. The size of the letters should not be less than 4cms in length and the letters should be printed in black colour. A sample of this tape should be submitted with the offer and will be subject to MEW approval.

b) Cable Protection Net: A suitable cable protection net of yellow coloured (132kV) & orange (33kV) high density

polyethylene or any alternative materials suitable for site conditions mentioned in this specification.

A guarantee for this suitability should be submitted with the offer. The protection net shall be of 60 & 40cms and 2 x 60 and 2 x 40cms width for single

circuit and double circuits of 132 and 33kV cables respectively. The thickness of this protection net should not be less than 3mm.

The above tapes and protection grid shall be laid according to MEW specification for cable laying.

c) The 132kV cable feeder tails where laid in ground shall be protected by concrete tiles as per attached drawing No.MDA/1/560. At the free end of these cables, joint markers shall be supplied and installed as per drawing Nos. MC/7/143-E and MD/1//24E.

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9.4 Laying up of Power Cables: Soon after the works tests are completed, both ends of every length of cable shall be sealed

by means of a metal cup over each end and plumbed to the sheath. The ends shall be marked with the letters ‘A’ to ‘Z’ to indicate the running and tail ends respectively. Letter stamping shall be at least at two places for each end.

Tenderers are requested to include in their offer price for the provision of galvanized steel supporting bridges of the cage type with slides made inclined 30o to horizontal level. These bridges are needed for crossing of power cables to each other on the ground in the basement, avoiding touching so that current ratings are not affected. The design, dimensions and number of these bridges shall be sufficient to cover the crossing of all power cables included in this tender and also for future feeder cable circuits, however, this shall be subject to the approval of MEW site Engineer.

Provision of supporting structures and cable crossing bridges in the basement as may be approved by the Purchaser is also to be supplied for 11 kV outgoing feeders where cables will be supplied and laid by others.

9.5 Packing and Cable Lengths: Tenderers are warned that equipment is liable to every rough handling enroute from the

Factory to the site in Kuwait. It is essential that the packing is efficient and strong with extra reinforcement where necessary to ensure the safe delivery to site. All packages shall have the Purchaser’s order number, shipping marks and manufacturer’s identity mark clearly indicated.

The finished cables shall be wound on strong cable drums reinforced by rods of steel and provided with central core through which an axle can pass. The drums shall be provided with wooden battens to protect the cable from damage. The drums shall be adequately labelled to indicate particulars of cable, i.e. voltage, conductor size, number of cores, gross and net weight ...etc. The direction for rolling shall be recorded on the drum together with temperature at which measurement was made.

The drum length of each type of cable shall be proportioned to ensure that no straight through joints are needed. Drum and all packing shall be disposed off by carting to dump by the contractor and the cost of such shall be included in the offer price. All empty barrels are to be totally protected, closed for the re-use and to be collected, stored at a suitable place as per MEW instructions.

9.6 Cable Schedules & Records: The contractor shall take all records of the cables and submit 3 sets of standard 35mm

silver halide microfilm aperture cards photographed from the approved electrical & civil drawings for cables, and cable record drawings. The details of microfilm is given under clause 1.15 above.

The cable record drawings must be submitted, these records shall be carefully taken on site during the installation of the works. The final presentation of the records and schedules shall be approved by the Purchaser. The records shall show the routes, the exact location of each cable, the position of each termination and shall have schedules showing the phasing of joints, the date of jointing, the name of the jointer, the lengths between their terminations, the serial number of the cable drums, the direction of the lay of the cable, i.e. A and Z ends, soil conditions, positions of ducts and sectional inserts of cable trench giving the relative positions of the cable, tiles, depths and spacings. Any other services that cross the route of the cable shall be recorded. Measured values of resistance and capacitance shall be recorded for each length of cable between terminations. The records shall also include the route profile (to be measured by the contractor) with all the informations of the “As Built” hydraulic system ( No. of pressure tanks per phase, pressure tank and gauge levels etc... setting of pressure ... etc. ).

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9.7 Termination of 132 kV Feeder Tails: The arrangement of cables and the method of laying, installation and bonding shall be

subject to approval by the Purchaser. Cables, joints and terminations shall be supplied and installed in such a manner that the maximum voltage rise permitted on sheaths under full load conditions is 65volts. Bonding and earthing arrangements shall be suitably designed to meet this limitation. The minimum size of bonding lead shall be 300sq.mm copper and normally these shall be of the concentric type. All earthing connections shall be capable of disconnection for testing purposes by means of 3 single phase bolted links enclosed in water tight boxes.

9.8 Cable Laying and Installation: The cables will be partly buried directly in the ground and partly pulled through ducts.

Cables shall be laid direct from the drums into the trenches and special rollers shall be employed for this purpose. The cables shall be laid in Trefoil formation.

Where burying directly in the ground, the contractor shall excavate trenches of 1.5M depth from kerbstone, provide a bedding of 10cms of fine sieved sand at the bottom of the trench. After laying of power and pilot cables, the contractor shall provide a covering of soft sand to a depth of 15cms over the cable. Cable cover tiles shall then be laid over the line of the cable, covering both the power cable and its associated pilot cable. Each circuit shall be separately tiled.

Backfill the trench further 30cms of excavated material, laying of cable protection grid, further backfilling 20cms laying of warning tapes, completion of the backfilling to the normal ground level (See attached drawings).

Where cables are laid in concrete trenches or substation basement they shall be neatly arranged and single core cables shall be arranged in trefoil formation. Where cables are laid on trays or supported by cleats, they shall be neatly and symmetrically arranged. Cross-over shall be avoided as much as possible.

9.9 132kV Outdoor Sealing Ends: Where 132kV oil filled cables are to be terminated at one end by outdoor sealing end

boxes and other accessories, the creep age distance of the outdoor sealing end boxes shall not be less than 4818mm.

Tenderers shall attach to their offers drawings showing in detail the proposed method of terminating the cables. The other end of the cables shall be connected directly to outdoor 132kV switchgear through 1/core sealing end boxes.

The termination of the cables in the sealing ends shall also include the supply and installation of the necessary Hot dipped galvanized steel structures for supporting the sealing ends of the cables near the switchgear of the O/H line take off gantry, and shall also include making of the necessary foundations for the structures. These structures must be designed so as to make possible easy jump ring between the sealing ends and the switchgear bushings or the slack span conductor at the take off gantry.

The height of the steel supporting structures above ground level shall be such that the minimum clearance between the live parts and the ground shall not be less than 4600mm and the spacing between phases not less than 2600mm. Exposed cables shall be protected against sun rays by means of approved sun shield.

The installation work of these sealing ends shall also include the supply and installation of jump ring between the 132kV sealing ends and the slack span of the overhead line take off gantry including suitable bimetallic connections between the jump ring and the overhead line conductors. Also the sealing end shall have the suitable top connectors to connect the overhead line slack span to the sealing end.

The maximum distance between the sealing ends, take-off gantries or terminal towers can be taken jump ring arrangement shall be subject to MEW approval.

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9.10 Hydraulic Requirements: 1. An independent oil feed is required for each phase cable i.e. separate sets of tanks for each

phase. 2. "Long" routes shall be divided into separate hydraulic sections by using stop joints. 3. In each oil section under no load minimum temperature condition there should exist a

quantity of oil, known as “surplus oil”, which should be available to maintain pressure with an oil leak present until remedial section can be taken. As an absolute theoretical minimum quantity of surplus oil has been suggested as 10 litres but, in assessing practical designs. The Purchaser will expect to find proposals that load to quantities of surplus oil greater than this figure.

4. Preliminary hydraulic design details based on the foregoing principles and taking into consideration the cooling and heating transients will be settled with the Purchaser after the approved route has been issued. The contractor shall accept all requirements specified by the Purchaser’s Engineer at that time and at no extra cost if these requirements are greater than originally envisaged by the contractor at the tendering stage.

5. Pressure gauges shall normally be ranged from (1.00) to (+6.00) bars and be fitted at both ends of the oil section and also at both ends of the stop joints at least one pressure gauge with alarm contacts to be provided from one side of the oil section.

6. All hydraulic piping works, tanks...etc must be prevented from carrying power system fault current eg., by using insulating coupling connectors and all metallic parts of tanks, pipes...etc should be earthed.

7. Pressure gauges with alarm contacts shall be equipped with 2-stage contacts so as to detect a changed situation and bring out automatically in sequence the following actions:-

a) Firstly, an alarm signal to indicate that a pressure value has been dropped which is just below the minimum operating pressure.

b) Secondly, an initiation signal at emergency minimum pressure to cause the circuit be tripped out. The contractor shall wire up these contacts to marshalling kiosks provided by you in the substations. For en-route pressure gauges, the contractors shall connect these contacts via a suitable T-joint into an associated pilot cable. In case of using more than one set of stop joints in the feeder circuit, separate alarm cables to be used to transfer the alarm signals to the nearest substation from the concerned stop joint the price of which is included in tender price.

8. Gauges contacts shall be suitable for 240V AC/DC and each gauge terminals shall be connected to terminal blocks which shall be housed in water proof casing.

9. Valves: The oil control system shall be designed such that leak location and testing may be carried

out without the disconnection of any permanent pipework. Valves additional to those specified below shall be installed only with the approval of the

Engineer. i. Three valves per tank, one to feed the system, one to fill for boost the tank and one

for the gauge, the latter being of a three-way, two position type to facilitate testing of the gauge.

ii. One per manifold where two or more tanks are installed in an inaccessible position and the tanks are feeding to a single position.

iii. One for each individual oil feed. 10. Provision shall be made for the hydraulic testing of gauges i.e. it should be possible test

LOP alarms alarms by reducing the pressure in the gauge. If it is not possible to employ test blocks then the contractor should ensure any gauge, bleeding pipes shall be sealed off with a blank nut and nipple so that unintentional operation of valves will not result in loss of oil.

11. Oil pipes should be either PVC insulated copper or PVC oversheathed, steel armoured lead depending on circumstances of use-copper for inside substation and in open pits, but armoured lead for all buried applications. Buried pipes should be protected by cover tiles,

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protection net and warning tape. 12. Oil tanks and other hydraulic equipment should be provided with purpose-made earthing

lugs or bosses. Bonding cables for hydraulic equipment shall be of suitable size, copper, PVC insulated, single core.

9.11 Bonding and Earthing Requirements for 132/33kV Cables: For 132 & 33kV Cable Tail Circuits to O/H lines:

A- For 132kV Cable Tail Circuits: 1. Single point bonding of the power cable lead sheaths is required to eliminate sheath

circulating currents. 2. Cables and terminations shall be designed, manufactured and installed so as to result

in a fully insulated sheath and to permit the routine application of PVC over sheath test 10kV DC for 1 minute prior to commissioning and during the first two years of service, the anti-corrosion covering to be tested at six monthly intervals at 5kV DC for one minute.

3. The maximum permitted sheath standing voltage to earth under full load conditions shall be 65 volts.

4. For 132kV cables a stranded 300sq.mm. copper earth continuity conductor insulated with PVC (minimum average thickness 3.3mm) complying with BS 6346 so far as it applies, shall be provided along the whole length of each single point bonded circuit and in close proximity to the power cables with cables laid in flat formation, the earthing cable shall be installed between two of power cables and transposed midway. The earthing cable shall be connected at both ends to the main substation earthing system and at suitable position to the main sheath bonds for 33kV cables the cross section of earth continuity conductor shall be 120sq.mm.

5. Sheath voltage limiter units (SVL's) shall be connected to the unearthed end(s) of the tails. The star point of the SVL's shall be connected to the earthing cable specified in (4) above.

6. All sheath bonding connections shall be made via disconnecting link boxes so as to facilitate routine over sheath integrity testing. All bonding leads shall be PVC insulated, of conductor size 300 sq.mm. copper and be made as short as possible.

7. Link boxes shall be galvanized steel with lockable lis bearing externally the legend "DANGER – ELECTRICITY" and internally the legend "THESE LINKS MUST BE CLOSED WHEN THE CABLE IS IN SERVICE". The insulation shall be such as to withstand an impulse test of 17.5Kvp from link to earth and 37.5KV between links. Link contact resistance shall not exceed 20 micro-ohms. Links and contacts faces shall be tinned copper and shall be held firmly together by bolts. The legends should be written in both Arabic and English words.

8. Inside substations, the bonding cable from the "Earthy" end of the link box shall be connected to the inner earth ring bar. The specified 300 sq.mm. bonding cable shall be used to connect to the substation earthing system. The connection to the substation earth bar shall be made by brazing a flag connector to the bar and bolting the bonding. Inside substations, the bonding cable from the "Earthy" end of the link box shall be connected to the inner earth ring bar. The specified 300 sq.mm. bonding cable shall be used to connect to the substation earthing system. The connection to the substation earth bar shall be made by brazing a flag connector to the bar and bolting the bonding cable lug onto the flag cable lug onto the flag.

9. On termination glands there need to be earthing connection flags or bosses of sufficient size to accommodate the connection to the specified size of bonding cable.

10. On flanged joint sleeves there should be two such flanges, one on each side of the flanges that the bonding cable can be connected to both sides of the sleeve without having to rely on the electrical continuity of the flange bolts.

11. The foregoing paragraphs represent summary of significant requirements but it is expected that in case any queries arise on this topic reference would be made to internationally recognized source documents which would include the following:

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1. Electra paper No.28, May 1973 by Study Committee No.21. The design of

specially bonded cable system (also follow up paper No.47). 2. British Electricity Board document C55/2 insulated sheath power cable

systems. For 33kV Cable Tails to Overhead Lines: The sheath will be solidly bonded from both sides (as switchgear and at outdoor sealing

ends). B- Earthing Requirements for 132 & 33kV Complete Feeder Circuits: 1. Solid bonding of the power cable lead sheaths is required. The overall design shall

be such as to permit the routine application of PVC over sheath tests (10KV) DC for 1 minute prior to commissioning and during the first two years of service, (5KV) DC of 1 minute.

2. At straight joints the lead sheaths of the three single core cables forming one circuit shall be bonded together using insulated bonding cable (see 4, below) but without making any special provision for disconnection during sheath testing. The overall installation shall be sufficiently insulated from earth so as to withstand the sheath test. The connection to the lead sheath s may conveniently be made by connecting the bonding cable to the joint sleeves. If the sleeves are flanged then the bonding cable must be connected to both sides of the continuity of the flange bolts.

3. At terminations and trifurcating joints the lead sheaths of the three single core cables forming one circuit shall be connected to earth using insulated bonding cables (see 3, below) and via 3-phase link boxes (see 5, below).

4. Bonding cables for power cable sheaths shall in all cases, be of single core, 300 sq.mm. stranded copper, PVC insulated construction. The size of cable shall be used regardless as to the anticipated magnitude of fault current at any particular point in the network. The insulation thickness shall be 3.3 mm minimum average. The cable shall be embossed with the wording "ELECTRIC CABLE" – BONDING LEAD" and the outer surface of the PVC shall be graphite coated. The construction of the cable shall be in accordance with B.S. 6346 in so far as it applies. The insulation shall be spark tested at 25kV DC for 1 minute.

5. Link boxes shall be galvanized steel with lockable lids bearing externally the legend "DANGER – ELECTRICITY" and internally the legend "THESE LINKS MUST BE CLOSED WHEN THE CABLE IS IN SERVICE". The insulation shall be such as to withstand an impulse test of 17.5Kvp from link to earth and 37.5Kvp between links. Link contact resistance shall not exceed 20 micro-ohms. Links and contact faces shall be tinned copper and shall be held firmly together by bolts.

9.12 Joint Pits and Oil Pressure Tank Pits: All oil filled cable joints and oil pressure tanks shall be housed in suitable pits which shall

be designed and built in accordance with the following requirements for those either within or outside the boundary walls of substations. These pits (except buried type) shall be of prefabricated structural elements.

All pits, except buried type shall be provided with galvanized steel ladders and shall be such as to prevent the ingress of rain or ground water. The size of all pits shall be such as to allow comfortable working space for jointers. These pits shall be provided with manhole cover of adequate size to allow the removal of any equipment that may be required, this cover to be of circular type with clear opening of minimum diameter of 75 cms ready made cast iron. Padlocks shall be provided to manhole covers.

Tenderers shall submit design drawings and calculations which will be subject to the approval of the Purchaser. Nor more than one set of joints or one set of tanks shall be located in each pit (set per circuit). Also it will not be permitted to pass more than the cables of one circuit inside the pit, and thus if two circuits were specified, the cables of the

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2nd circuit will pass under the pit in concrete encased asbestos ducts to be constructed under the pit. The cost of this duct is included in the pit prices.

A) Pits within Substation Boundaries: Pits for joints and tanks shall be consisting of cast insitu concrete floor slab minimum 15

cms thick and reinforced with suitable steel mesh, 15 cms thick precast reinforced concrete walls with fair face finish internally. Top slabs shall be made of precast reinforced concrete, removable strips with a maximum width of 70 cms and each to be provided with galvanized steel handles for lifting and shall be adequate to sustain a wheel load of 4 tonnes or superimposed load of 500kgs/sq.M and to be designed in a manner to stop rain water. The level of the top cover shall be 20 cms above yard level. Suitable concrete or steel bollards shall be provided around the pits, 75 cms hgh and spaced at one metre centers.

1. In-situ concrete mix to be 1:2:4 with crushing strength of 240 kg/sq.cm. Crushing strength for precast reinforced concrete to be 320 kgs/sq.cm. 2. Stability shall be required for the pit as one unit under several working conditions. NB: For all 33kV cables, the contractor has to construct the above pits having suitable

dimensions. For 132kV cable circuits wherever it is specified that cables will be jointed to the SF6 switchgear, the contractor will have to construct the above pits and this should have internal dimensions of 3.5x2x2 M. However, for all the 132kV circuits where it is specified that cables will be jointed to 132kV cable tails laid by others. The contractor will construct a pit inside the substation for each 132kV cable circuit and having the same dimensions 3.5x2x2M and he will use this pit for accommodation of his oil tanks necessary for the circuit.

B) Pits outside Substation Boundaries: 1. Pits for straight joints shall be semi-buried type and shall consist of pre-fabricated

elements or steel mesh reinforced concrete base slabs minimum 15 cms. thick, concrete block walls and 30 cms. deep top R.C. the beams. The joint shall be protected using fiber glass sleeve and the space between the outer joint sleeve and the fiber glass sleeve shall be filled with bitumen. The completed joints shall be surrounded by sieved sand carefully compacted by hand to depth of 10 cms. above the top of the fiber glass sleeves. Precast paving slabs shall be placed on top of the pit back-filled with selected sand up to ground level. Suitably marker pad shall be placed on top of the pit back filled with selected sand up to ground level. Suitable marker pad shall be positioned 5cms above the surface. The whole arrangement shall be subject to MEW’s approval. Where sheaths bounding link boxes are required, they shall be installed in shallow pit adjacent to the straight joint and accessible from the surfaces where required asbestos or PVC 6" inch pipes to be encased in the concrete blinding to avoid blocking of electrical reserve for other circuits and their cost shall be included in the pit prices.

2. Pits for feeder joints and oil pressure tanks shall be of similar designs to (A) above, except that the covers to be designed to sustain a wheel load of 10 tonnes to the effect of a vehicle mounting adjacent to the pit top slab which shall be at a level of 20 cms above the ground level.

C) Link Boxes for Bonding : Link boxes for bonding purposes shall be installed in the basement near the respective

cable circuit and preferably to be wall mounted in such a manner as to be accessible at all times. In the case of unfilled joint pits, the link boxes may be positioned inside the pit itself. Bonding lead connections between joints and link boxes shall be suitably protected from mechanical damage. Contractors shall include in their submission showing the detailed arrangements proposed for installing these link boxes in each of the various circumstances specified.

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D) Earthing and Bonding of Oil Tanks: Insulated inserts are required in oil feed pipes to joints. Oil tanks shall be bonded and

connected to outdoor earthing ring by means of (30 x 5)sq.mm copper tape. Other hydraulic equipment such as oil pressure gauges shall be connected to indoor earthing ring by means of 2.5sq.mm copper conductor. The incoming armour wires of pilot cables should not be bonded to the alarm gauge metal work.

9.13 Asbestos Pipes: 1. All cables shall pass through approved ducts under roads and elsewhere as directed

by the Engineer. 2. Ducts shall be of 4" and 6" diameter asbestos pipes, purchased from the National

Industries Co. 3. Pipes shall be of standard quality with minimum crushing strengths of

450Kgm/sq.cm laid as one single length piece under the road or each carriageway where possible, both ends of pipe cut perfectly perpendicular to the body.

4. If more than one single length is to be used, both ends of pipes shall be butt-jointed, held firmly together in position wrapped with building paper or other approved material before casting of surrounding concrete.

5. All asbestos ducts shall be laid in mass concrete mix 1:3:6 extending 10cms below the bottom and 15cms above the top duct with 5 cms separation between the ducts.

6. Cement to be used for encasing of concrete shall be ordinary portland sand and coarse aggregate to comply with the specification.

7. Small lengths or cut pieces of pipes with multiple jointing to make one single length under any road crossing shall not be permitted.

8. Pieces of pipes shorter than 3.00metres long shall not be used unless under unavoidable circumstances.

9. All depths at which the ducts are to be laid under road crossing shall be agreed with the Engineer.

10. Both ends of all spare ducts under road-crossings shall be plugged by the appropriate soft wood plugs of tapering type approved by the Engineer before backfilling.

11. After laying of power and control cables through ducts, a sealing material such as Dense Mastic (plast) shall be used. It is necessary at first to clear the ducts of loose material by air jetting. The cables should be maintained centrally in the duct so that the sealant forms an even anulus around the cable.

9.14 Control Cable & Power Service Cables: All control and power service cables A.C and D.C including the multicore cables shall be

PVC tropical grade insulated cables and shall generally conform to the requirements of BS6346 and 6746 wherever applicable.

The multicore cables for control, alarm, indication, protection, current and voltage transformers secondary circuits shall be of 600 volts grade and those required for power service in the substation shall be 1000 volts grade.

Control and power cables supplied should be suitable for initial storage in the open yard and for continuous service after laying without any deleterious effects on the insulation and /or sheathing.

The control and power cables shall be tested in accordance with BSS 6346 and 6746 unless otherwise approved.

Tenderers shall furnish general particulars and guarantees for the cables specified as called for in the schedules.

Except when otherwise specified, the smallest cross section area of control cable conductors to be used shall be 2.5sq.mm.

Regarding internal wiring of relay panels, wired of cross sections 1.5sq.mm and 0.8sq.mm

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can be used for signal circuits and connections between modules of electronic relays (if applicable) and as required under class 1.10 of the specifications.

All control cables between sub-station equipments shall be of the fire-retardant type in accordance with IEC. Publication 332-1970 and BSS 4066 Part 1/1980 as required in clause 8.4.5 (iii) of this specification.

The contract price shall include cleats, trays and other fixing arrangements for the cleats and trays, etc....in the basement or trenches and they shall be subject to the approval of the Purchaser.

The contractor shall not be entitled to any extra charge required to complete the work according to drawings as finally approved by the purchaser, cable terminal glands and other accessories including material that may be required to prevent entry of vermin and dust into the cubicles shall be applied.

Particular attention should be given to cable entries from basement into the switchgear, control and relay boards, L.T. distribution board and battery charger cubicles, etc....where necessary, bottom plates with all the necessary terminal glands and fire resisting material has to be provided to prevent access to vermin from underneath the equipment and to prevent spread of fire from one zone to another.

When designing control cable layouts, the contractor shall provide sufficient trays to accommodate one or two layers of control cables only on any one tray. All iron trays, iron cleats and cleat parts and iron supports shall be hot dip galvanized. Control cables exposed to sun should be protected in an approved manner.

9.15 Factory Testing: The contractor shall carry out all routine and type tests on all equipment and accessories

included in the contract in accordance with the relevant British Standard Specifications unless otherwise approved. The contractor shall carry out any additional tests that are necessary to determine that the work complies with the requirements of this specification.

All samples used for testing shall be at the contractor’s expense and shall not affect the lengths of cables to be supplied under this contract. This also applies to other accessories.

All instruments used for testing purposes shall, if approved by the Engineer, be calibrated by an approved authority.

9.15.1 Control Cable Tests: The cables shall be tested in accordance with BS.3346 and 2746 as applicable or V.D.E

unless otherwise approved. A) Routine Tests: All lengths of completed cables shall be tested before despatch according to the following: 1) Voltage tests: The completed cable shall be subject to a voltage of 3KV r.m.s for five minutes. 2) Insulation Resistance Tests: The insulation resistance between each conductor and the remaining conductors in

the cable which shall be bunched and earthed shall be measured immediately after the voltage test in (1) above and shall not be less than 15meg.ohms.

3) Conductor Resistance: The conductor resistance shall be measured and the same shall not be greater than

the guaranteed figures. B) Type Tests: Measurements of thickness of insulation and sheath. A representative sample of each type and size of manufactured cable shall be examined

and the minimum and average thickness of insulation and sheath determined. These shall not be less than

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the guaranteed long and shall be taken not less than 30cms from the end of drum length. The PVC insulating and sheath of the cable shall be subjected to the tests specified in

Table 1 and 2 of BSS 6746 and shall comply with the requirements stated therein. All samples used in the above tests shall be to the cost of the contractor and shall not affect the length of the cables to be supplied under this contract.

9.15.2 Power Cables (132kV, 33kV & 11kV Cables): A) Routine Tests: All lengths of cable shall be tested before despatch according to the following:- i) Conductor Resistance Tests: The copper resistance of the conductors shall be measured by direct current at room

temperature and corrected for temperature in accordance with I.E.C. Publication 141-1 and BSS 6480. The values thus obtained shall not be greater than the guaranteed values stated in the Schedules or more than 4% greater than the calculated values as per I.E.C. Publication 141-1 and BSS 6480.

ii) Capacitance Tests: The electrostatic capacitance of each drum length of completed cable shall be

measured at power frequency and shall not be greater than the guaranteed values stated in the schedules.

iii) High Voltage Tests: The voltage tests shall be carried out with alternating current in accordance with

BSS 6480 for solid cables and I.E.C. 141-1 for oil filled cables. iv) Dielectric Power Factor/Voltage Tests: Each drum length of completed 132kV and 33kV oil filled cables shall be tested for

power factor at normal frequency and at ambient temperature and at 50, 125 and 200% of normal voltage. The power factor of the charging KVA after correction to a temperature of 20oC shall not exceed the guaranteed values stated in the Schedules or the values stipulated in I.E.C Publication 141-1 whichever is smaller. For 33 and 11kV solid cables, the power factor shall be in accordance with BSS 6480.

v) Voltage Test on Anti-Corrosion Covering: This shall be carried out in accordance with BSS 6480 where extruded PVC

oversheath is specified. Accessories: Tests analysis of plumbing and solder to check in compliance with BSS 219. Tests should

be carried out on samples selected from each batch. B. Type Tests: 1. Power Cables: The following tests shall be made on samples taken from cables manufactured for the

contract. i) Measurements of Thickness of Insulation: Sheathing, Serving and Weights: A sample shall be selected from each 40 meters of each type of completed cables, and

shall be at least 60 cms long. Then the minimum and average thickness of insulation shall be determined and the paper checked for wrinkles or tears. The minimum and average thickness of lead sheath, armouring and the various coverings of the bedding and servicing shall be determined, and these shall agreed with the guaranteed values. Also the weights of copper, lead and steel per meter of cable shall be determined.

ii) Bending Tests: The bending test shall be made on a sample of the completed cable (with all coverings)

having a length of not less than hundred times the diameter of the lead sheath. The bending tests shall be conducted in accordance with IEC publication 141-1 for oil filled cables and BSS 6480 for solid cables.

The samples shall then be power frequency high voltage tested in accordance with BSS 6480 for solid cables and IEC Publication 141-1 for oil filled cables.

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A specimen taken from the sample that has been tested shall then be dismantled and examined. The condition of the paper insulation, lead sheath, protective covering and armour shall comply with the requirements of BSS 6480.

iii) Loading Cycle-Power Factor Tests: For 132kV and 33kV Cables: This test shall be carried out on a sample of cable selected from the contract works. The

sample shall be complete with sealing end boxes and other accessories and shall be not less than 30metres in length with adjacent accessories not less than 4 meters apart and shall be laid out on the floor of the test bay.

The sample shall be heated up to the maximum conductor temperature stated in the guarantee schedule by passing current through conductors. During the twenty days of the test, the cable shall be alive at 1.5 x the service voltage. The heating current shall be mentioned at 50oC above normal maximum temperature or at least three hours and switched off for 18 hours and the cycle repeated twenty times. The power factor of the charging KVA shall be measured at 50% and 150% of the normal voltage as follows:-

a) Before the commencement of the test. b) When the cable has reached maximum temperature during each cycle. c) When the cable has cooled to minimum temperature during each cycle. The power factor shall, in addition, be measured at normal voltage at temperature of above

60oC and 40oC during cooling in each cycle. The power factor at the stipulated voltage shall not vary substantially from cycle to cycle.

iv) Dielectric Thermal Resistance Test: (For Oil-Filled Cables) A sample of the cable selected by the Inspector shall be tested for thermal resistance of the

dielectric at the maximum temperature to operate and under stipulated conditions. v) Mechanical Test on Pressure Retaining Sheath: (For Oil-Filled Cables) A sample of the cable at least 3 meters long is to be maintained for seven(7) days at

internal pressure equal to twice the maximum pressure during which period no leakage shall occur. This applies to oil-filled cables only.

vi) Dielectric Security Test: (33kV & 132kV Cables) A sample of the cables at least 10metres in length (excluding terminations) shall be

subjected at ambient temperature to a power frequency test voltage applied between conductor and screen. The value of the test voltage shall be 47.5kV cables and 190kV for 132kV cables and it shall be applied for 24 hours without the occurance of a breakdown of the insulation or flashover of the sealing ends.

2. Accessories: (Oil-Filled Cables) Pressure test on pressure gauges and alarm gauges shall be carried out in accordance with

Clauses 21 to 26 of I.E.C Publication 141-1. 9.15.3 1000Volts Single Core Cables: The cable will be tested in accordance with BSS6346 or 6480. The measurement of thickness and weight sample tests shall be carried out on one metre

length of cable. The minimum and average thickness of insulation shall be determined and these shall

agree with the guaranteed values. Also the weight of copper per meter of cable shall be determined.

9.15.4 Pilot Cables and Accessories: A) Routine Tests: i) Conductor Resistance Test: The resistance of the conductors shall be measured as specified in B.S.6360/1969 and

shall meet the requirements of this standard.

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ii) Voltage Routine tests: The voltage test shall be made with alternating current of approximately sine form at any

frequency from 40-62 Hz. inclusive. The voltage shall be increased gradually and maintained continuously for one minute at 10 KV (rms) between all unscreened conductors whilst excluding the single screened pair by connecting its cover and screen to the centre tap of one 10 KV. For screened pair, a separate 10 KV DC test shall be conducted with the screen connected to zero potential connection and 15 KV (rms ) between conductors and armour which shall be earthed.

Alternatively, the following D.C. test procedure may be followed :- Core-Core : 20 KV D.C with the screen maintained at the intermediate level of 10

KV D.C. Core-Core : 30 KV. D.C. with the screen connected to the cores. iii) Mutual Capacitance Test: The mutual capacitance of the cable shall be measured between the two conductors of

each pair with the other conductors and the armour earthed. The measurements shall be made using alternating current and a suitable bridge and the mean value obtained shall be recorded.

iv) Capacitance Unbalance Tests: Pair to pair capacitance unbalance measurements shall be made at audio frequency. All

conductors other than those under test being connected to the armour and earth. The measured values shall be divided by :½

( L/500 + V L/500 ) Where L is the length in meters. Lengths less than 100 meters shall be considered as 100

meters. No corrected unbalance measurements shall exceed 500 pf. The corrected unbalance

between carrier pairs shall not exceed 50pf. In order to limit the amount of testing, measurements will normally be made between adjacent pairs, except that all combinations between carrier pairs shall be measured. The measured values of capacitance unbalance shall be recorded for use in the preparation of jointing schedules to obtain the necessary balance to meet the cross-talk requirements.

v) Mutual Inductance: Mutual inductance measurements shall be made at 5KHz on carrier pairs. The measured

values shall be divided by:½ ( L/500 + V L/500 ) Where L is the length in meters of the cable under test, lengths less than 100 meters being

considered as 100 meters. The corrected mutual inductance shall not exceed 0.50mH. vi) Galvanized Routine Tests: Samples selected by the Purchaser’s representative of all galvanized material shall be

subjected to the galvanized tests set out in BSS.443 (testing of zinc coating on galvanized wires).

vii) Insulation Resistance Tests: The insulation resistance shall be measured between each conductor and the other

conductors connected to armour by applying 500 V. D.C. for one minute. The insulation resistance shall not be less than 12500 mega ohm/km at 20oC.

viii) Extruded PVC Over-sheath Test: Extruded P.V.C. over-sheath shall be spark test in the manner described in Clause 16.2 of

B.S. 6346. ix) Voltage Test: Voltage test on anti-corrosion covering in accordance with BSS 6480. B) Type Tests: i. Measurement of Thickness of Insulation, Sheathing, Armouring, Serving and

Bedding: Ten representative samples of the manufactured cables shall be examined and

average thickness of insulation, sheathing, armouring, bedding and serving shall be determined. The samples shall be at least 60cms long and shall be cut not less than

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30cms from the end of the drum length. Also, the weights of copper and steel per metre of cable shall be determined.

ii. Voltage Test: A sample of the manufactured cable together with a joint box shall be tested and

shall not break-down when a voltage of 5kV is applied for 5 minutes between pilot cores and between core and the lead connected to armour. Subsequently, the sample shall be tested and shall not breakdown when a voltage of 2.5kV is applied for five minutes between screened cores and between each screened core and the armour. Screens and armour shall be earthed during this test.

C) Accessories: i) Visual dimensional checks on selected samples at each batch of joint boxes (not less than

one joint box of each 50 boxes). ii) Tests check inner lead sleeve composition. iii) Test analysis of plumbing and solder to check in compliance with B.S. 219. Tests should

be carried out on samples selected from each batch (but less than one sample of each 200 sticks).

9.15.5 Site Tests: 1) Power Cables: After complete installation of the various circuits and before commissioning, each circuit

shall be subject to the following tests: i) Resistance Measurements: The copper resistance of each core of the completed circuits shall be measured and the

ambient value corrected to 20oC. ii) Capacitance Measurements: The capacitance between phase and between each phase and the lead sheath shall be

measured and the ambient temperature recorded. iii) High Voltage Tests: After the circuit has been brought upto its design oil pressure, a D.C. voltage of 270kV

shall be applied to 132kV cables between each core and screen for a duration of 15minutes, the other two phases being earthed. The high voltage test as well as the oil tests will be carried out on each circuit when it is completed by the cable contractor under a separate cable contract. However, the substation contractor has to co-ordinate and co-operate with the cable contractor and should carry out all the necessary works at the substation end for such tests.

Where 132kV cable feeder tails are required in connection with cutting-in of 132kV overhead line cables, the substation contractor shall carry out the H.V. and oil tests on each completed circuit.

iv) Special Bonding Equipment Tests: a) With all earthing links removed, the PVC over-sheath shall successfully with stand a

test voltage of 10kV D.C applied between lead sheath and earth for one minute. During this test, the lead sheaths of the other two phases shall be earthed. The test shall be repeated on the other phases in turn.

b) With bonding links disconnected, a suitable variable voltage D.C. test supply be applied in turn between each of the 3 disc leads and the earth lead. The resulting currents shall be measured and after correction for ambient temperature, shall lie within the declared limits. With the 3 disc leads then connected to the earth lead and all four disconnected from earth, the resistance between them and any metallic casing shall be not less than 10M when measured on a 1000volts ‘Megger’.

c) Contact resistance measurements shall be made across link faces and SVL connections. The resistance of the former shall not exceed 20 and of the latter 50.

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2) Pilot Cables: a) After Laying and Before Jointing: The following tests shall be carried out on each length of cable: i) Continuity: The continuity of all conductors shall be confirmed. ii) Insulation Resistance: The insulation resistance of individual lengths shall be measured between each

conductor and other conductors connected to the armour by applying 500V D.C. for one minute.

b) After Laying and Jointing: The following tests shall be carried out in each laid and jointed cable:

i) Voltage Withstand Tests: Each laid and jointed cable shall be subjected to the following high voltage tests: 1) Each of the unscreened pairs shall be tested with 15kV D.C. applied between the

two conductors of the pair. 2) For screened pairs, the following tests shall be carried out: a) 10kV D.C between the conductors of the screened cores with the screen

floating. b) 5kV D.C between the conductors of the screened cores and the screen which

shall be earthed. 3) 25kV D.C. between all conductors and screen jointed together with the armour the

screen during the test shall not be earthed while the armour shall be earthed. ii) Conductor Resistance: The conductor resistance shall be measured and recorded. iii) Insulation Resistance: The insulation resistance shall be measured between each conductor and the

other conductors connected to the armour by applying 500volts D.C for one minute.

iv) Attenuation, cross-talk and impedance test in accordance with ESI 09-6 standard.

9.16 Test of Power Cables (132 & 33kV) & 11kV & 1kV: 9.16.1 XLPE Cables: The tests shall be carried out generally in accordance with IEC 840 for 132kV cables and

IEC 502 for 33kV ^ 11kV cables unless otherwise specified hereunder. A- Routine Tests: The following tests shall be carried out on each manufactured length of cables, to check

that the whole of each length complies with the requirements. 1. Conductor Resistance Measurement: The complete cable length shall be in the test room, which shall be maintained at a

reasonable constant temperature for at least 12 hours before the test. If it is doubtful whether the conductor temperature is the same as the room temperature the resistance shall be measured after the cable has been in the test room for 24 hours. Alternatively, the resistance shall be measured on a sample of conductor, conditioned for at least 1 hour in a temperature controlled bath.

The DC resistance of the conductor shall be corrected to a temperature of 20ºC and 1KM length in accordance with IEC Publication 228.

The DC resistance of the conductor at 20ºC shall not exceed the appropriate maximum value specified in IEC Publication 228 if applicable.

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2. Measurement of Capacitance: The capacitance shall be measured between conductor and metallic screen. The

measured value shall not exceed the nominal value specified by the manufacturer by more than 896.

3. Partial Discharge Test: The partial discharge test shall be carried out in accordance with IEC Publication

885-2 except that the sensitivity as defined in IEC publication 885-2 shall be 10pC or less.

The test voltage shall be raised to and held at 1.75 Uo for 108 and then slowly reduced to 1.5 Uo.

The magnitude of the discharge at 1.5 Uo shall not exceed 10 pC. 4. Voltage Test: The voltage test shall be made at ambient temperature using an alternating test

voltage at power frequency. The test voltage shall be raised gradually to the specified value which shall then be

held for 30 minutes between the conductor and metallic screen. The test voltage shall be 2.5 Uo. No breakdown of the insulation shall occur. 5. Electrical Test on non-Metallic Sheath: The non-metallic sheath shall be subjected to the routine electrical test specified in

IEC publication 229. B- Sample Tests: General: The following tests shall be made on samples of manufactured cables, the number of

samples chosen shall be limited to not more than 10% of the number of lengths: 1. Conductor examination. 2. Measurement of thickness of insulation and non-metallic sheaths. 3. Measurement of the thickness of metallic sheaths. 4. Hot set test for XLPE insulation. The above tests shall be carried out in accordance with the requirements of IEC 840 for

132kV cables and IEC 502 for 3kV cables and shall fulfill the values given therein. C- Type Tests: General: The appropriate type tests specified hereunder shall be made before the manufacturer

supplies on a general commercial basis, a type of cable covered by this standard, in order to demonstrate satisfactory performance requirements. The type tests shall comprise the electrical tests on the complete cable and the appropriate tests on cable components.

D- Electrical Tests on Complete Cable: The following sequence of tests shall be performed on samples of complete cable at least

10 meters in length excluding the test accessories. 1. Bending test followed by partial discharge test 2. Tan Delta measurement 3. Heating cycle voltage test, followed by partial discharge measurement 4. Impulse withstand test followed by a power frequency voltage test. The above tests

except (2 above) shall be applied successively on the same samples. Details of Tests I. Bending test followed by partial discharge test: a. The sample shall be bent around a test cylinder (e.g. the hub of a drum) at room

temperature for at least one complete turn. It shall then be unwound and the process repeated except that the bending of the sample shall be in the reverse direction.

This cycle of operation shall be carried out three times in total. b. The diameter of the test cylinder shall not be greater than:

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25 (d +D) + 5% for cables with lead and corrugated aluminium sheath or with overlapped longitudinally applied metal foil: 20 (d + D) + 5% for others Where: D = measured external diameter of the cable in millimeters. D = measured diameter of the conductor in millimeters. c. On completion of this test, the cable shall be subjected to the partial discharge test

magnitude of the discharge at 1.5 Uo shall not exceed 5 pC. 2. Tan Delta Measurement: a. The sample shall be heated by a suitable method and the temperature of the

conductor determined either by measuring its resistance or by thermocouples on the surface of the screen, or by thermocouples on the conductor of another sample of the same cable heated by the same means.

The sample shall be heated until the conductor reaches a temperature equal to the maximum rated temperature of the insulation in normal operation within +/-5ºC.

b. Tan delta shall be measured at a power frequency voltage of Uo at the temperature specified above.

c. The measured value shall not exceed the value specified in table II of IEC 840. 3. Heating Cycle Voltage Test: a. The sample shall be in a U bend having diameter specimen. b. The sample shall be heated by a suitable method, until the conductor reaches a

temperature which shall be not less than 10ºC and not greater than 15ºC above the maximum rated temperature of the insulation in normal operation.

c. The heating shall be applied for at least 8 hours and shall be followed by at least 16 hours of natural cooling. The conductor temperature shall be maintained within the stated temperature limits for the last 2 hours of each current loading period.

d. The cycle of heating and cooling shall be carried out 20 times. e. During the whole of the test period a voltage of 2 Uo shall be applied to the sample. f. After the final cycle the sample at ambient temperature shall be subjected to and

comply with the requirements of the partial discharge test in accordance with sub-clause 1-C above.

4. Impulse Voltage Test (followed by A.C. voltage test): a. The impulse test shall be performed on the sample at a conductor temperature which

shall be not less than 5ºC and not greater than 10ºC above the maximum rated temperature of the insulation for normal operation. The impulse voltage shall be applied according to the procedures given in IEC publication 230.

b. The cable shall withstand without failure 10 positive and 10 negative voltage impulse of the appropriate value specified in Table I of IEC 840.

c. After the impulse test, the cable sample shall be subjected to ambient temperature to a power frequency voltage test at 2.5 Uo for 15 minutes No breakdown of the insulation shall occur.

II. Type Tests on Cable Compounds: The non-electrical type tests and type tests to check that the materials used for the

cable components have satisfactory properties shall be carried out as detailed in IEC 840.

The method of tests and test results should satisfy the requirement of IEC 840. D- Electrical Tests after Installation: (Site Tests): 1. Insulation: Tests on new installation are made when the installation of the cable and its

accessories has been completed.

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1.1 DC Testing: A DC voltage equal to 3 Uo shall be applied for 15 minutes. 1.2 AC Testing: As an alternative to the DC test an AC voltage test at power frequency in

accordance with item a) or b) below, can be used: a. Test for 5 minutes with the phase to phase voltage (U) applied between the

conductor and the metallic screen. b. Test for 24 hours with the normal phase to earth voltage of the system (Uo). 2. Non-metallic sheaths: The non-metallic sheath shall be subjected to the site tests specified in IEC

publication 229.