DEWA 1513403-R0 22kV 11kV XLPE Cables (2).pdf

8/10/2019 DEWA 1513403-R0 22kV 11kV XLPE Cables (2).pdf

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22/11 KV XLPE CABLES

PART VI

(SPECIFICATION )



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22&11kV XLPE Cables 1.5.1.3.4.03-Rev.0

Dubai Electricity & Water Authority 1 of 10 All Rights are reserved

LIST OF CONTENTS FOR TECHNICAL SPECIFICATIONS FOR


INDEX

SECTION TITLE

1. SCOPE

2. APPLICABLE STANDARDS

2.1 International Standards2.2 Internal Standards

3. DESIGN AND CONSTRUCTION3.1. Conductors3.2. Conductor Screen3.3. Insulation3.4. Insulation Non-metallic Screen

3.5. Insulation Metallic Screen3.6. Water Sealing3.7. Armour Bonding3.8. Armour3.9. Over sheath3.10. Extrusion3.11. Core Identification

3.12. Laying-up3.13. Embossing

3.14. Overall Dimensions

4. COMPONENTS AND ACCESSORIES

5. OPERATIONAL REQUIREMENTS

6. MAINTENANCE REQUIREMENTS

7. TYPE, ROUTINE AND FACTORY ACCEPTANCE TESTS7.1. Type Tests7.2. Routine Tests7.3. Factory Acceptance Tests7.4 Physical inspection of cable, drum and packing

8. COMMISSIONING REQUIREMENTS AND TESTS

8.5. Tests After Laying

9. TOOLS AND ACCESSORIES9.1. Cable length9.2. Sealing and Drumming

10. RATING AND DATA SHEET10.1. Data Sheet for 11kV Cables

10.2 System10.3 Design Criteria10.4 Type of Cables10.5 Construction10.6 Data Sheet for 22kV Cables


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1. SCOPE

Para (1) This section details technical specification of XLPE insulated power cables for nominalsystem voltage of 11 and 22 kV.

2. APPLICABLE STANDARDS

2.1 International Standards

Para (2) Except where modified by this specification, cable shall be designed, manufactured, and

tested in accordance with the latest edition of IEC 60502-2 publication includingamendments and other publications quoted in these Standards.

IEC 60060 High Voltage Test Techniques - Part I: General Definitions and TestRequirements.

IEC 60183 Guide to the selection of high voltage cables.

IEC 60228 Conductors of insulated Cables

IEC 60230 Impulse Tests on Cables and their Accessories.

IEC 60502-2 Power Cables with extruded insulation and their accessories for ratedvoltages from 1kV (Um = 1.2 kV) upto 30 kV (Um = 36 kV) -Part 2:Cables for rated voltages from 6kV (Um = 7.2 kV) upto 30 kV (Um = 36

kV).

IEC 60502-4 Power Cables with extruded insulation and their accessories for ratedvoltages from 1kV (Um = 1.2 kV) up to 30 kV (Um = 36 kV) -Part 4:Test requirements on accessories for cables with rated voltages from 6kV (Um = 7.2 kV) up to 30 kV (Um = 36 kV)

IEC 60811 Common test methods for insulating and sheathing materials for electric

cables.

IEC 60885 Electrical test methods for electric cables.

IEC 60986 Guide to the short circuit temperature limits of electric cables with arated voltage from 1.8/3 (3.6) kV to 18/30 (36) kV.

IEC 60287 Electric Cables - Calculation of the current rating

2.2 Internal Standards

Site and system operating conditions as per Design Criteria 1.1.0.0.0.01

General Technical Requirements for equipment as per 1.2.1.0.0.01.

General quality assurance requirements for Equipments as per 1.3.1.0.0.01.

Quality management system as per ISO 9001

3. DESIGN AND CONSTRUCTION

Para (3) This specification covers the following types of cables:

Single core unarmored cables

Three Core armored cables.

Para (4) Water protection cover over individual core.


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Para (5) Easy to remove water barrier tubes / semi-conducting / insulation by special tools

Para (6) Design and construction data for each type of cable is given in 'Data Schedule for Cables inEnclosure-1.

Para (7) Three core cable with circular, stranded copper/aluminiumconductors with triple extrudedconductor screen, insulation and insulation screen of which conductor and insulation screenare of semi-conducting materials and insulation is of dry vulcanized cross linked

polyethylene, all the individual cores laid up with non-hygroscopic Fillers, individualmetallic screens of copper tape and/or wires, armored with a single layer of galvanized steel

wires and PVC/PE sheathed overall suitable for6.35/11 (12) and 12.7/22(24) KV workingvoltage manufactured generally in accordance with IEC Publication 60502.

Para (8) Water sealing of conductors and longitudinal and radial water sealing along the metallicscreen is applied.

Para (9) The following conductor sizes are covered by this specification: -

Type-1: 300sq.mm, Copper

Type-2: 300sq.mm, Aluminium

Type-3: 240sq.mm, Copper

Type-4: 240sq.mm, Aluminium

3.1. Conductors

Para (10) The conductors shall be stranded compacted circular construction. Conductor materialshall be annealed copper or aluminium with cross section as specified in Specific

Requirements and shall conform to class 2 of IEC 60228 Specifications. The wire beforeshaping shall be smooth, uniform in quality, free from scale, inequalities, spills, splits and

other defects.

3.2.

Conductor Screen

Para (11) The conductor screen shall consist of an extruded semi-conducting compound. Thescreen shall fill the interstices between the outer individual strand wires forming the

conductor and provide a smooth, regular interface to the insulation layer. The extrudedsemi-conducting compound shall be firmly bonded to the insulation.

3.3. Insulation

Para (12) Insulation shall be extruded cross-linked polyethylene (XLPE), which shall be appliedusing a dry cure process designed to eliminate micro voids in the insulation.

Para (13) The tenderer shall furnish separately material properties of XLPE as listed below:

Physical properties

Electrical properties

Aging properties

Anti hygroscopic properties

Heat distortion properties

Certificates of origin from Raw Material Manufacturers

Para (14) The average thickness of the insulation, when determined by the method described inIEC 60811 shall not be less than the value stated in IEC 60502-2. The thickness at any

place may, however, be less than the specified nominal value provided that the differencedoes not exceed the limit specified in IEC 60502-2. The thickness of the semi-conductingscreen on the conductor or over the insulation shall not be included in the thickness of the

insulation.


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3.4. Insulation Non-Metallic Screen

Para (15) The insulation screen shall consist of a layer of extruded semi-conducting compound,having a minimum thickness of 1.0 mm, compatible with insulating material. The screenshall be designed to be easily stripped without damaging the insulation or leavingconducting material on the insulating surface.

Para (16) An insulation screen that requires heat for its removal is not acceptable.

Para (17) The insulation screen shall be applied directly upon the core insulation in a mannerensuring a uniform voltage stress across the insulation along the length of the cable.

3.5. Insulation Metallic Screen

Para (18) The metallic screen shall consist of a layer of copper tape and/or layer of annealed barecopper wires. Metallic screen shall be applied on 3 individual screens, one on each core.Layers of copper tape shall have a minimum of 15 percent overlap.

Para (19)

Effective cross-sectional area of three individual metallic screens shall be such that these(metallic screens) in combination with Armour shall be suitable for withstanding an earthfault current and duration as per 'Data Schedule for cables- Enclosure-1.

3.6. Water Sealing

Para (20) Cables shall be provided with water sealing of conductor and longitudinal and radialwater sealing along the metallic screen as described below:

Para (21) The conductor water sealing shall consist of a swelling material provided betweenconductor strands which turns into a jelly when comes in contact with water.

Para (22) The longitudinal water sealing along the metallic screen shall be provided by a swellinglayer applied under and over the metallic screen, or by a swelling material provided

between metallic screen wires as applicable.

Para (23) The swelling layer to be provided under the metallic screen should be semi conductiveand compatible with the extruded insulation screen and the metallic screen.

Para (24) The radial water sealing shall be provided by:

An extruded corrosion resistant metallic sheet (corrugated if required) or

Extruded PE (Polyethylene) applied over metal laminate.

Para (25) Radial water sealing is to be provided on individual cores

3.7. Armour Bedding

Para (26) An extruded bedding of PVC type ST2 shall be applied over the three-core assembly.

Interstices formed between the cores shall be substantially filled.

3.8. Armour

Para (27) The Armour shall consist of a single layer of galvanized round steel wires of appropriatesize conforming to the requirements of BSEN 10257-1&2: 1999.

Para (28) Alternatively, galvanized flat steel wires may be proposed. The tenderer shall indicate theapplicable standard including the test methods and acceptance criteria with respect to

sub-clauses. When joints in the Armour are necessary, they shall be brazed or welded andany surface irregularity shall be removed. A joint in any wire shall be not less than 1


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meter from the nearest other wire joint in the completed cable. The Armour wire mustcover the entire periphery.

Para (29) Provision of few copper wires in Armour in place of few galvanized steel wires toimprove conductivity will not be acceptable due to the risk of galvanic corrosion.

3.9.

Over sheath

Para (30) The over sheath shall be an extruded layer of polyethylene type ST7. An outerconducting coating shall be applied to the covering to serve as an electrode for the

voltage test on the over sheath.

3.10. Extrusion

Para (31) Conductor screen, insulation and insulation screen shall be applied by triple extrusionprocess.

3.11. Core Identification

Para (32)

The cores shall be identified in a distinct manner either by color (Red, Yellow and Blue)or by number (1, 2 and 3).

3.12. Laying-up

Para (33) Three individual cores shall be laid-up in a right hand direction of lay. Where necessary,

non-hygroscopic fillers shall be employed to form a compact and circular cable.

3.13. Embossing

Para (34) The over sheath shall be embossed in English along two lines equally spaced around thecircumference of the cable with the name of the Manufacturer, year of manufacture, type

of insulation (XLPE), number of cores, conductor size and material followed by thedetails given below:

DEWA ELECTRIC CABLE 11 000 V Contract No. CE/...../.... for 11 kV cable

DEWA ELECTRIC CABLE 22 000 V Contract No. CE/...../.... for 22 kV cable

Para (35) The letters and figures shall be raised and shall consist of upright block characters. Themaximum size of the characters shall be 13 mm. and the minimum size 15% of theappropriate overall diameter of the cable or 3 mm. whichever is the greater. The gapbetween the end of one legend and the beginning of the next shall not be greater than 150

mm.

Para (36) The extruded over sheath shall also be marked on the circumference of the cable

indicating cumulative marking of length of cable wound on the drum. Such markingstarting with "000" on the inner end of cable shall be made at interval of 1 or 10 meters.The marking on outer end of cable shall indicate in integer the actual length of the cableon the drum. The inner as well outer end of cable brought out on the drum flange shall

be clamped in such a manner to make the cable length marking easily visible.

3.14. Overall Dimensions

Para (37) The overall diameter of the manufactured cable shall not be more than 5% of theguaranteed value indicated by the Tenderer in his offer.

4. COMPONENTS AND ACCESSORIES

Para (38)

Nil


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5. OPERATIONAL REQUIREMENTS

Para (39) Nil

6. MAINTENANCE REQUIREMENTS

Para (40)

Nil

7. TYPE, ROUTINE AND FACTORY ACCEPTANCE TESTS

7.1 Type tests

Para (41) All electrical (clause 18) and non-electrical (clause 19) type tests applicable to 22 kVgrade XLPE insulated cable as specified in IEC 60502-2 shall be carried out, includinglongitudinal water tightness test (both conductor and metallic screen) in accordance withIEC 60502-2 (clause 19.22) and its Annexure-D. Radial water tightness of the cable shall

be demonstrated by a suitable test to be proposed by the Tenderer.

Para (42) However, these type tests need not be repeated under the contract if the manufacturersubmits satisfactory test reports/certificates, acceptable to DEWA, on tests conductedpreviously on identical design and size of cable.

7.2 Routine Tests

Para (43) Routine tests shall be carried out on random samples selected by DEWA inspector(s).

The frequency of sampling shall be two lengths (drums) per 10 kms length of cable butlimited to minimum 2 lengths (drums) and maximum 8 lengths (drums) of cable perconsignment/lot.

Para (44) The following routine tests shall be carried out as per the requirement of IEC 60502-2.

Measurement of the electrical resistance of conductors (clause 16.2). Partial discharge test (clause 16.3).

High voltage test (clause 16.4).

Voltage test on over-sheath (25kV, d.c.).

Sample Tests

Para (45) Sample tests shall be carried out on cable samples selected at random by DEWAinspector(s). Minimum number of samples shall be 2 lengths (drums) or 20% of thenumber of lengths (drums) which ever is less and maximum of 8 lengths (drums) perconsignment.

Para (46) The following sample tests shall be carried out as per the requirement of IEC-60502-2:

Conductor examination (clause 17.4).

Check of dimensions (clauses 17.5 to 17.8).

Voltage test (clause 17.9).

Hot set test for XLPE insulation (clause 17.10).

Para (47) In addition to the above sample tests specified in IEC 60502-2, the following tests shouldbe carried out on samples selected as above, as per the requirements of standards

specified therein.

Para (48) Tensile Strength of Armour Wires: Galvanized steel Armour wires shall be tested fortensile strength. The tensile strength shall fall within the permissible range of 340 - 500N/mm2 and elongation at break shall be above the minimum permissible value of 10% as

specified in BS EN 10275-1&2.


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Para (49) Measurement of zinc coating of Armour Wires: Galvanized steel Armour wires shall betested to determine the mass of Zinc coating. Mass of Zinc coating shall be in excess of275 g/m2, the minimum specified in BSEN 10244-2.

7.3 Factory Acceptance Tests

Para (50)

Manufacturer shall complete the routine & sample tests as per the standard specified inthis technical specification on each type and size of cables and their test reports shall be

handed over to DEWA Engineer(s) for verification during witness test & inspection.

Para (51) Witness test and inspection shall be carried out as specified in Cl.8.1.1. 8.1.2 and Cl.8.2of this specification in the presence of DEWA nominated inspectors.

Para (52) Minimum of four length (drums) shall be tested for routine and special tests during thewitness test per day. Deviations, if any, in meeting this minimum requirement in testingshall be indicated in the list of deviations during tendering stage.

7.4 Physical inspection of cable, drum and packing

Para (53) Physical inspection shall be carried out to ascertain the compliance with the requirementsspecified in clause 7.13 (embossing), 9.1 (cable length) & 9.2 (drum dimensions &packing) of this technical specification.

Para (54) Manufacturer shall arrange/keep the whole cable appropriately, so that DEWA

inspector(s) can verify the compliance with the above requirements conveniently.

8. COMMISSIONING REQUIREMENTS AND TESTS

8.1 Test after laying

Para (55)

Test after laying is to be recommended by the manufacturer considering

recommendations from CIGRE WG.21.9 (Electra No.148 June 1993) and IEC 60502-2,subject to DEWA's approval.

9. TOOLS, SPARES AND ACCESSORIES

9.1 Cable Length

Para (56) The cables shall be supplied in nominal drum length within 5% tolerance. The nominal

length for 3Core, 300 and/or 240 sq. mm Aluminium conductor shall be 500 m andcopper Conductor cable shall be 325 meter. The gross weight of the cable drum shall notexceed 7500 kg.

9.2 Sealing and Drumming

Para (57) Before dispatch, the manufacturer shall cap the ends of all cables so as to form a seal to

prevent the ingress of water during transportation, storage and installation. The cableshall be supplied on stout wooden/ steel drums, which shall be designed so as to protect

the cable from damage. The drums shall be made from best quality batten, each havingthickness of not less than 40 mm Minimum overall thickness of each flange of the cabledrum shall be 80 mm. The lagging batten shall be secured at least with two nails of eachend in addition to steel bonding straps.

Para (58) No drum shall contain more than one length of cable. The overall dimensions of the cable

drum shall not exceed the following limiting values:

Outer distance between flanges: 1800 mm


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Diameter of the flanges: 3500 mm

Para (59) The cable shall be tightly wrapped on the cable drum and no turn shall be left loose.Both ends of the cable shall be adequately secured to the cable drum. Inner end of thecable shall be suitably fixed/gripped to the cable drum so that it will not come out during

cable laying operation. The cable shall be wrapped on drums of suitable diameter suchthat the radius of bend of the innermost layers is not less than the minimum radius of

bend stipulated for installation of the cable.

Para (60) No space shall exist between the adjacent layers of the cable and between the drumflange and the cable.

Para (61) Cable shall be wrapped with black polyethylene sheet inside the wood covering of drum.

Para (62) Central lifting hole of the cable drums shall be provided with a steel pipe and the inner

diameter of steel pipe shall be from 100 mm to 115 mm. The pipe shall be welded withsteel plates at both ends and these plates shall be duly secured to the flanges of the cabledrum with suitable size bolts. The pipe and the welded end plates shall be of robustdesign to withstand the weight of the cable drum during unrolling.

Para (63) Each drum shall bear a distinguishing number on the outside of the flanges andparticulars of the cable, i.e. voltage, length, conductor size, cable type and gross weight

shall also be clearly visible. The direction for rolling shall be indicated by an arrow.

Para (64) The size of shipping marks indicated in clause 7.3 of 'Conditions of Tendering' is notapplicable for cable drums due to limited space on cable drum flange. These marks shallbe minimum height of 7.5 cm.

10. RATINGS AND DATA SHEET

10.1 System data

Para (65)

(Replacing System Parameters data in document 1.1.0.0.0.01)

1. Nominal System Voltage 11 kV2. Conductor Short Circuit Current (kA) 23.53. Short Circuit duration (sec.) 14. Earth Fault Current (kA) *25

5. Earth Fault duration (sec.) *0.5(* For design of armour + metallic screen)

10.2 Design data

Para (66) (In addition to document 1.1.0.0.0.01)

1. Conductor normal operating temperature 90oC

2. Conductor overloading temperature 105oC

3. Conductor/Metallic Screen maximum short circuittemperature

250/200oC

4. Conductor and metallic screen temperature before shortcircuit earth fault respectively (max)

90/85oC

5. Laying depth in ground 0.9 meter6. Formation of single core cables Trefoil

7. Bonding Both ends8. No of 3 phase cables/groups in parallel * 1 or 2

9. Distance between cables/groups * 0.4 meter10. Laying conditions In ground / pipes /

ducts / racks(*Unless otherwise agreed with DEWA)


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10.3 Type of Cables

Para (67) Single core unarmoured or 3-core armoured

10.4 Construction

TYPE OF CABLE SINGLE CORE

CABLES

THREE CORE

CABLES

Sec.

Ref.

Features Individual Core Individual

Core

3 CoreAssembly

7.1 Conductor x x -

7.2 Conductor Screen x x -

7.3 Insulation x x -

7.4 Insulation Screen x x -

7.5 Metallic Screen x x -

7.6 Water Sealing: x x -

i) Conductor x x -

ii) Longitudinal (metallicScreen)

x x -

iii) Radial x x -

7.7 Armour bedding (**) - - x

7.8 Armour (**) - - x

7.9 Over sheath x - x

7.10 Extrusion x x -

7.11 Core identification - x -

7.12 Laying up - - x

7.13 Embossing x - x

7.14 Overall dimensions x - x

8.00 Inspection x - x

8.01 Work Tests x - x

x Applicable- Not applicable** When applicable

10.5 Data Sheet For 22 kV XLPE Cables

System (Replacing System Parameters data in document 1.1.0.0.0.01)

1. Nominal System Voltage 22 kV

2. Conductor Short Circuit Current (kA) 16

3. Short Circuit duration (sec.) 3

4. Earth Fault Current (kA) *6

5. Earth Fault duration (sec.) *1

A.

* For design of metallic screenDesign Criteria (In addition to document 1.1.0.0.0.01)

1. Conductor normal operating temperature 90 oC

2. Conductor overloading temperature 105 oC

3. Conductor/Metallic Screen maximum short circuit temperature 250/200 oC

4. Conductor and metallic screen temperature before Short circuit andearth fault respectively (maximum)

90/85oC

5. Laying depth in ground 0.9 meters

6. Formation of single core cables Trefoil

7. Bonding Both ends

8. No of 3 phase cables/groups in parallel * 1 or 2

B.

9. Distance between cables/groups * 0.4 meter


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10. Laying conditions In ground / pipes / ducts/ racks

* Unless otherwise agreed with DEWA

C. Type of Cables Single core unarmoredor 3-core armored

D. Construction

TYPE OF CABLE SINGLE CORE

CABLES

THREE CORE CABLES

Sec.Ref.

Features IndividualCore

IndividualCore

3 CoreAssembly

7.1 Conductor x x -

7.2 Conductor Screen x x -

7.3 Insulation x x -

7.4 Insulation Screen x x -

7.5 Metallic Screen x x -

7.6 Water Sealing:

i) Conductor x x -

ii) Longitudinal (Metallic Screen) x x -

iii) Radial x x -

7.7 Armour bedding (**) - - x

7.8 Armour (**) - - x

7.9 Over sheath x - x

7.10 Extrusion x x -

7.11 Core identification - x -

7.12 Laying up - - x

7.13 Embossing x - x

7.14 Overall dimensions x - x

8.00 Inspection x - x

8.01 Work Tests x - x

X Applicable- Not applicable

** When applicable

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