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CU/XLPE/CAS/PE-76/132(145)KV
Grand Cable
Applicable Standard
IEC 60228
IEC 60840
Description
The cables shall be laid directly in ground except inside the premises of the Substations. Within the substations the cables shall be laid in covered concrete trenches supported on cable trays. The bidder shall submit cable sizing calculations to justify the cable selected and method of installation. The minimum size of the 132 kV cable required for this project is 400 sq. mm. The cable circuits shall be designed to transfer at least 2x120 MVA continuously.
For the purpose of calculating current carrying capacity, the ground temperature at one meter depth shall be taken as 30°C, average soil thermal resistivity 1.3 Km/W.
Cross bonding and transposition of cable will be mandatory wherever the route lengths facilitate proper sectioning of the cables. In the case of short route lengths, single point bonding or mid-point bonding will be allowed. All precautionary measures shall be taken to eliminate possibility of electric shock due the sheath voltage.
Rated Voltage
76/132(145) kV
Cable Construction
Conductor
The conductor shall be manufactured from stranded plain annealed copper and shall comply with the requirements of IEC Publications.
Both circular stranded and segmental Milliken designs are equally acceptable by mutual agreement.
Provision should be made to prevent the longitudinal penetration of water along the conductor. This is to be achieved by the application of a moisture barrier between the strands of the conductor. A radial water barrier alone over the conductor construction is not considered an acceptable solution.
Semi-Conducting Conductor Screen
The conductor screen shall be extruded and consist of a black, semi-conducting thermoset material fully compatible with the conductor and extruded insulation. The outer surface of the semi-conducting screen shall be smooth, cylindrical and firmly bonded to the overlying insulation.
A semi-conducting tape may be applied between the conductor and the extruded semiconducting screen. The tape shall be compatible with the conductor and the extruded screen material during operation of the cable.
Insulation
The insulation shall be an extruded cross linked polyethylene (XLPE) material forming a concentric dielectric surrounding the conductor.
Every effort is to be made by the manufacturer to ensure the purity of the insulation extruded on the cable core. Suitable sieves are to be employed to remove particulate contamination from the extruded material, which may affect the electrical performance of the cable insulation. The size of the holes within the sieve shall be less
than or equal to 100 micrometers.
The thickness of the insulation shall be specified as the minimum average value measured according to IEC Publication.
Insulation Screen
The insulation screen shall be extruded and consist of a black, semi-conducting thermoset material fully compatible with the extruded insulation. The interface between the insulation and the semi-conducting screen shall be smooth, cylindrical and firmly bonded.
Cushioning/Water Blocking Layer
The core shall be taped overall with semi-conducting cushioning tapes to prevent possible mechanical damage of the cable core caused by thermal expansion during normal operation of the cable.
Provision should be made to prevent the longitudinal penetration of water along the interface between the cable core and the metallic sheath by the application of suitable water swellable tapes applied over the cable core.
Anti-Termite Protection
Incorporated in the outer covering shall be brass or bronze tapes as a protection against termite attack.
Alternatively, a proven and environmentally acceptable anti-termite protection shall be considered.
The protection against termite attack of the cable insulation shall be by the application of two brass or bronze tapes, the first being applied with a 10% gap lap and the second tape to be similarly applied but registered centrally over the gap of the first tape.
Metallic Sheath
The cable core shall be protected overall by an extruded aluminum or lead alloy sheath. The sheath is required to fulfil the following requirements.
a) Provide a radial watertight barrier to the ingress of moisture into the extruded cable core.
b) prevent mechanical damage to the extruded cable core during installation and service.
c) provide protection against minor accidental damage caused by third party interference with cable during service.
d) Be capable of sustaining the specified earth fault currents for the time stipulated by the user.
e) Be capable of carrying the circulating current for solid bonded sheath systems without the operating temperature of the insulation and over sheath being exceeded.
Sheath
A layer of bituminous compound shall be applied to the metallic sheath to provide protection from corrosion.
The over sheath shall comprise an extruded layer of black, medium density polyethylene (MDPE) applied generally in accordance with IEC Publication.
A conducting resin coating is to be applied overall to enable the electrical integrity of the over sheath to be checked by the application of a dc. test voltage in the factory and after site installation of cables.
The outer covering for cables shall have been subjected to abrasion, penetration and saline bath tests during the type approval programme of tests and approved.
Dispatch
Both ends of the cable shall be rendered fully watertight by fitting and plumbing a metal end cap to both ends of the cable. The outer serving shall be sealed to the cap by taping or covering with a heat shrinkable sleeve.
A pulling eye shall be fitted to the leading end of the cable and to both ends if requested. The pulling eye shall form part of the end cap but shall also be bonded to the conductor, and be capable of withstanding a tension of 100N/mm2 of conductor area.
The cable shall be dispatched on drums of suitable construction with a minimum hub diameter of 15D (where D is the outer diameter of the cable).
The drum shall be enclosed by either adjacent fitting wooden battens or continuous metal cladding.
Applicable Standard
IEC 60228
IEC 60840
Description
The cables shall be laid directly in ground except inside the premises of the Substations. Within the substations the cables shall be laid in covered concrete trenches supported on cable trays. The bidder shall submit cable sizing calculations to justify the cable selected and method of installation. The minimum size of the 132 kV cable required for this project is 400 sq. mm. The cable circuits shall be designed to transfer at least 2x120 MVA continuously.
For the purpose of calculating current carrying capacity, the ground temperature at one meter depth shall be taken as 30°C, average soil thermal resistivity 1.3 Km/W.
Cross bonding and transposition of cable will be mandatory wherever the route lengths facilitate proper sectioning of the cables. In the case of short route lengths, single point bonding or mid-point bonding will be allowed. All precautionary measures shall be taken to eliminate possibility of electric shock due the sheath voltage.
Rated Voltage
76/132(145) kV
Cable Construction
Conductor
The conductor shall be manufactured from stranded plain annealed copper and shall comply with the requirements of IEC Publications.
Both circular stranded and segmental Milliken designs are equally acceptable by mutual agreement.
Provision should be made to prevent the longitudinal penetration of water along the conductor. This is to be achieved by the application of a moisture barrier between the strands of the conductor. A radial water barrier alone over the conductor construction is not considered an acceptable solution.
Semi-Conducting Conductor Screen
The conductor screen shall be extruded and consist of a black, semi-conducting thermoset material fully compatible with the conductor and extruded insulation. The outer surface of the semi-conducting screen shall be smooth, cylindrical and firmly bonded to the overlying insulation.
A semi-conducting tape may be applied between the conductor and the extruded semiconducting screen. The tape shall be compatible with the conductor and the extruded screen material during operation of the cable.
Insulation
The insulation shall be an extruded cross linked polyethylene (XLPE) material forming a concentric dielectric surrounding the conductor.
Every effort is to be made by the manufacturer to ensure the purity of the insulation extruded on the cable core. Suitable sieves are to be employed to remove particulate contamination from the extruded material, which may affect the electrical performance of the cable insulation. The size of the holes within the sieve shall be less
than or equal to 100 micrometers.
The thickness of the insulation shall be specified as the minimum average value measured according to IEC Publication.
Insulation Screen
The insulation screen shall be extruded and consist of a black, semi-conducting thermoset material fully compatible with the extruded insulation. The interface between the insulation and the semi-conducting screen shall be smooth, cylindrical and firmly bonded.
Cushioning/Water Blocking Layer
The core shall be taped overall with semi-conducting cushioning tapes to prevent possible mechanical damage of the cable core caused by thermal expansion during normal operation of the cable.
Provision should be made to prevent the longitudinal penetration of water along the interface between the cable core and the metallic sheath by the application of suitable water swellable tapes applied over the cable core.
Anti-Termite Protection
Incorporated in the outer covering shall be brass or bronze tapes as a protection against termite attack.
Alternatively, a proven and environmentally acceptable anti-termite protection shall be considered.
The protection against termite attack of the cable insulation shall be by the application of two brass or bronze tapes, the first being applied with a 10% gap lap and the second tape to be similarly applied but registered centrally over the gap of the first tape.
Metallic Sheath
The cable core shall be protected overall by an extruded aluminum or lead alloy sheath. The sheath is required to fulfil the following requirements.
a) Provide a radial watertight barrier to the ingress of moisture into the extruded cable core.
b) prevent mechanical damage to the extruded cable core during installation and service.
c) provide protection against minor accidental damage caused by third party interference with cable during service.
d) Be capable of sustaining the specified earth fault currents for the time stipulated by the user.
e) Be capable of carrying the circulating current for solid bonded sheath systems without the operating temperature of the insulation and over sheath being exceeded.
Sheath
A layer of bituminous compound shall be applied to the metallic sheath to provide protection from corrosion.
The over sheath shall comprise an extruded layer of black, medium density polyethylene (MDPE) applied generally in accordance with IEC Publication.
A conducting resin coating is to be applied overall to enable the electrical integrity of the over sheath to be checked by the application of a dc. test voltage in the factory and after site installation of cables.
The outer covering for cables shall have been subjected to abrasion, penetration and saline bath tests during the type approval programme of tests and approved.
Dispatch
Both ends of the cable shall be rendered fully watertight by fitting and plumbing a metal end cap to both ends of the cable. The outer serving shall be sealed to the cap by taping or covering with a heat shrinkable sleeve.
A pulling eye shall be fitted to the leading end of the cable and to both ends if requested. The pulling eye shall form part of the end cap but shall also be bonded to the conductor, and be capable of withstanding a tension of 100N/mm2 of conductor area.
The cable shall be dispatched on drums of suitable construction with a minimum hub diameter of 15D (where D is the outer diameter of the cable).
The drum shall be enclosed by either adjacent fitting wooden battens or continuous metal cladding.
