Product Name: Rated Voltage 3.6/6～26/35kV for XLPE insulated power cable

For XLPE (cross-linked polythene) insulated power cable, either chemical method or physical method is employed to transform the molecular structure of PE (polythene) from chain into three-dimensional network, i.e. thermoplastic PE is transformed into thermosetting XLPE. After cross-linking, the thermal and mechanical properties of PE have been greatly improved while its excellent electrical property are still retained.
The maximum permissible operating temperature of the conductor of XLPE insulated power cable is 90℃ which resistance is higher than that of PVC (polyvinyl chloride) or PE insulated power cable. The cable has the advantage of simplicity in construction, lightness in weight, convenience in application besides its excellent electrical, thermal, mechanical and anti-chemical corrosion properties. It can also be laid with no limitation of level difference along the route.

Standard:

Chinese standard GB/T12706-2002 “Extruded solid dielectric power cables for rated voltages from 1kV(Um=1.2kV) to 35kV (Um=40.5kV)”or IEC, BS, DIN and ICEA upon request.

Application:

The product is suitable for use in power transmission and distribution lines with rated power frequency voltage 3.6/6～26/35kV.

Operating characteristics:
Rated power-frequency voltage U0/U: 3.6/6～26/35kV
Max. Permissible continuous operating temperature of conductor: 90℃.
Max. temperature of conductor during cutting-out shall not exceed 250℃.(5S maximum duration)
The circumstance temperature under installation should not below 0℃.
The bending radius of a single-core cable should not less than 20 times of the cable diameter.
The bending radius of a three-core cable should not less than 15 times of the cable diameter.

Voltage Designation:
The rated voltage of the cable for a given application shall be suitable for the operating conditions in the system in which the cable is used, and is expressed in the form of U0/U（Um）kV.
U0——The rated power-frequency voltage between conductor and earth or metallic screen, for which the cable designed;
U ——The rated power-frequency voltage between conductors, for which the cable designed;
Um——The maximum value of the “highest system voltage” for which the equipment may be used.

The values of U0 recommended for cables to be used in three-phase systems are listed below:

Note: System category  A ——This category comprises those systems in which any phase conductor that comes in contact with earth or an earth conductor, is disconnected from the system within 1 min;
System category  B ——This category comprises those system which, under fault conditions, are operated for a short time with one phase earthed. This period should not exceed 1h. For a longer period, not exceeding 8h on any occasion can be tolerated. The total duration of earth faults in any year should not exceed 125h.;
System category  C ——This category comprises all systems which do not fall into categories A and B.

Description and Application:

Production Range:

Note: The single-core armoured cables are used for D.C system only, as for A.C system, non-magnetic armour material should be used or a magnetic isolation should be applied.

Technical Data：

D.C. resistance of conductor and conductor maximum short circuit current.

Current Carrying Capacity：

3.6/6～12/20kV XLPE insulated power cable

Note: The screen-copper-tape and steel wire (including all copper wire for magnetism separation) of single-core steel wire armoured power cable for AC system must be connected to earth well and effectively. 
The current carrying capacity is calculated by formulas of IEC. It is advised in the new edition of GB/T12706 that the current carrying capacity of steel wire armored power cable with special structure is lower than that in IEC standard, so the cross-section should be enlarged appropriately.

18/20～26/35kV XLPE insulated power cable:

Note: The screen-copper-tape and steel wire (including all copper wire for magnetism separation) of single-core steel wire armoured power cable for AC system must be connected to earth well and effectively. The current carrying capacity is calculated by formulas of IEC. It is advised in the new edition of GB/T12706 that the current carrying capacity of steel wire armored power cable with special structure is lower than that in IEC standard, so the cross-section should be enlarged appropriately.

Installation and Operation Condition:

Max. Rated temperature of the cable conductor：90℃.
Circumstance temperature in air：40℃.
Ground temperature：25℃.
Soil thermal resistivity：1.0℃.m/W.
Depth of laid：0.8m.
Single-circuit only: 
Single-core cable is installed in parallel. Adjacent space is equivalent to the diameter of the cable.

Rating factors of current carrying for different soil temperature:

Rating factors of current carrying for different thermal resistivity:

Rating factors of current carrying for different air temperature: