Short circuit current rating for PVC & XLPE cables

Short Circuit Rating are based on the assumption that duration of the short circuit is to small and apparently that there is no transmission of heat, produced during short circuit, through the insulation and the whole of it is absorbed by the conductor. With a high increase in KVA, capacity in power distribution system, cables are expected to carry short circuit to carry short circuit current of high magnitude. Normally rated at 70 C,PVC insulation material permit a short circuit temperature of160 C.

T: Duration of Short Circuit in seconds.

A: Area of Conductor in Sq.mm.

K: Constant

For Copper with general purpose PVC Insulation- 0.115

For Copper with Heat Resisting PVC Insulation- 0.104

For Copper with XLPE Insulation- 0.143