SHORT CIRCUIT test

SHORT CIRCUIT

LOADING CAPACITY

The possible short circuit current which a cable will be subject to for a short time is dependent on the short circuit conductor of the circuit the connected short circuitry the damping apparatus e. g.

Transformer, Reactor etc and as well as the distance of the short circuit point from the generating station. The short circuit current should, therefore, be calculated for every point of the circuit. From this calculated short circuit current and the known switching-oft time? The cross-section can be determined" from the diagram illustrating the short circuit capacity for PVC cables up to voltage E/Eo=10/SB KV and various cross-sections.

Whereas the allowable conductor temperature for continuous full load operation are 70°C and 65°C tor cables up to 6KV and of 10KV respectively, the corresponding limiting temperatures of conductors at short circuit are 1t6O°C and 155°C. It is evident from the curve that the shorter the switching-oft time the smaller is the cross-section, the greater is the economy.