Power Cable Specifications

Power cables are mainly used for power transmission and distribution purposes. It is an assembly of one or more individually insulated electrical conductors, usually held together with an overall sheath. The assembly is used for transmission and distribution of electrical power.

The current carrying capacity is an important aspect is the selection of the optimum size of the conductor. Voltage drop and short rating is also a very important aspect to select the economical and optimum size of conductor. The safe current carrying capacity of an underground cable is determined by the maximum permissible temperature rise. The cause of temperature rise is the losses that occur in a cable which appear as heat.

It happens frequently that the conductor size necessary for installation is dictated by its ability to carry short-circuit current rather than sustained current. During a short-circuit, there is a sudden inrush of current for a few cycles followed by a steadier flow of current for a short period until the protection switchgear operators, normally between 0.1 – 0.3 seconds.