By using underground cable, the power is transmitted from the generating station to the consumers. When electrical power is unable to transmit by overhead lines or in a thickly populated area, underground cables are used. An underground cable consists of one or more conductor covered with suitable insulation and surrounded by a protecting core. Normally the number of cores in underground cables are 1, 2, 3, 3 ½ and 4.
Advantages of cables
i. Underground cables are not subjected to lightning discharges, thunder, storms, birds and other severe weather conditions.
ii) As there is no tension on the conductor, it will not break due to mechanical reasons after being installed. Hence there are very few chances for a power failure. It reduces accidents.
iii. Less maintenance is required.
iv. There is no interference with tele communication circuits.
Disadvantages of cables
i. The installation cost is high.
ii. High voltage cables are difficult to manufacture due to the insulation problem.
iii. Joining of underground cables is difficult.
iv. Fault location is not easy.