A power system is an interconnection of electric power stations by high voltage power transmission lines. Nowadays the electricity is transmitted over long distances and the length of transmitting power lines varies from area to area. A wire system is termed a power line on case it has no parallel branches and a power network in case it has parallel branches. According to their function, power lines and networks are subdivided into transmission and distribution lines. Transmission lines serve to deliver power from a station to distribution centres. Distribution lines deliver power from distribution centres to the loads. Lines are also classed into: 1) overhead; 2) indoor; 3) cable. Overhead lines comprise line conductors, insulators, and supports. The conductors are attached to the insulators, and these are attached to the supports. The greater the offered resistance, the higher are the heating losses in the conducting wires. The losses can be reduced simple by using a step down transformer. Indoor lines include conductors, cords, and buses. A conductor may comprise one wire or a combination of bare wires not insulated from one another. They deliver electric current to the consumer. As to underground lines, they are suitable for urban areas. Accordingly, they are used in cities and in the areas of industrial enterprises.A power system