General study of area supply methods

ELECTRIC POWER is usually delivered to the distributed loads of an area by superimposed voltage webs or networks. In general, the higher voltage webs are used to transmit power, whereas the lower voltage webs, which provide much denser area coverage, are used to distribute power. Connections are required between the webs, which consist of step-down transformers with the necessary switching and protective apparatus. There are three general methods of supplying the lower voltage networks: 1. Radial networks. Separate lower voltage networks, each of which is supplied from one step-down transformer location. 2. Integrated networks. Integrated lower voltage networks which are effectively one large network supplied from several step-down transformer locations. 3. Radial networks with emergency cutovers. Same as 1, except normally open ties are provided between the networks to make possible load transfers from one network to other networks under outage or emergency conditions.