Pole Mounted Substations

Pole Mounted Substations

It is nothing but outdoor substation with overhead installation of substation equipments. This is the cheapest substation for voltages upto 11 kV since it does not require any building work. The layout and schematic of pole mounted substation is shown in Fig. 8.6.1.

It consists of 11 kV line connected to the transformer through gang isolator and fuse. On H.T. side there is lightning arrester for protection of substation against lighting strokes. The transformer steps down the voltage to 400 V between the line. In the event of fault the oil circuit breaker on L.T. side isolates the transformer from the consumers. In pole mounted substations the transformer used has the capacity upto 200 kVA. It should be noted that the dielectric strength of oil in the transformer must be periodically checked. The gang isolator and oil circuit breaker should be shunt off in case of repair  of transformer. The secondary of transformer has 3 phase, 4 wire system to supply single phase as well as three phase loads.

Review Question

1. Explain pole mounted substations with a neat layout.