Main Substation

On the right hand side you can see the transmission line feed into a transformer. Such facilities, which accept power from transmission lines are referred to as Main Substations. A transmission line supplies dozens of such substations.

In the figure shown here, the main substation consists of the following:

B4: High voltage side breaker

B3: Low voltage side breaker

T2: Step down transformer

Transformer T2 is designed to reduce the incoming voltage from 220kV to 13.8kV.

Transformer T2 supplies 13.8kV power to a set of heavy conductors, which are generally known as the “13.8 kV bus”.

13.8 kV Motors

This system is provided with two motors which require 13.8 kV voltage to operate. Notice two motors are supplied with 13.8KV electric power through the breakers B5 and B6.