Why is DC Supply Used in Substations?

We all know that substation is all about AC current. But why do we need DC voltage in the substation? After some research, we have found an answer which we will share today with you. Today we will discuss why is DC supply used in substations?

Why do we need DC voltage in the substation?/Why is DC Supply Used in Substations?

  • Generally battery bank is used in substations for supplying DC voltage. A question must be occurring in your head, why DC voltage? Why not AC? Let us go to the explanation. 
  • The main reason behind DC supply in substations is the continuous power supply in the control circuit. DC is a reliable source for current supply because we can get it from the battery. It will continuously supply electricity till it’s not discharged. The battery can store electricity power. So it is used for a backup power supply.
  • A control circuit has so many ON circuit breaker, isolator, and relay in the substation for the switchgear system. 

What is the problem if we use AC supply?

  • We can’t get AC supply from the battery and if power trips we can’t get power supply in the control circuit. 
  • If a power trip occurs and all of the devices shut down we can not test fault in the circuit breaker or relay.
  • So, during the disconnection of power, we still need a continuous power supply in the control circuit. As we can only get a continuous power supply from the battery and the battery can only give DC supply, so every device in the control circuit is designed for supplying DC.
 why is DC supply used in substations?

 

Other uses 

  • In a substation or power station, DC supply is used for opening and closing circuit breaker, activating protective relay, isolator, indicator light, an alarm circuit, PLCC (POWER LINE CARRIER COMMUNICATION), panel, and control room emergency light.
  • Protective devices respond more immediately to DC supply compared to AC. 
  • The static design which needs a DC supply can be directly connected to the battery. But for AC supply rectifier circuit is needed.
  • The control circuit is made with many digital devices like digital displays, sensors, LEDs, etc. These devices need DC supply. So, for using DC supply in the control circuit, it needs fewer circuits.

Hope this article was helpful for you to understand why is DC supply used in substations?

If you have any queries about why is DC supply used in substations then you can ask in the comment section.

You can also read: Substation Three-Phase Single-Line Diagram Explanation