Differential relays are used to protect the equipment against (a) Internal faults, (b) Reverse Current, (c) Overvoltage, (d) Over Current

By BYJU'S Exam Prep

Updated on: October 17th, 2023

To guard against internal problems, the equipment is protected by differential relays. When the phasor difference of two or more similar electrical quantities exceeds a certain threshold, a differential relay will turn on. Therefore, a current differential relay is one that contrasts the current entering with the current exiting a certain system portion.

Differential relay:

  • The two currents are equal when everything is working properly, but this condition is no longer true when a fault happens.
  • The functioning coil of the relay is configured to pass through the difference between the incoming and departing currents.

Applications of Differential Relay

  • Differential relays are frequently employed to safeguard equipment from internal defects.
  • One type of differential relay used to safeguard the stator winding of an alternator against internal problems is the Merz price protection scheme.
  • The protection of transformer windings is another application for the differential relay.
  • Differential relays can be used to protect transmission lines and bus bars, among other things.


Differential relays are used to protect the equipment against (a) Internal faults, (b) Reverse Current, (c) Overvoltage,(d) Over Current

To safeguard the apparatus from internal failures, differential relays are used. The relay will activate and open the circuit breaker to isolate the defective portion if the differential current is greater than or equal to the pickup value.

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