What is the purpose of relay in substation? All Questions › Category: Switchgear And Protection › What is the purpose of relay in substation? 0 Vote Up Vote Down Chetan Shidling Staff asked 5 years ago I need short information. 2 Answers 0 Vote Up Vote Down Ashok answered 5 years ago Purpose of realy for protection of system. There are various types of relays. It sense the fault & give alarm to circuit breaker to trip the syatem. 0 Vote Up Vote Down chetan shidling answered 4 years ago The relay is a device which detects to fault and initiates the operated of a circuit breaker.