Which of the following terms defines the time taken by a protective relay to operate and initiate a trip after detecting a fault?

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Question

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RRB JE CBT 2 (Electronics Engineering) ReExam Official Paper (Held On: 04 Jun, 2025)

Answer 1

The term that defines the time taken by a protective relay to operate and initiate a trip after detecting a fault is operating time.

Explanation:

Operating time: This is the time interval from the moment the fault current reaches the relay's pick-up value until the relay's output contacts close (or operate) to initiate a trip signal to the circuit breaker. This is the crucial time delay for the relay itself.
Pick-up time: This refers to the time it takes for the relay's sensing element to respond and "pick up" or recognize that a fault condition exists, i.e., the fault current has exceeded a predefined threshold.
Reset time: This is the time taken for the relay to return to its normal, pre-fault state after the fault has been cleared and the fault current has fallen below the reset value.
Tripping time: This term can sometimes be used more broadly to refer to the total time from fault inception until the circuit breaker completely interrupts the fault current. It includes the relay's operating time and the circuit breaker's operating time. However, for the relay's action specifically, "operating time" is the precise term.