What is the instantaneous trip feature of a standard ground fault relay designed to have in terms of time delay?

The instantaneous trip feature of a standard ground fault relay is designed to have a time delay of 1.5 cycles. This specification is critical because it allows for a rapid response to ground fault conditions, which can help to minimize the potential for equipment damage and enhance safety by quickly disconnecting the electrical supply before extensive fault currents can cause harm.

Being set at 1.5 cycles, the relay provides a balance between being fast enough to protect against immediate hazard while still allowing for the possibility of temporary or transient faults that may not require disconnection. The importance of this timing ensures sensitive equipment is not unnecessarily shut down, thereby minimizing disruptions in service.

The choice of 1.5 cycles aligns with industry standards, enabling the relay to operate efficiently in recognizing ground faults while providing sufficient response time for protection.