Torgeek
What is an IDMT relay?
IDMT relay is inverse definite minimum time relay. It is one in which Time of operation is inversely proportional to magnitude of fault current near pickup value and becomes substantially constant slightly above the pickup value of the Relay.
How do you calculate relay operating time?
Finally that operating time of relay would be multiplied with time setting multiplier, in order to get actual time of operation of relay. Hence say time setting of the relay is 0.1. Therefore the actual time of operation of the relay for PSM 10, is 3 × 0.1 = 0.3 sec or 300 ms.
What is the PSM of IDMT relay?
An IDMT relay is used to protect feeder through 500/1 CT. The relay has a PSM 100% and TMS = 0.4, relay characteristics are given for TMS = 1.
