These relays are useful for protection of 3-phase AC induction motors against various hazards. With their unique advantages they eliminate use of a thermalbimetal relay for motor protection. Being current sensing, they are to be selected according to motor rating and are availablmore...
The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, over-voltage, reverse power flow, over- and under- frequency. Microprocessor-based digital protection rmore...