DEIF's loss of mains relays protect generators against damage resulting from a non-synchronised reconnection to the grid after a temporary mains failure.
A mains failure will be detected, provided a disconnection at an arbitrary point of the network results in a swift change of the generator frequency (vector shift). An opening signal is then transmitted to the mains circuit breaker, and the generator will thus be protected against damages caused by an automatic reconnection to the high-voltage network.
- Vector shift
- Vector shift and df/dt (ROCOF)