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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)
  • Vector shift and df/dt (ROCOF) 
  • Detection of vector shift
  • ANSI code 78
  • Mains disconnection on mains failure
  • Ensures no asynchronous reconnection
  • LED indication of fault condition
  • LED indication for activated relay
  • 35 mm DIN rail or base mounting

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