Earth-fault relay REJ 511

Basic protection of busbars and feeders in utility substations and industrial power distribution systems

Not active product since 2009

The earth-fault relay REJ 511 is a secondary relay which is connected to the current transformers of the object to be protected. The earth-fault unit continuously measures the neutral current of the object. On detection of a fault, the relay will start, trip the circuit breaker, provide alarms, record fault data, etc., in accordance with the application and the configured relay functions.

The earth-fault unit includes low-set stage I0 > and high-set stage I0 >>. If the high-set stage is given a setting value within the lower part of the setting range, the relay module will have two nearly identical stages. In this case, the relay can be used in two-stage load shedding applications.

The protection functions are independent of each other and have their own setting groups and data recordings. The earth-fault protection function uses conventional current transformer measurement.

An output contact matrix allows start or trip signals from the protection stages to be routed to the desired output contact.


  • Earth-fault protection relay is used as a secondary relay which is connected to the current transformers of the object to be protected

Product benfits

  • Flexible tripping and signalling facilities

Product features

  • Low-set non-directional earth-fault stage with definite time or inverse definite minimum time (IDMT) characteristic
  • High-set non-directional earth-fault stage with instantaneous or definite time characteristic
  • Circuit-breaker failure protection unit (CBFP)
  • Disturbance recorder
  • Continuous self-supervision

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