Over- and undervoltage relay REU 513

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

Not active product since 2009

The over- and undervoltage relay REU 513 is a secondary relay which is connected to the voltage transformers of the object to be protected. The unit continuously measure the fundamental wave of the phase-to-phase voltages of the object. On detection of fault, the relay will activate and trip the circuit breaker, provide alarms, record fault data, etc., in accordance with the application and the configured relay functions.

The overvoltage unit includes low-set stage U> and high-set stage U>> and the undervoltage unit low-set stage U< and high-set stage U<<. The high-set undervoltage stage can alternatively be set to evaluate the positive-phase-sequence voltage. In addition, the high-set undervoltage stage can be configured to evaluate only one instead of three phase-to-phase voltages.

The protection functions are independent of each other and have their own setting groups and data recordings. The over and undervoltage functions use conventional voltage transformer measurement.
An output contact matrix allows start or trip signals from the protection stages to be routed to the desired output contact.


  • Over- and undervoltage protection relay

Product benefits

  • Multi-functional protection relay

Product features

  • Single or three-phase use
  • Includes a high-set and low-set overvoltage unit, a high-set and low-set undervoltage unit and a circuit-breaker failure protection unit.
  • Disturbance recorder
  • Non-volatile memory
  • Continuous self-supervision

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