MRR1 Rotor Earth Fault Relay (MRR1D)

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Product number: MRR1D


The generator rotor protection relay MRR1 com-bines rotor earth fault protection, excitation overand undercurrent protection as well as rotating diode failure protection. Thus providing a powerful protection regarding the rotor of synchronous generators, covering the following ANSI codes:

  • 37 DC undercurrent relay

  • 40 Field relay

  • 58 Rectification failure relay

  • 64 Ground detector relay

  • 76 DC over current relay

The MRR1 is recommended for synchronous generators and motors above 1 MVA rating. The rotor earth fault element detects high and low resistance earth faults of the rotor winding.

It is equipped with two stages, one for alarm, one for trip. The excitation current protection element supervises the DC excitation current of brushless excitor machines.

The protective functions are: Undercurrent, overcurrent and ripple detection for diode failure protection.

  • 19“ racks – fully withdrawable

  • Door mounting – withdrawable and sealable

  • Panel mounting – fully withdrawable

  • Fault / disturbance recorder

  • Intuitive HMI

  • Display (of primary values)

  • Easy setting software – Smart view

  • Compact form factor

Protection of electrical (HV, MV) synchronous generators against:

  • Underexcitation damages (field failure protection, ANSI / IEEE C37.2: 40)

  • Stator Earth Fault / insulation damages

  • Rotor Earth fault detection

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