REG 316*4 1MRB520049-Uen / Rev. B ABB Switzerland Ltd
4-41
Rotor ground fault protection
The rotor ground fault protection injects a voltage with an ampli-
tude of 50 V and a frequency of 12.5 or 15 Hz to permanently
bias the potential of the rotor circuit in relation to ground. The
scheme signals a ground fault when the leakage resistance of
the rotor circuit falls below the value set on the protection.
The injection voltage of 50 V is supplied by the same injection
unit Type REX 010 and injection transformer unit Type REX 011
as are used for the stator ground fault scheme.
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