Figure 145: Earth-fault situation in an isolated network
Directional earth-fault protection in a compensated network
In compensated networks, the capacitive fault current and the inductive resonance
coil current compensate each other. The protection cannot be based on the
reactive current measurement, since the current of the compensation coil would
disturb the operation of the protection relays. In this case, the selectivity is based
on the measurement of the active current component. The magnitude of this
component is often small and must be increased by means of a parallel resistor
in the compensation equipment. When measuring the resistive part of the residual
current, the relay characteristic angle (RCA) should be set to 0 degrees and the
operation criteria to "IoCos" or "Phase angle".
illustrates a simplified
equivalent circuit for a compensated network with an earth fault in phase C.
1MRS758755 C
Protection functions
REC615 & RER615
Technical Manual
303
Содержание Relion REC615
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