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FIELD GROUND FAULT DETECTOR AND FIELD GROUND FAULT RELAY FOR DETECTING GROUND FAULT CORRESPONDING TO DC COMPONENT EXTRACTED FROM GROUND FAULT CURRENT
FIELD GROUND FAULT DETECTOR AND FIELD GROUND FAULT RELAY FOR DETECTING GROUND FAULT CORRESPONDING TO DC COMPONENT EXTRACTED FROM GROUND FAULT CURRENT
The field fault detector connects a predetermined resistor in series with a predetermined DC voltage and supplies a DC voltage between the N-side field circuit of the generator and the ground through this resistance. The voltage across the resistor is input to the low pass filter. The output stage voltage between the N-side field circuit and the ground is input to another low pass filter. The voltage output from each low pass filter is input to the level ratio determination circuit. The level ratio determination circuit outputs the ground fault detection result to the outside based on these voltages. Therefore, even if the DC voltage fluctuates or the harmonic voltage of the thyristor-excited generator motor does not affect the ground fault detection angle.
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