FAULT CURRENT DETECTING CIRCUIT

摘要

The present invention is designed to provide a high fault current detecting circuit capable of improving the detecting precision of a fault current exceeding a rated current of a circuit breaker and simultaneously improving the reliability as a result of the precise detection of a surge current. The high fault current detecting circuit according to the present invention comprises: a first current transformer for detecting a current flowing in a power circuit of a power system and outputting a current detecting signal; a pair of second current transformers for converting the current detecting signal provided by the first current transformer into each of the second conversion signals of a small current; a fault detecting circuit part for determining the generation of a fault current in the power circuit by comparison of a current value for indicating a second conversion signal output by any one of a pair of the second current transformer and the predetermined reference current value, and outputting a fault detecting signal at the time of determining the generation of the fault current; a surge detecting circuit part for determining the generation of a surge current in the power circuit by comparison of a current value for indicating a second conversion signal output by the remaining one of a pair of the second current transformer and the predetermined reference current value, and outputting a surge detecting signal at the time of determining the generation of the surge current; and a trip determination part for extracting a trip control signal at the time when at least one of the fault detecting signal and the surge detecting signal is received.