GAS-BLAST CIRCUIT BREAKER

摘要

PROBLEM TO BE SOLVED: To find troubles of a reed switch used in a gas flow detecting circuit. SOLUTION: The gas-blast circuit breaker is equipped with a gas flow detecting circuit 1 comprising a reed switch 2 and a pull-down resistor 3 to detect variation of magnetic force of a magnet moved by flow of gas, and output ON/OFF of the reed switch 2 as a flow signal A, and a voltage detecting IC 5 for measuring a voltage B divided by the resistance of the pull-down resistor 3 and the contact resistance of the reed switch 2 at the turn-on time. The voltage detecting IC 5 built in an abnormal detection circuit 4 outputs a detection circuit abnormality signal C to a microcomputer 6.