| 摘要 |
PROBLEM TO BE SOLVED: To provide an arc extinguishing device capable of extinguishing an arc at the time of interrupting a short-circuit current without needing a complicated contact structure and not requiring a loss, a radiator, a heat sink, or the like at all times. SOLUTION: A pair of arc running electrodes 5, 6 each having in its middle as an intermediate a PTC element 7 with a positive temperature coefficient of resistance are disposed near main contacts of a molded-case circuit breaker. Resistance of the PTC element sharply increases when the element temperature exceeds a fixed resistance transition temperature, and when an arc generated by opening the main contacts moves to the arc running electrodes 5, 6, the PTC elements 7 are heated to increase their resistance sharply, and as a result, arc sustaining conditions collapse to extinguish the arc.
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