| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit breaker with a prior alarm wherein an appropriate prior alarm announcement can be carried out by reducing the difference between actual load current and prior alarm pickup current value. SOLUTION: The circuit breaker is provided with a prior alarm means 10 by which an alarm is issued when a switching-on current exceeds a pickup current value set beforehand, and a maximum current measuring means 11 in which a running average current value of a real switching-on current is measured to store and retain its maximum value, and the current value based on the maximum running average current value stored and retained at a prescribed interval is taken as a new pickup current value. Furthermore, in the case the new pickup current value exceeds the rated current value of the circuit beaker, the pickup current value is taken as the rated current value to issue another alarm different from the prior one. COPYRIGHT: (C)2004,JPO
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