| 摘要 |
PROBLEM TO BE SOLVED: To enable response of arc failure protective function of high relibility, by generating a trip signal as the function of an amplitude wherein a series of pulses are accumulated and attenuated with time, and opening a contact capable of opening in response to the trip signal. SOLUTION: A circuit breaker 3 is equipped with an arc failure detector 23 in addition to a thermal-magnetic overcurrent equipment 15. The detector 23 is a trip circuit which responds to the inverse relation between the magnitude of the step type increase of a current generated at the time of arc generation in an electric system and the rate of arc generation. A pulse generating circuit 29 in the arc failure detector 23 generates a plus whose amplitude is a linear function of an arc current whenever the arc current is generated, and a series of pulses are generated. This series of pulses are accumulated and attenuated with time, and applied, as the function of an amplitude, to a capacitor 105 and a resistor 113 of a trip signal generator. Thereby a trip signal is generated, and a contact 11 capable of opening is opened in response to the signal. |
