Patent ID: 6813131
Filing Date: 2004-11-02
Classification: H01H,H02H

Abstract:
A circuit breaker comprising:separable contacts; a latchable operating mechanism including a latch member which when released opens said separable contacts; a bimetal in series with said separable contacts and adapted for heating by current flowing therethrough, said bimetal including a temperature, a temperature coefficient, a first terminal, and a second terminal having a voltage, said bimetal being adapted to deflect by said heating, said bimetal coupled to said latch member to release said latch member in response to a persistent overcurrent condition; and a trip assembly comprising: a thermistor adapted to respond to the temperature of said bimetal, an amplifier having a first input, a second input and an output, a first resistor electrically connected between the second terminal of said bimetal and the first input of said amplifier, a second resistor electrically connected in parallel with said thermistor, a third resistor electrically connected in series with the parallel combination of said second resistor and said thermistor, with the series combination of said third resistor and the parallel combination of said second resistor and said thermistor being electrically connected between the first input of said amplifier and the output of said amplifier, the second input of said amplifier being referenced to the first terminal of said bimetal, the output of said amplifier having a voltage which is compensated for the temperature coefficient of said bimetal, means for providing a trip signal as a function of said compensated voltage, and means for releasing said latch member to trip said separable contacts open in response to said trip signal.