Patent ID: 6654217
Filing Date: 2003-11-25
Classification: H01H,H02H

Abstract:
A trip circuit for a circuit breaker having a tripping mechanism and a breaker pole, the trip circuit comprising:a sensor to determine a rate of change in the current level and generate a rate of change signal; a positive detector connected to the sensor to determine a positive current direction and generate a positive current signal; a negative detector connected to the sensor to determine a negative current direction and generate a negative current signal; a declining current inhibit circuit connected to the positive and negative detectors, the declining current inhibit circuit allowing the positive and negative detectors to generate the respective positive and negative current signal only when the current being measured is increasing in either a positive or negative direction from zero; an electronic switch connected to the tripping mechanism of the circuit breaker and the positive and negative detectors, the electronic switch activating the tripping mechanism of the circuit breaker as a result of receiving the positive current signal or negative current signal; a power supply connected to the tripping mechanism and the electronic switch; and a current limiter connected to the power supply and the tripping mechanism, the current limiter allowing an initial high voltage to activate the tripping mechanism quickly but subsequently limit the current to prevent damage to the tripping mechanism.