ELECTRONIC OVERCURRENT DETECTION AND TRIPPING CIRCUIT

An electronic overcurrent detection and tripping circuit for circuit breakers is disclosed. The circuit includes an instantaneous trip circuit, a short time delay trip circuit, a long time delay trip circuit and a ground trip circuit. Each of the circuits is provided with adjustable ranges which can be set by suitable tap blocks or the like. A novel power supply is provided for the circuit which incorporates a unique series-connected zener diode and sensing resistor. The power supply circuit also provides sufficient power for tripping a magnetic latch of the circuit breaker whose current is being monitored. Each of the circuit functions can be disabled for purposes of tests by simply placing the function tap block pin in an appropriate test position.