VOLTAGE TRIP APPARATUS OF A MOLDED CASE CIRCUIT BREAKER

摘要

PURPOSE: A voltage trip apparatus of a molded case circuit breaker is provided to enhance the reliability of a molded case circuit breaker by breaking an application of an overvoltage through the detection of an input voltage level. CONSTITUTION: A transistor(Q1) is connected to an output terminal of the bridge diodes(D1-D4). The anode of a zener diode(ZD1) is connected to the collector and the base of the transistor(Q1) through a resistor(R2) and the cathode of the zener diode(ZD1) is connected to the ground. A trip coil is connected in paralleling with a capacitor(C1). An operational amplifier compares an output of the transistor(Q1) with a reference voltage(Vref) and outputs a high signal in case that the output voltage is larger than the reference voltage. An SCR is turned on to ground the output of the transistor(Q1).