A study on compact shunt release device of MCCB using a voltage detecting circuit with hysteresis

MCCB(Molded Case Circuit Breaker) is widely used in power distribution systems for protecting an electrical circuit from damage caused by overload or short circuit. The shunt release device, an internal accessory of MCCB, opens the mechanism in response to an externally applied voltage signal. The shunt release device consists of an actuator and a control circuit. The conventional shunt release device has two bodies for each part. In order to make it one, the compact actuator and a voltage detecting circuit with hysteresis are developed. To minimize the size and improve performance, the electromagnetic force of compact Actuator has been analyzed by means of Maxwell. This analytic model is validated by comparing the simulation results and the experimental results. The voltage detecting circuit with hysteresis consists of input, hysteresis, output, reference, signal circuit and transistors. It estimates the level of input voltage without additional power source. In this paper, compact shunt release device with voltage detecting circuit with hysteresis is introduced. The compact shunt release device makes it possible for installing maximum quantity of MCCB in a panel. We found that performance and operation reliability was improved compared to the conventional shunt release device.