Auto-monitoring System for Residual Current Circuit Breakers

Residual current circuit breakers (RCCBs) are used to provide electric shock protection, initial and periodical verification is necessary to check the effectiveness of RCCBs. This paper presents an auto-monitoring system with simple application circuit and low power consumption, which can test the function of the current transformer, silicon controlled rectifier (SCR), tripping solenoid, controller and other components of the residual current circuit breaker (RCCB) periodically. This test can be completed without disrupting power to the load or compromising normal function of the RCCB, and power denial or visual alarm can be provide after a fault is detected. A simulated residual current is generated periodically, and the response of these components is monitored by the system for functional verification. In this system, the signal that triggers the SCR is limited near the end of the positive half cycle of the hot line under the test mode, in accordance with the tripping characteristic of the RCCB, the functional verification will not disrupt the power to the load. Under the work mode, the signal that triggers the SCR is consistent with the tripping signal of the RCCB controller, guaranteeing the normal function of the RCCB. (c) 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.