The SDL Series Residual Current Operated Circuit Breaker is suitable for low-voltage power networks with AC 50Hz, rated insulation voltage 690V, rated operating voltage 400V, and rated current 16A to 800A. In addition to the overload, short-circuit, and under-voltage protection functions of the SD Series, it also provides personal electric shock protection and equipment leakage protection, and can prevent fire hazards caused by ground fault currents due to insulation damage in equipment. It can be used for overload and short-circuit protection of motors and lines, and also for infrequent starting of motors and infrequent switching of lines. A variant that only provides leakage alarm without tripping is also available.