The BKM3L series molded case circuit breakers with residual current protection are suitable for AC 50Hz power distribution networks with a rated insulation voltage of 1000V, a rated operating voltage up to 400V, and a rated current up to 800A. They are used to distribute electrical energy and protect lines from damage caused by overload, short circuit, undervoltage, and other faults. Circuit breakers with a rated current of 630A and below can also be used for infrequent starting of motors. They can also be used to prevent fire risks caused by ground fault currents resulting from equipment insulation damage. These circuit breakers can be installed vertically or horizontally. This series of circuit breakers has an isolation function. This series of circuit breakers conforms to the following standards: IEC 60947-1 and GB/T 14048.1 "Low-voltage switchgear and controlgear - Part 1: General"; IEC 60947-2 and GB/T 14048.2 "Low-voltage switchgear and controlgear - Part 2: Circui