RGM30 MCCB circuit breaker, applied in the circuit of AC 50 Hz (or 60Hz), the rated isolating voltage is 690V and the rated working voltage is below 600V, the rated current is under 630A ,which is used for the infrequently switching and starting the electromotor. The MCCB protects the overloading circuit to prevent the circuit and the power equipment from damage. The MCCB complies with the standard of GB 14048.2 idt IEC 60947-2.