Application ofMCCB(EM) GAICA Moulded Case Circuit Breaker (named as MCCB in the following) is the 4th rising professional circuit breaker division, EM series MCCB is a new type breakerwhich is applied with rated insulating voltage 800V (500V for EM63), rated working voltage 690V and used for infrequent exchange and startup in AC(60) Hz condition. The MCCB is of protecting in overload, short-circuit, and under voltage situation to protect circuit system and power device from damage. The MCCB can be divided into B, N, S, H types according to their rated limit short-circuit breaking capacity. The MCCB is advantageous for its compact body, high breaking capacity (some even on flying arc), short arc-casting and superior aseismatic function. The MCCB has function of insulation with its mark. The product complies with IEC60947-2, GB14048.2.