SM1L series moulded case circuit break with residual current production. Rated insulation Voltage is 800V. It applies to circuit of AC 50Hz, rated working voltage 400V and rated working Current up To 630A, for infrequent switch over and infrequent start of motor. With overload, Short Circuit and under-voltage production, it can Protect circuits and power-supply equipment from damage, can also Be used for production from damage and any potential fire-hazard Caused by long Existing earth fault which can not be detected by Over-current production. The value of residual current is selectable.