Circuit breaker with metal melt isolation device

摘要

An insulated container of a circuit breaker is divided into three vertically-arranged portions including a case, a middle case, and a cover. A fixed contact shoe and a movable contact shoe are accommodated in the case. An opening and closing mechanism and an overcurrent trip device are accommodated in the middle case. A holder slidably passing through a hole in a bottom wall of the middle case by an operation of the opening and closing mechanism is moved linearly and perpendicularly to the bottom wall to open and close the movable contact shoe. A gap in the hole between the holder and the bottom wall is very small due to the straight movement of the holder, so that an arc gas generated in the case is completely shut down by the bottom wall and does not reach the opening and closing mechanism in the middle case during current interruption.