MULTI-POLE CIRCUIT BREAKER WITH MULTIPLE TRIP BARS

摘要

This concerns a four pole molded case circuit breaker having separable main contacts and an operating mechanism utilized to cause the separable main contacts to open and close. A trip unit is provided to actuat e the operating mechanism in desirable circumstances. The circuit breaker in this case has four-poles, one of which is a neutral pole. The circuit breaker trip unit has rotatable trip bars therein, one of which is associate d with the three-line terminals and one of which is associated with the neutra l terminal. If the line terminal trip bar is actuated to move because of a fau lt to overload in one of the line terminals, only the line terminals will open because the neutral trip bar will not be moved. However, if the neutral trip bar is moved because of a predescribed neutral current value in the neutral conductor all of the contacts including the neutral contact will be opened because of the interlocking arrangement between the neutral trip bar and the line trip bar.