POWER CIRCUIT BREAKER WITH AIR GAP BETWEEN MOLDED INSULATIVE CASING AND GROUNDED BARRIER INSULATING OPERATING MECHANISM

摘要

A compact power circuit breaker (1) has a molded insulative casing (3) providing the structural support and electrical isolation for the pole mechanisms (11) mounted in cavities (9) in the casing and the operating mechanism (33) mounted to the front of the casing. A grounded barrier (17) between the pole mechanisms (11) and the operating mechanism (33) protects the operator actuating push bottons controlling the operating mechanism and accessible through a molded insulative cover. Preferably, the grounded barrier (17) is sandwiched between a rear section (5) of the molded casing containing the pole cavities and a forward section (7) to which the operating mechanism is secured. The grounded barrier (17) is connected to an electrically conductive pan (61) extending under the molded insulative casing which also houses electrically grounded linkages coupling the operating mechanism to the vacuum interrupters of the pole mechanisms. A vented air gap (65) between the rear section (5) of the molded insulative casing and the grounded barrier (17) minimizes erosion of the molded insulative casing in the event of an arc penetrating the casings to the grounded barrier.