Multipole medium voltage air circuit breaker - has housing whose design enables overpressure to increase light arc quenching, and has external actuator

摘要

The circuit breaker housing is a moulded case with a compartment for each contact pair (16). The mechanical linkage (52, 53, 54) for opening and closing the contacts enters each compartment through an opening in the housing. Part of the linkage is so constructed (52, 56) that this opening is shielded from the inside of the compartment. An arc chute (68) with baffles (72) and outlet screen (76) for cooling expelled gas is fitted on top of each compartment. The use of individual contact compartments, and the shielding of the mechanism openings, ensure that, when the contacts part under fault conditions, a considerably overpressure results and is maintained sufficiently long to cause an appreciable increase in arc voltage. This gives greater fault handling capability to the circuit breaker. For ease of maintainance the housing is made in sections (14, 58) so that individual contact assemblies can easily be removed for examination and repair.