Vacuum circuit breaker

Abstract

Disclosed herein is a vacuum circuit breaker comprising a tank 31, a vacuum valve 46 horizontally installed in the tank and an insulating case 51 that has the vacuum valve installed therein, the insulating case 51 including two insulating frames 52 which are a first insulating frame with a roughly C-shaped cross section and a second insulating frame that is symmetrical in shape to the first insulating frame, and the two insulating frames being arranged with openings of the roughly C-shaped cross sections facing each other and a gap provided therebetween, wherein the insulating frames are provided at upper and lower edge portions of the roughly C-shaped cross sections with cut portions 53 and 54 for respectively passing therethrough a movable type conductive member 44 and a fixed type conductive member 48 and wherein the insulating frames 52 are provided with mounting ribs 55, mounting end surfaces 61 and tank mounting portions 59 which are used for mechanically and respectively fixing thereto the movable type conductive member 44, the fixed type conductive member 48 and a tank flange 31 a respectively.