TANK-SHAPED VACUUM CIRCUIT-BREAKER

PROBLEM TO BE SOLVED: To provide a tank-shaped vacuum circuit-breaker capable of improving cooling characteristics of vacuum interrupter both end portions in a ground tank, and increasing energizing capacity.SOLUTION: A vacuum circuit-breaker includes: a vacuum interrupter 2; a moving side conductor 23 and a fixed side conductor 24; a moving side contact case 9 and a fixed side contact case 13; a moving side bushing terminal 25 and a fixed side bushing terminal 26; an insulation supporting cylinder 11 and an insulation supporting body 14; and a moving side supporting plate 28 and a fixed side supporting plate 29, in a ground tank 1. The moving side conductor 23 and the moving side contact case 9 are formed so as to be hollow and communicated with each other. The moving side bushing terminal 25 and the moving side supporting plate 28 are provided with ventilation ports 25a and 28a to the outside of the ground tank 1. A ventilation passage, which communicates from the ventilation port 28a of the moving side supporting plate to the atmosphere through the inside of the insulation supporting cylinder 11, the inside of the moving side contact case 9; the inside of the moving side conductor 23, and the ventilation port 25a of the moving side bushing terminal, is formed.