A puffer type gas blast circuit breaker.

摘要

An insulation nozzle (10) for the puffer type gas blast circuit breaker moves together with a movable arcing contact (14). A downstream divergent section of the insulation nozzle (10) includes a first annular triangular groove (34) and a second annular triangular groove (36). The first triangular groove (34) is disposed downstream to a intermediate throat section (32) of the insulation nozzle (10). The second annular triangular groove (36) is disposed downstream to the first annular triangular groove (34) and so dimensioned that an angle (P2) of a line between the downstream edge (40) of the intermediate throat section (32) and downstream ridge (44) of the second annular triangular groove (36) is smaller than an angle (P1) of a line between the downstream edge (40) of the intermediate throat section (32) and the downstream ridge (42) of the first annular triangular groove (34) to the axis of the insulation nozzle (10), whereby part of compressed blast gas is directed to the visinity of the front end portion of a stationary arcing contact (12) to apply a dynamic pressure thereat until the insulation nozzle (10) leaves the stationary arcing contact (12) to thereby prevent sudden pressure drops of the compressed blast gas thereat which causes an electrical breakdown between the arcing contacts (12, 14).