Vacuum circuit breaker assembly

Claim 1

A vacuum power circuit breaker assembly comprising a vacuum interrupter bulb including a substantially cylindrical insulating envelope and a pair of end plates heremetically fixed to axial ends of said insulating envelope through respective sealing members, a stationary electrode projecting into said insulating envelope through one of said end plates, a movable electrode projecting into said insulating envelope through the other of said end plates and axially movable toward and away from the stationary electrode, said stationary and movable electrodes being substantially in line with a longitudinal axis of said insulating envelope and respectively carrying electrical contacts at their axially inner ends for providing an arcing region between the electrical contacts when said movable electrode is moved away from said stationary electrode, a radially outer arcshield element positioned radially internally of and substantially concentrically with said insulating envelope and having an axially intermediate portion overlapping said arcing region, and a pair of radially inner arc-shield elements positioned radially internally of and substantially concentrically with said radially outer arc-shield element and being axially spaced apart from the inner faces of said end plates, said inner arc-shield elements having axially inner end portions overlapping axially outer end portions of said outer arc-shield element in an axial direction of the insulating envelope and axially spaced apart from each other by a distance smaller than the axial length of said arcing region and axially extending beyond the electrical contacts on the stationary and movable electrodes, respectively, when the movable electrode is spaced apart from the stationary electrode.