Compressed gas electrical circuit breaker

Claim 1

A compressed-gas electrical circuit breaker comprising: a switching vessel having a compression space; a stationary contact including a contact area; a movable contact movable between closed and open positions for slidably engaging said stationary contact at said contact area and for disengaging said contacts respectively; a blasting device within said vessel including a nozzle member configured as a piston and connected to said movable contact so as to be movable therewith for compressing the gas in said space when the movable contact is moved into said open position, said nozzle member being configured for directing the compressed gas at the arc drawn across said contacts as the same disengage; and a spring-loaded shield mounted on said stationary contact in surrounding relation thereto so as to be displaceable against the force of the spring between a first position whereat said sheild closely surrounds said contact area and a second position away from said contact area, said sheild being adapted to be engaged by said nozzle member so as to simultaneously seal the compression space and displace said shield against the force of the spring from said first position to said second position when the breaker is closed, said shield being further adapted to follow said nozzle member and return to said first position under the force of said spring when the breaker is opened so as to closely cover said contact area as said movable contact disengages from said stationary contact whereby said contact area is protected from the action of the arc.