Patent ID: 7820933

Claim:
A puffer circuit breaker comprising: a stationary contact assembly and a moveable contact assembly; a rod connected to said moveable contact assembly for actuating said moveable contact assembly; a support movably holding said moveable contact assembly and being arranged around said rod; a puffer volume formed between a front plate of said support and a cylinder housing of said moveable contact assembly, wherein the front plate is slidably arranged in the cylinder housing; at least one overpressure valve arranged at said support for releasing an overpressure in said puffer volume, wherein said overpressure valve comprises a moveable piston and a spring, wherein said support comprises an integrated valve cavity for receiving said spring and an integrated valve inlet opening into said puffer volume and being closeable by said piston, and wherein said moveable piston has a head that extends into an end-section of said valve inlet opening along a direction of displacement to form a seal.