Rotary arc type circuit breaker

A gas-blast circuit interrupter comprising:

• a gastight enclosure containing an arc extinguishing gas,
• a pair of contact members axially separable to draw an arc between the end portions of said contact members, one of said contact members being tubular and movable,
• a partition wall dividing the enclosure into two chambers of constant volume, an arc extinguishing chamber and an expansion chamber,
• an opening provided in the partition wall for the gas tight passage of the tubular movable contact,
• a gas aspiration device having a piston and a cylinder cooperating so as to produce a flow of gas through said tubular contact and a blast of gas directed towards said arc,
• an opening provided in the tubular movable contact for establishing a communication between the interior of the tubular contact and said gas aspiration device during an initial phase of the opening movement of the contacts and a communication between the interior of the tubular contact and the expansion chamber during the further phase of the opening movement thereby permitting a flow of blast gas through the tubular contact towards the gas aspiration device during said initial phase and towards the gas expansion chamber after said initial phase.