Circuit breaker equipped with an extensible exhaust cover

A medium-, high-, or very high-voltage circuit breaker, comprising at least one arc-control chamber and an outer casing defining a space in which the arc-control chamber is arranged, said arc-control chamber comprising:

• a first set of electrical contacts and a second set of electrical contacts, arranged at least in such a manner as to enable closing and opening operations of the circuit breaker;
• an arc blast nozzle;
• and
• a discharge cap forming a portion of an outer wall of the arc-control chamber, the discharge cap being situated in the space and internally defining a gas-flow chamber situated at least in part downstream from the blast nozzle with which the gas-flow chamber communicates, said discharge cap being suitable for including one or more openings for discharging a gas from the gas-flow chamber towards said space;
• and
• a support that is electrically insulating and that mechanically connects the arc-control chamber to an end wall of the outer casing of the circuit breaker;
• wherein the discharge cap comprises at least one portion that is movable under an effect of a gas pressure in the gas-flow chamber, so that a volume of the discharge cap is extensible.