Rotating arc and expansion circuit breaker

A circuit breaker with a sealed enclosure filled with a high dielectric strength gas and containing one or more poles of the circuit breaker, each pole comprising:

• a breaking chamber having a revolution surface tightly sealed at both its ends by end plates;
• a pair of arcing contacts having a contact area in a closed position and an arcing contact separation area in a separated position, at least one of these arching contacts being tubular, coaxially arranged in said breaking chamber and each passing through one of said end plates to make the breaking chamber communicate, in the separated position of the arcing contacts, with said enclosure forming an expansion chamber via gas outflow channels constituted by the tubular arcing contact;
• a magnet means supported by one of said end plates inside the breaking chamber so as to create in the arcing contact separation area a magnetic blowout field by rotation of an arc drawn between the separated arcing contacts;
• and
• a pair of main contact disposed outside the breaking chamber and arranged to open before the arcing contacts separate when a circuit breaker opening operation takes place, wherein said revolution surface and the end plate supporting the magnet means are made of metal and electrically connected to the arcing contact passing through this end plate, the other end plate being made of insulation material to provide electrical insulation in the open position of the contacts and wherein said revolution surface has an annular edge which is adjacent to the insulation end plate and is arranged as or supports the stationary main contact, the contact area of the arcing contacts being offset to the side of the metal end plate.