Circuit breaker comprising an improved compression chamber

A circuit breaker comprising:

• an airtight container filled with a dielectric gas;
• a stationary frame arranged inside the container defining a volume with a main axis;
• at least a pair of arc contacts, the pair of arc contacts being separable from each other;
• an actuation rod that drives a first arc contact, of the pair of arc contacts, in a separation direction along the main axis inside the volume defined by the frame, upon a separation operation between the pair of arc contacts, wherein the actuation rod is connected to a second axial end of the first contact;
• a compression chamber in which a portion of the dielectric gas is compressed during the separation operation to blast an electric arc formed between the arc contacts during the separation operation;
• a cylinder and a piston connected with the rod, which are movable within the stationary frame along the main axis, for compressing the portion of the dielectric gas in the compression chamber upon the separation operation;
• a link mechanism connecting the piston to the rod, wherein the stationary frame comprises a cylindrical portion with which each of the piston and of the cylinder are radially in gastight contact and which bounds the compression chamber together with the piston and the cylinder, and
• wherein the cylindrical portion of the stationary frame comprises an orifice which communicates with an internal volume of the compression chamber through the piston allowing dielectric gas to fill the compression chamber during a closing operation of the circuit breaker;
• and
• wherein the piston comprises two or more radial collars forming at least one annular chamber in communication with the orifice of the cylindrical portion of the stationary frame.