Electrical switchgear apparatus comprising an arc extinguishing chamber equipped with deionizing fins

An electrical switchgear apparatus, comprising:

• a case defining a longitudinal geometric reference plane and containing:
• an opening volume having an aperture ;
• and
• an arc extinguishing chamber communicating through the aperture with the opening volume and bounded by two opposite side walls parallel to the longitudinal geometric reference plane, a rear wall located opposite the aperture, a bottom wall and a top wall;
• a pair of separable contacts located in the opening volume and comprising a first movable contact movable along a flat path in the longitudinal geometric reference plane between a contact position and a separated position, and a second contact;
• a plurality of cooling fins located inside the arc extinguishing chamber and oriented perpendicular to the longitudinal geometric reference plane, each fin having a free edge for exposure to an arc;
• a bottom longitudinal electrode in electrical connection with the second contact, the bottom electrode at least partially covering the bottom wall of the arc extinguishing chamber;
• wherein:
• the free edges of the plurality of cooling fins collectively define a stack chamber extending in a direction from the bottom electrode to the top wall, the free edges defining the cross sectional shape of the stack chamber wherein the free edges of each fin include:
• a first tapered longitudinal portion communicating through the aperture with the opening volume,
• a second broadened longitudinal portion adjacent the rear wall, the second longitudinal portion having an oblong cross-section in a plane of cross-section parallel to the fins,
• a narrow intermediate portion joining the first longitudinal portion to the second longitudinal portion,
• wherein the stack chamber is also defined by the bottom electrode and the top wall.