Patent EA-000195-B1 (EA)
Title: Breaking device for a high rating electrical circuit breaker
Inventor: AMBLARD JEAN-YVES
IPC: H01H9/34
Filed: 1997-07-04
Abstract: 1. A breaking device for a high rating electrical circuit breaker with a molded case comprising: -a single-pole breaking cartridge (20) formed by a box with two shells (20A, 20B) made of molded plastic material, housed in the circuit breaker case, - a stationary contact (18) cooperating with a movable contact (17) to draw an arc inside the cartridge (20) when the circuit breaker opens following a fault, - and an extinguishing chamber (22) housed inside the cartridge (20) and framed by a pair of arc guiding horns (28, 30), characterized in that the two shells (20A, 20B) of the cartridge (20) are adjoined to one another to confine an internal space (32) subdivided into a plurality of compartments (34, 36, 38) arranged at different levels (A, B, C) to achieve a progressive increase of the sections for passage of the arc in the direction of the extinguishing chamber (22), the first compartment (34) near to the contacts (17, 18) being arranged at the first level (A), and causing a lamination effect of the arc drawn at the beginning of the opening travel of the movable contact (17) to foster switching of the arc onto the guiding horns (28, 30) extending into the second compartment (36), which is situated at a second level (B) and presents a width (L2) greater than that (L1) of the first compartment (34). 2. The breaking device according to Claim 1, characterized in that the terminal faces (35, 37) of the shells (20A, 20B) bounding the first compartment (34) each comprise an extension (40A, 40B) situated at the first level (A) and protruding into the second compartment (36) so as to form a chicane extending transversely between the guiding horns (28, 30). 3. The breaking device according to Claim 1 or 2, characterized in that the arc extinguishing chamber (22) is disposed in the third compartment (38) having a width (L3) greater than that (L2) of the second compartment (36), and that a first series of decompression holes (44) is arranged in each shell (20A, 20B) near to the notch (46) separating the second compartment (36) and the third compartment (38). 4. The breaking device according to Claim 3, characterized in that the notch (46) of each shell (20A, 20B) is equipped with a bevelled surface (48) to constitute a divergent before the first series of holes (44). 5. The breaking device according to Claim 1 or 3, characterized in that the third compartment (38) comprises an orifice (54) for outlet of the gases to the volume housing the mechanism. 6. The breaking device according to Claim 5, characterized in that the outlet orifice (54) is situated at the upper part of the extinguishing chamber (22), and near to the end of the upper arcing horn (28). 7. The breaking device according to Claim 5, characterized in that the third compartment (38) is provided with a second series of holes (50) communicating with an outlet channel (51) provided at the rear of the extinguishing chamber (22) and in connection with said outlet orifice (54). 8. The breaking device according to Claim 1, characterized in that the stationary contact (18) is supported by a conductor (24) in the form of a loop extended by the upper arcing horn (28), and that one of the shells (20A) is equipped with an insulating shield (56) designed to cover the portion of the conductor (24) located facing the movable contact arm (12) and extending up to the vicinity of the stationary contact (18). 9. The breaking device according to Claim 2, characterized in that each extension (40A, 40B) comprises on the outside of the corresponding shell (20A, 20B), a groove (42A, 42B) in which a ferromagnetic element, notably an electromagnetic actuator associated to the movable contact arm (12), can be inserted. 10. The breaking device according to Claim 2, characterized in that the cheeks made of ferromagnetic material can be positioned outside the cartridge (20) on the terminal faces (35, 37) of the shells (20A, 20B).