GB1196800A - Improvements in Electric Circuit Breaker Arc Chute with Arc Discharge Muffle Assembly. - Google Patents

Abstract

1,196,800. Arc extinguishing in switches; silencers. GENERAL ELECTRIC CO. 6 Nov., 1967 [14 Nov., 1966], No. 50253/67. Heading H1N. [Also in Division F1] A current limiting circuit breaker having an arc-chute such as that described in Specification 1,196,798 is provided with a muffle 40 for the arc gasses, the muffle comprising first a set 51 of parallel, closely spaced plates 58A lying parallel to the direction of flow to cool the gasses and having parts 58B<SP>1</SP> at an angle to the plates 58B to create turbulence and prevent reflected pressure waves occurring and secondly a set 53 of parallel closely spaced plates 60 lying across the direction of flow and provided each with a plurality of small holes, holes in adjacent plates being out of alignment. In the circuit breaker (Figs. 1, 2, not shown) the arc is driven against a wall 39 having slots 39A through which the gases escape, but the arc cannot move. The muffle is longitudinally divided by insulating barriers 49A-49C so increasing the arc path that restriking within the muffle is impossible. Adjacent plates 60 are separated by narrow spacers 62 and second, smaller set 55 of plates 60 is spaced from the first by a large spacer 54; the spacers 62, 54 are divided by cross members so as to reduce the spaces between the plates to filter out the appropriate frequencies of the sound waves. The assemblies of plates, &c. are placed, in abutment, inside a pair of insulating wrappers 67, 68 and then slid into a metal casing 42 where they are retained by bolts insulated by tubes 70. The casing 42 is provided in its remote end with openings, aligned with the openings in spacer 54, for the cooled gasses to escape. The spacers 62 may be of metal or vulcanized fibre and spacer 54 and wall 39 of glass fibre reinforced melamine. In a modification (Fig. 9, not shown) the spacer 54 is replaced by a pair of U-shaped metal members.