GB405524A - Improvements in or relating to electric circuit interrupters - Google Patents

Abstract

405,524. High-tension switches; arcrupturing in switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.-(Assignees of Baker, B. P. ; R.F.D., 1, Turtle Creek, Pennsylvania, U.S.A.) June 14, 1933, No. 16943. Convention date, June 15, 1932. [Class 38 (v).] A circuit-interrupter has an arc-extinguishing device comprising a plurality of spaced plates of conducting material positioned along the arc path and insulated from the arc by means of insulating material, and admittance means in the form of blocks or discs of high-resistance material positioned between certain or all of said plates thereby electrically interconnecting such plates to control the voltage gradient along the plates. Figs. 2, 6 show views at right-angles to one another, and Fig. 3 a plan, of a form in which a structure is associated with each of two fixed contacts 15 adapted to be interconnected by movable contacts 9 on a bridge-member, the contacts 15 being pivoted and spring- controlled, and associated with arc horns 22. Each structure comprises a series of groups, each group comprising a magnetic plate 32 sandwiched between fibre plates 27, and plates 28 of fullerboard or other fluid (e.g. oil)-absorbent material. The plates 32 are protected from the arc (Fig. 3) by an insulating lining 26, and the plates 28 have recesses 36 for retaining arc-extinguishing fluid and cutaway parts 23 for venting arc products. The plates are further provided with slots 34, 35 such that when the groups are assembled, a continuous vertical slot 35 is formed for the movable contact 9 and a continuous vertical slot 34 into which the arc is urged by the magnetic field set up in the plates 3, 2. The plates 27, 28 are formed each with a pair of apertures 29 (Fig. 3) to receive graphiteimpregnated fullerboard discs 31 which serve to interconnect the plates 32 and provide a continuous conduction path from the arc horn 22 to a metal insert 38 in the lower plate 33, which insert is connected to a contact 40 in sliding engagement with the contact 9. In the modification shown in Fig. 15, the stack is divided into groups of which A are similar to each of the groups in the previous form, whereas each group B comprises plates 27 on either side of plates 32 between which is a mica plate 25, so constituting a condenser. At the upper end of the stack is a further condenser element M, the mica plate 25 of which is provided to strengthen the insulation at that part of the stack and the plates 32 are added to complete the condenser so as to form a part of the conduction path comprised by the discs 31 and other condenser elements. Preferably the mica plates are of progressively-increasing thickness downwards, and the groups of discs 31 of progressively-decreasing diameter downwards, so as to provide the maximum admittance at the part of the stack where the voltage gradient is normally steepest.