Patent GB-493329-A (GB)
Title: Improvements in or relating to electric circuit interrupters with arc extinguishing means
IPC: H01H33/18
Filed: 1937-05-27
Abstract: 493,329. High-tension switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO. May 27, 1937, No. 14723. Convention date, May 29, 1936. [Class 38 (v)] An arc-extinguishing unit 7 for a circuitbreaker comprises insulating plates 15, 17 enclosing a narrow arc passage 19, separable contacts 37, 39 within the passage, arc horns 65, 67 adjacent the contacts at each end of the passage for receiving the arc, means for moving the arc laterally on the arc horns within the passage, means such as oil for producing a gas within the passage when acted on by the arc, and venting means for leading the gas to the exterior of the structure, the arrangement preferably being such that the flow of gas produced by the arc flows through the arc. In the construction shown, a series of extinguishing units 7 is mounted with spacing members 33 on tie rods 31 supported from terminal members 3 connected to insulating bushings 2 in an oil tank 1, the separable contacts 37, 39 of each unit 7 being connected in series between the terminals 3 and a releasable contact member 9 at the bottom of each stack of units, the contact members 9 being adapted to be connected by a bridging member 11 which is moved into or out of engagement by a lift rod 13. The passages 19 in each unit 7 are annular in form and are formed by aligning narrow circular slots in the insulating plates 15, 17. The plates 15 are provided with recesses adjacent the sides of the slot to form oil pockets. The ends of the passage are enclosed by insulating plates 23, and plates 24, 25 of magnetic material. are mounted at each end of the unit, the insulating and magnetic plates of each unit being held together by tie rods 27 The upper magnetic plate 24 of the uppermost unit 7 is electrically connected at 61 to a contact foot 35 mounted on the terminal 3, and the upper plates 24 of succeeding units are connected by members 63 to the lower plates of the preceding units. The fixed contacts 37 of each unit are connected to the upper magnetic plates 24, and the movable contacts 39 pass through guide members 41 in the lower magnetic plates 25 and are linked to an actuating rod 47 passing through the central portions of the stacks of plates constituting the unit. The rod 47 is biassed to open circuit position by a spring 53. Each of the movable contacts 39 is connected by a flexible shunt 57 to a bracket 59 mounted on the lower magnetic plate 25. The magnetic plates 24, 25 are each formed with an annular recess 77 in which low resistance coils 78, 79 are mounted, the coils being connected between the magnetic plates and the arc horns 65, 67. The horns extend through a substantial portion of the circumference of the passage 19 and are provided with arcing tips in the neighbourhood of the contacts. The remaining portion of the passage is provided with insulating barriers. The arc formed on separating the contacts is transferred to the arc horns, and the arc current then passes through the coils 78, 79 and sets up a magnetic field which causes the arc to rotate along the passage until it is extinguished by the gas produced by vaporization of the oil in the passage. The arc horns are provided with slot like passages 81, Figs. 2 and 3, aligned with similar passages 83 extending through the end plates 23 ... 25, permitting the escape of gases to the exterior. To lessen the danger of flashover, the insulating end plates 23 are extended beyond the plates forming the main body of the stack, and if desired a cylindrical baffle of insulating-material may be provided around the magnetic end plate 24. Instead of a number of vents 81 distributed along the arc horns, each horn may be provided with a single vent, which may be located adjacent the contact or at the end of the horn remote from the contact. In a separate modification, Fig. 5 (not shown), the passage 19 is vented by radial passages arranged externally instead of by passages in the end plates. In another construction, Figs. 6 and 7 (not shown), the arc passage extends through an arc of 270‹ and communicates by radial ports with an annular venting chamber formed in the top and bottom insulating plates. Specification 454,186 is referred to.