Patent GB-759461-A (GB)
Title: Improvements in or relating to multi-break electric circuit interrupters
IPC: H01H33/02
Filed: 1954-12-15
Abstract: 759,461. Fluid switches; contact members for switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Dec. 15, 1954 [Dec. 30, 1953], No. 36298/54. Class 38(5) A fluid blast switch comprises an elongated casing 21, Fig. 4, a plurality of stationary bridging contacts 43 spaced axially in the casing and a moving contact assembly 24 including a plurality of axially spaced contact rods 31, one end of each of the bridging contacts co-operating with one of the rods to make or break the circuit through the switch and the other end of each of the bridging contacts bearing against the side of another of the rods. The moving contact assembly, Fig. 8 is a ladder like structure having insulating operating rods 25 bridged by members 32 carrying the rods 31. The bridging contacts 43 are formed into two ladder like structures 42, Fig. 11, disposed at the sides of the assembly 24, Fig. 7. Each structure comprises a pair of insulating bars 44 carrying spaced support brackets 45. Each bracket 45 supports a bridging contact member 46 which is slotted at its upper end (see Fig. 11), each segment formed being biased by a spring 42 (Figs. 4 and 7), into engagement with a rod 31 and the lower end of the member 46 being biased by a single spring 56. The uppermost rod 31 makes and breaks contact with fixed contact fingers 65 connected to contact fingers 64 engaging a fixed terminal member 70, the fingers 64, 65 being biased apart by springs 66. A contact 40, Fig. 8, of the moving contact assembly co-operates with a contact carried on the conducting cross-bar of the switch (not shown). On downward movement of the cross-bar a spring 84 forces the assembly 24 down to open the contacts, arc-extinction being effected by the pressure generated at each break or by the pressure generated at some of the breaks acting on the other breaks, Fig. 31 (not shown). In either case the extinction is assisted by the blast produced by the downward movement of a piston 76 under the bias of springs 85 when the arcproduced pressure in the casing is below a desired level. Arc control devices 95, Fig. 4 and Figs. 16 to 29 (not shown), may be provided for each of some or all of the breaks and are secured against lateral displacement by insulating plates 114 secured to the casing by the insulating bolts 50 which secure the brackets 45. Shunt resistors 116 may be provided and the contacts 46 may be silver plated and have silver tungsten arc-resisting surfaces. The moving contact assembly 24 intact may be downwardly removed from the switch after removal of the devices 95. To enable the removal to be easily effected, the bolts 50 may be removed and replaced by screws which retract the contacts 46 from the rods 31, Fig. 30 (not shown). The fixed contact structures 42 may also be removed downwards after removal of the bolts 50. In a modified arrangement, Fig. 33, each pair of bridging contact members 144, 147 is housed in a metallic tube 138 supported in the casing by bolts 153 and sleeves 151. In this case the cross-member 32 moves in slots in the tube 138 and the bridging contact members and the moving contact assembly may be removed together from the casing.