Patent GB-444410-A (GB)
Title: Improvements in and relating to air-break electric switch fuses
IPC: H01H31/12
Filed: 1934-10-05
Abstract: 444,410. Fusible cut-outs. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(General Electric Co., Schenectady, New York, U.S.A.) Oct. 5, 1934, No. 28582. [A Specification was laid open to inspection under Sect. 91 of the Acts, April 8, 1936.] [Class 38 (i)] [See also Group XXXVII] An air-break switch-fuse comprises a cartridge-type fuse element 46 pivotally mounted at one end on a stationary contact member 41, the mounting including a toggle connection which is releasably held by the fusible link member 47 in such a manner that on the blowing of the fuse, the toggle collapses and the element 46 swings about its pivotal mounting after an initial axial movement which separates the other end of the fuse element from a second contact member 18. The contact members 18, 41 consist of metal rods which are bent as shown, and seated in grooves in the upper and lower ends of an insulator 11 secured to a cross-arm 10 on a pole by a strap 12 and two-part clamp 13. The free ends of the rod forming the contact 18 are flared outwardly to form a guide for the contact 51 mounted at the top of the fuse element 46. Each contact rod is retained in its groove and connected in the circuit by means of a combined clamp and connector 20, the clamp consisting of two interengaging parts 21, 22 provided with transverse grooves 23, 24 to receive the rods, the parts being drawn together by a stud 31 which screws to the part 21 and has a head 32 engaging the part 22. The bared end of the conductor 34 is placed in a slot 35 in the stud 31 and secured in position by a nut 36 provided with a metal clip 37 adapted to slide in the slot 35. The fuse link 47 has a contact button 49 which rests on the top of the insulating holder 46, and is electrically connected with the cap 48 carrying the contact 51 by a spring 50. The fuse holder 46 is carried on the lower contact 41 by a support 54 and a toggle lever 55, which is pivoted to the support at 56 and pivotally supported on a bushing 44 secured to the ends of the rod 41. Lateral movement of the lever 55 is prevented by side plates 57, 58 secured to the bushing 44, and an extension of the lever 55 is secured to the fuse link 47 by a screw 59. While the fuse is intact, the switch may be opened or closed by means of a switch stick provided with a hook to engage an operating handle 52. When the fuse blows, the support for the toggle lever 55 is removed, and the lever rotates to the position shown in Fig. 5, in which projections 66 on the lever engage the side plates 57, 58. The switch does not immediately open, owing to the reaction caused by the expulsion of the arc gases from the lower end of the holder 46. Shortly after the movement of the lever 55, the fuse holder begins longitudinal movement produced by the pressure of the contact 18 on the conical contact 51. As soon as the contacts are disengaged the fuse holder falls over to the left to produce a wide separation of the contacts. The toggle lever 55 is provided with an opening 67 to permit of its removal, with the fuse holder, from the contact 41 for replacement of the fuse. The recoil action of the fuse holder tends to lift the toggle lever 55 from the sleeve 44 during the initial movement to the position shown in Fig. 5, but this is prevented by a latch 68 which is pivoted to the support 54 and guided by pins 69, 70 on the toggle lever to close the opening 67 during this stage.