GB1135351A - Fused electric switch - Google Patents

Abstract

1,135,351. Snap-action switches; automatic circuit-breakers. WESTINGHOUSE ELECTRIC CORP. 2 Jan., 1967 [3 Jan., 1966], No. 21/67. Heading H1N. A switch 11 is mounted in an insulating casing 5 which also carries a dismountable fuse carrier 13 carrying a fuse 71 in series with the switch contacts 15, 17, means being provided to prevent removal of the fuse unit 13 while the contacts are closed. The switch comprises a pivoted dolly 41, a contact arm 27 pivotally supported upon it and an over-centre tension spring 37 between the contact arm 27 and a fixed bracket 33. The fixed contact 15 is carried on a terminal member 19 which also serves to mount the switch upon a bus-bar (not shown). A nose 139 on the dolly 41 obstructs a projection 119 on the fuse unit 13 to prevent its withdrawal. In addition, projection 119 is arranged to strike the nose 139 so as to move the switch to its open position when the fuse is inserted although the switch is normally prevented from closing while the fuse unit is missing due to a hook 117 engaging with a fixed abutment 115. When the fuse unit is inserted its projection 119 engages the abutment 115 and hook 117 cannot engage with it but if the fuse unit is not properly seated, for instance because an overrated fuse has been inserted (Fig. 10, not shown), a gap exists between 119 and 115 permitting the hook to engage between them and prevent closure of the switch. The fuse unit consists of an L- shaped insulating member 87 carrying a spring clip 77 supporting one end of the fuse and a spring blade 93 engaging the other. When the fuse unit is inserted the blade 93 biases the fuse against a terminal structure 67 while the spring clip 77 engages a resilient blade contact 57 to complete the circuit. A lamp 99 in parallel with the fuse to indicate its failure is visible in the handle 97 of the fuse unit. The switch may be provided with automatic tripping mechanism (not shown).