GB888319A - Automatic circuit-closing switch for electrical systems - Google Patents

Abstract

888,319. Electrically released switches; protective cut-out arrangements. TEDESCO, J. L. Nov. 9, 1959 [Feb. 20, 1959], No. 37839/59. Class 38 (5). An automatic circuit-closing switch suitable for parallel connection across a circuit liable to interruption comprises a porcelain body 45 closed by a porcelain cap 37 having a metal eyelet 38 in which slides a metal rod 35, the upper end of eyelet 38 clamping down a terminal 40. The toes 49 of a bi-metallic strip 50 secured to the rod 35 by a nut 53, engage a shoulder 48 to space the rod end 54 from an adjustable screw contact 55 against the action of a compression spring S, the terminals 40, 56 being connected to the ends of one " letter " forming part of a neon tube display mounted on a signboard 10, Fig. 1 (not shown). The members 37, 45 clamp between them a washer 60 having three lugs, Fig. 4 (not shown), secured to insulating spacers 62<SP>1</SP> secured in turn to the corresponding lugs of a member 19, Fig. 3 (not shown), mounted on the board 10. The rod 35 is secured to an insulating rod 33 whose upper end protrudes through an aperture in the board 10 and is enclosed by a transparent cover 31 mounted adjacent to the neon tube letter. When the latter is functioning normally the switch is inoperative, but should the tube become opencircuited the voltage across terminals 40, 56 rises to line value to produce an arc between contacts 54, 55 and a subsequent heating of the strip 50, whose legs L move inwards to allow the spring S to close contacts 54, 55 thus shortcircuiting the faulty tube. After replacement, removal of the cover 31 allows the switch to be reset by withdrawal of the rod 33. The switch housing may be modified as in Fig. 6 in which upper and lower caps 76, 65 have lugs engaging channel slots in the body 46<SP>11</SP>, Figs. 7 and 8 (not shown), the cap 65 being enclosed by a metal cover whose edges fit into a groove 66 and a channel 71, and cap 76 being enclosed by a metal cover engaging a shoulder 85 and the rim of an aperture 80, and having three lugs for attachment to spacers 62<SP>1</SP>, Figs. 5 and 9 (not shown). Another upper cap and cap cover arrangement is also described, Figs. 11-13 (not shown). If desired the rods 33, 35 may comprise a single insulating unit and the current path from the eyelet 38 to the contact 55 is through the spring 5, bi-metal 50 and nut 53.