GB384766A - Improvements in electric fuse elements and fuses - Google Patents

Abstract

384,766. Fusible cut-outs. ROSS, F. A., 23, The Broadway, Tynemouth, North Shields. Nov. 11, 1931, No. 31217. [Class 38 (i).] A fusible element melting at a low temperature comprises a fusible metal and a spring embedded therein or conjoined in parallel, the spring being normally under tension or compression, and contracting or expanding upon fusion of the element, to open the circuit. The spring a, Fig. 3, is under tension and embedded in the fusible metal b, the spring being cut through at the centre and secured to end tails c by rivets e, e<1>, small discs d being inserted between the coils of the spring before the metal is run in. The end tails c are reduced in section by a number of holes, or by tongues g which may be used for attaching high temperature melting nickel wires h in parallel with the fusible element. These nickel wires h are embedded in arc-damping powder contained in a refractory tube to and, taking the current upon fusion of the low temperature metal, prevent the establishment of an arc across the spring elements. In a modification (not shown) silver wires are connected in series with the low temperature fusible element and the whole enclosed in arc-damping powder and a container provided with cavities into which the metal is precipitated upon fusion. In Fig. 5, a tapered spiral spring a is held in compression by the metal b and silver wires r are attached to the metal through the end sealing discs s and enclosed in arc-damping powder. Metal contact end tubes m are screwed into the' outer container o and into these tubes are projected the springs a upon fusion of the metal band severing of the contact with the silver wires &c. Specification 228,949, [Class 38 (i), Electric couplings &c.], is referred to in the Provisional Specification.