GB742968A - Electric fuse-elements with reduced cross-section at one or more points - Google Patents

Abstract

742,968. Electric cut-outs. LICENTIA PATENT VERWALTUNGS GES. Oct. 7, 1953 [Oct. 11, 1952], No. 27544/53. Class 38 (1). In order to ensure the melting of a fuse element at a certain point, an incision 14 of small width is made and a solder deposit 18 applied on the part 15 of the element left by the incision, the solder forming an eutectic alloy of low-melting point with the metal of the fuse element when heated. The corners 16, 17 are bent back (Fig. 4) to prevent the formation of a current path across the incision, and they may be cut off. The incision may alternatively be a single cut (Fig. 3, not shown), or several cuts made from alternately opposite edges and each having a solder deposit (Fig. 6, not shown), or the incision may be oblique to the longitudinal axis. In another embodiment (Fig. 9) a trough 21 is formed in the element so that only the required quantity of solder is used. Arcquenching means are provided by a coating 22 of melamine, a urea resin, or other relatively carbon-free material. A particularly slow-acting element is shown in Fig. 11 where the melting point is protected against quick heat-loss by folds of the element. The eutectic alloy at the melting point may be formed before the element is used, either by direct heat or by passing a current through it.