GB788684A - Improvements in electrical resistors - Google Patents

Abstract

788,684. Fusible cut-outs; ohmic resistors. CLAROSTAT MFG. CO., Inc. Nov. 28, 1955 [Nov. 29, 1954], No. 34008/55. Classes 37 and 38 (1). A plug-in type wire-wound resistor comprises a flexible resistance element covered by a flexible insulating sleeve the body extending in a curve, terminals at its end are spaced in parallel relationship to each other so that they fix into sockets mounted on a supporting plate of insulating material. The resistor is arranged so that if an excessive current is passed through it, it fuses and protects the circuit to which it is connected. Figs. 2, 3 and 5 show a flexible protective resistor of this type in which a wire resistance element is wound around a core 11 enclosed within a sheath or tube 12 which are both preferably of glass fibre material. The sheath 12 terminates short of the ends of core 11 so that the wires at the ends are exposed and contact is made to the end terminals. The bore of the portion 14 permits the wire to make contact with its inner surface the portion 15 having a diameter such that the sheath also may be accommodated within it. Alternatively at the junction of the sheath portions 14 and 15 there may be a constriction 16 as shown at the bottom of Fig. 5 so that a very firm contact is made between the solid plug 13 and the resistive element 10. As shown in Fig. 2, an insulating strip 20 is mounted by a tab 21 and strips 23 of metal are secured to the insulating plate 20 and have their upper ends bent so as to form sockets into which the end terminals 13 of the flexible resistor may be inserted. The portions 18 of the sockets are preferably knurled so as to make firm engagement in the sockets. Contacts to the resistor may be made by means of metal tabs 26. The end zones of the resistance have relatively high heatdissipating characteristics so that if a large surge current passes through the resistor fusing will normally occur in the middle portion. The core material 11 and the sheath 12 are made of non-combustible material.