GB956240A - Electrical translating device embodying a thermal protector for an electric motor - Google Patents

Abstract

956,240. Protective cut-out systems; thermal switches. V. G. VAUGHAN. Jan. 19, 1961, No.- 2276/61. Headings H2B and H2K. A protective system for a two-winding motor includes a current-carrying thermal element in series with the windings and two heaters, each connected to the thermal element and to one of the windings and the thermal element is also in heat transfer relation with at least one winding. The heaters 92, 96 (Fig. 12), may be connected respectively in parallel and series with the motor starting and running windings 94, 98 in series with the thermal element 18. Alternatively, the heater associated with the starting winding may be in parallel part or in series therewith (Figs. 13 and 14, not shown). In Figs. 3 and 5, the thermal element 18 is mounted on a base 10 and normally completes a circuit between terminals 20, 22 and opens this circuit with snap-action when heated above a set temperature. An insulating strip 42 located in slots 44, 46 separates the elements 18 from a heater 32 located by twisted end lugs 36, 40 in holes 28, 30 in the base 10 and having terminals 34, 38. A cover 48 for the heater 32 is held by a layer of glass-silicone ahhesive tape 50 around which the second heater 52 is wound by passing its centre through an opening 26 and double winding about the assembly so as to produce a non-magnetic heater 52. In an alternative arrangement (Figs. 8 and 10), the heater is in the form of a helical ribbon 76 of high resistance material in a recessed path 74 in a cover member 72 secured to the base 10 by tape 50 and second heater 90. In a further arrangement (Figs. 16, 17), the two heaters comprise parts of the same wire 32a on opposite sides of a connector 120 welded thereto and passing through a hole 118 in the base 10 to a terminal element 20a. The connector 120 may alternatively pass through a hole 116 to be welded to the wire 32a at a different point.