GB478161A - Improvements in electrical resistance elements - Google Patents

Abstract

478,161. Variable-resistances; twopart couplings. WESTON ELECTRICAL INSTRUMENT CORPORATION. March 24, 1937, No. 8648. Convention date, April 20, 1936. [Classes 37 and 38 (i)] A resistor, particularly for temperature measurements, comprises a tubular aluminium support provided with a layer of aluminium oxide for insulating the resistance wire. In one arrangement, Fig. 1, the tubular support 14 which is grooved to carry the resistance winding 15 is secured to an insulating spool 11 located in a screwthreaded plug part 1 merging into an enclosing shell 3. The upper part of plug 1 receives a sleeve 5 for connecting the cable 7 with the resistor 15 through plug-andsocket couplings 10. The leads 151 to the resistor are connected by screws 17<1> and may incorporate a temperature constant resistance 20 wound on the spool 11 which is retained in position in the plug by a split ring 12. A manganin resistor 20 is employed when the main resistor 15 is of nickel. A vent 13 is provided for preventing oil or water from affecting the insulation of the terminal plugs 10. The resistance wire 15 may be coiled or it may be an ordinary layer, and it is surrounded by a thin sleeve 21, preferably of aluminium The winding may be looped back upon itself to position the terminals at one end of the tube. Fig. 4 shows oxide coatings 14a and 21a respectively upon the tubular aluminium support 14 and aluminium sleeve 21. In a modification, the shell 3 itself may be formed with an oxide coating and the space between it and the resistor unit filled with asbestos, plaster of Paris or with grease and petroleum jelly. Passages 22 in the plug 1 are provided for the employment of a sealing wire.