GB1127946A - Improvements in or relating to electrical resistance thermometers - Google Patents

Abstract

1,127,946. Resistors; temperature sensitive resistors. ROSEMOUNT ENG. CO. Ltd. 30 March, 1967 [30 March, 1966], No. 14093/67. Headings H1K and HIS. A method of making resistance elements suirable for use in electrical resistance thermometers comprises the steps of rolling a strip of metal 10 into a coil with adjacent layers insulated from one another, and then slicing the roll (Fig. 4, not shown) in parallel planes normal to the axis of the roll to form a plurality of spirally wound resistance elements (14). Before coiling the strip which may be of platinum, wires 11 are secured transversely at the ends of the strip, e.g. by cold welding or soldering. The strip may also be folded end-toend. before coiling to present the wires 11 at the centre or on the periphery (Figs. 2, and 3, not shown).. The insulation 12 may be a strip of any suitable material or may form a coating such as silicon varnish on a surface of 'the metal. Alternatively the insulation may be alumina powder mixed with a wax. Before being sliced the roll may be encapsulated in an epoxy or alkyd resin, a ceramic or glass or a plastic e.g. polythene. :The element may have leads 15 connected) e.g. by spot-welding or soldering, and may be trimmed to approximately its final value by lapping or etching, (or in the embodiment of Fig. 3, by peeling back the outermost layer and fusing the metal strip at the fold). The disc (14) may be secured to a ceramic disc precoated with glass.