GB812674A - Temperature measuring device - Google Patents

Abstract

812,674. Measuring temperature. ADDISON ELECTRIC CO. Ltd. Aug. 8, 1957, No. 24983/57. Class 40 (1). The temperature of a moving metallic object is measured by means of a roller in contact with the object, a brush bearing on the roller, a lead from the brush to a meter and a return lead to the object, the brush and lead being of a material having thermoelectric properties similar to those of the roller but dissimilar from those of the object; the E.M.F. generated at the " hot junction " (roller to object) gives a measure of the temperature of the object provided that compensation is provided for the effect of ambient temperature changes on the cold junction. In Fig. 1 a moving copper wire A1 has a nickel roller B1 in contact with it, a nickel brush C1 pressing on the roller in an axial position to collect the current. The current is led away by a nickel wire D1 to a bridge composed of three nickel-wire resistors E1, F1, G1 and a thermistor H1. The return circuit is wholly of copper via the meter M1, brush N1 and roller 01. The cold junction is thus at L1 and its temperature is sensed by the thermistor, so that variations of the ambient temperature alter the potential across the bridge which opposes the thermoelectric E.M.F., giving a true measure of the temperature of the wire. The current through the meter or the potential difference between C and N1 can be used for controlling, recording or giving warning signals, with or without amplification. Thus M1 can be a recorder or a galvanometer with adjustable contacts.