GB1258645A - - Google Patents

Abstract

1,258,645. Measuring temperature electrically. TSENTRALNY NAUCHNO-ISSLEDOVATELSKY I PROEKTNO-KONSTRUKTORSKY KOTLOTURBINNY INSTITUT IMENI I.I. POLZUNOVA. Aug. 11, 1969 No.40016/69. Heading G1N. In a temperature measuring apparatus in which a plurality of thermocouples 28 are connected via individual measuring bridge circuits 1-4 to a magnetic amplifier 7 the amplifier 7 is arranged to sum the thermocouple signals and temperature sensitive elements 27 are provided in each bridge circuit to compensate for variations in ambient temperature. After initially balancing bridges 1-4 and circuit 6 thermocouple signals produced by unbalance of bridges 1-4 are applied to control windings 37-40 of amplifier 7 the summed output of which is passed to phase-sensitive amplifier 8 to produce a D.C. output proportional to the sum of the thermocouple outputs. A mean valve is obtained by connecting a voltage divider between the amplifier 8 and a meter. To determine the deviation of the total or mean signal from a set point each bridge 1-4 is adjusted for the desired set-point so that either zero signals when the measured thermocouple e.m.f.'s are equal to the set point valve or signals representing the deviation from the set-point are applied to control windings 37-40. By varying the signal from circuits 5, 6 in control winding 44, opposing the signals in 37-40, the apparatus acts as an indicator of absolute sum i.e. when the signal on winding 44 is zero or an indicator of the deviation of a sum from a set-point determined by set resistor 5. The apparatus may be used as a temperature comparator by interchanging the junctions 29-30, 31-32, 33-34 or 35-36.