SU1261419A1 - Apparatus for measuring temperature of conducting surfaces - Google Patents

Description

(46) 09/15/88, Bull. No. 34 ..

(21) 37382019 / 24-20

(22) .84

(72) V.M. Zaulin, A.A.Isaev, A.M.Lipatov, V.V.Sokolov and G.M.Imu Evich

(53) 536.532 (088.0)

(56) USSR Copyright Certificate And 714174, cl. C01 K 7/04, 1978. USSR Copyright Certificate 9 934788, cl. G01 K 7/04, 1979.

(54) (57) A DEVICE FOR MEASURING THE TEMPERATURE OF CURRENT CONDUCTING SURFACES, which contains a three-terminal thermoelectric converter, is connected with the surface, the middle electrode of which is connected through a measuring device with a variable resistor motor, in the other two electrodes of the converter connected to the output terminal; a two-electrode thermoelectric transducer with insulated junction mounted on a conductive surface, characterized in that, in order to increase the accuracy of measurement and reduce the time taken to measure the temperature, two comparators, an OR circuit, an electromagnetic relay with normally open contacts, a push button, are entered into it ., reversive electric motor with a reducer and a differential amplifier, whose inputs are respectively through a two-electrode thermoelectric converter and a contact button, in parallel with which the relay contacts are connected, are connected to the leads of the measuring device, and the amplifier output is connected to the input of the electric motor and the comparators, the outputs of which are connected via the OR circuit to the winding of the electromagnetic relay mechanically connected to the variable resistor motor. "1 The invention relates to contact thermometry and can be used in various parts of the national economy to measure the temperature of conductive surfaces using a three-electrode thermoelectric converter TP. The aim of the invention is to improve the measurement accuracy by reducing the influence on the measurement result of the step voltage and the reduction of the time spent on temperature measurement by automating the measurement process. The drawing shows a schematic diagram of the device. A device for measuring the temperature of conductive surfaces I includes a three-electrode TP 2 extreme homogeneous electrodes of which are connected to the end terminals of variable resistor 3, and the middle electrode through measuring device 4 is connected to the middle terminal of the same resistor. The balancing voltage node consists of a two-electrode TP 5 with insulated junction installed on a conductive surface, a differential voltage amplifier 6 connected to the inputs of comparators 7.1 and 7.2 with an adjustable response threshold, one of which is inverting, output No. 1 of which through the logic element OR, 8 is connected to an electromagnetic relay 9, blocking its contact 10 with the contact Start button P, and the roar of the active motor 12. The device uses a DC collector motor a, which is controlled by an amplifier 6 with a large gain factor (K 200000), which allows. at a minimum admissible unbalance input voltage uU ± 7 µV, the output voltage is sufficient to control the electric motor 12 operating in the voltage interval 0.7-4.5 V, thanks to the gearbox 13 with a large reduction factor the load on the motor shaft to negrech Comparators 7.1, 7.2 can be made on the basis of operating amplifiers according to standard schemes. The thresholds for triggering comparators are set symmetrically with respect to the zero input signal, depending on the required balancing accuracy. (In this case, they are equal to ± 1, 4 V). The device works in a dim way. A stationary isothermal thermal regime is created on the conductive surface I. By briefly pressing the Start 1I button, the circuit is switched to the balancing mode, the unbalance signal of the three-electrode 2 and two-electrode 5 TP is fed to the differential amplifier of the voltage 6, and from the output amplifier to the comparators 7.1 and 7.2. If the voltage at the input of the amplifier is less than the permissible unbalance voltage, the voltage at the output of the comparators is zero, the winding of relay 9 is de-energized and pressing the button 11 does not change the position of the contact 10 and the variable resistor 3. If exceeds the allowable voltage unbalance, then after pressing the Start 11 button, this voltage will go to the input of amplifier 6, from the output the inputs of the comparators will trigger one of them, then from the output of the comparator through the OR circuit to the electric winding agnitnogo relay which, triggered, its contact 10 will lock button P. Simultaneously with the output signal of amplifier 6 is supplied to the actuating motor 12 which, via a gear 13, rotating the axis of the variable resistor, balancing the bridge circuit. At a certain position of the axis of the variable resistor, the voltage at the input of the differential amplifier becomes equal to zero, and hence at the output associated with the inputs of the comparators and the OR circuit. The relay will de-energize, the contact will open, which corresponds to a balanced bridge circuit. At the same time, the input of the amplifier 6 is disconnected from the balanced TP and will remain disconnected until the button 1 is pressed.

Tf

eleven

 t

l

i 2 Z