SU1362960A1 - Device for measuring temperature - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to simplify the device and increase the measurement accuracy. The device circuit includes an operational amplifier 1, a source 2 and a divider 3 of the reference voltage, fixed resistors 4-6 and a resistance thermometer 7. The introduction of new elements and the formation of new connections between the elements of the device allows one to linearize the characteristic temperature — the output voltage when using platinum resistance thermometers, the characteristic of which is approximated by a linear fractional function. 1 il. (L with O5 to with O5

Description

The invention relates to a measurement technique, namely, temperature measurement devices, and can also be used in other fields of technology to compensate for the non-linearity of transducers of measured values to resistance, having a characteristic approximated fraction by a linear function.

The aim of the invention is to simplify the device and improve the measurement accuracy.

The drawing shows a diagram of the proposed device.

The device contains an operational amplifier 1, a source 2 and voltage dividers 3, constant resistors 4-6 and a resistance thermometer 7. Source 2. The reference voltage of the first pole is connected to the common bus. The inverting input of the operational amplifier 1 is connected to the first terminals of resistors 4 and 5, the non-inverting input to the first terminals of thermistor 7 and resistor 6, the output to the second terminals of resistors 5 and 6, the second terminal of thermistor 7 is connected to the reference voltage divider 3 and the second pin of the resistor 4 -. to the second Pole of the source 2 reference voltage.

The output of the device is the voltage across the non-inverting input of op amp 1

The device allows to linearize the characteristic temperature - output voltage when using platinum resistance thermometers whose characteristic is approximated by a linear fractional function of the following form:

RTC (T) R.,) (1 +

  from 1 l

de

R, (T)

R ,, (J,)

BUT,

resistance of resistance thermometer at temperature T; the resistance of the resistance thermometer at a certain temperature T .; coefficients;

i - thermometer temperature

resistance

The device works as follows.

x b--

13629602

The voltage on the inverting (U) and non-inverting (U) inputs of the operational amplifier 1 in the absence of saturation of the latter are

and and. (2)

And there are equal

Uf-U- U - Uy

RI

R.

(3)

U2-U + R (T)

mc

R

(four)

where and is the voltage of the source 2 of the reference voltage; voltage divider 3 support voltage; the voltage at the output of the op amp; resistances of resistors 4-6, respectively. Under the conditions

and.

and.

U, and, R Ri-cCTi) -and ,, K, Kz O, (5) + (T) B + RjR (T; A-R l3B 0 (6)

where R4 is the internal resistance of the divider 3 and taking into account (1) the output voltage of the device depends on the temperature

ivyTST) -i, BT.

(7)

Formulas of the invention

A temperature measuring device containing a voltage source connected by a first pole to a common bus, an operational amplifier whose inverting input is connected to the first terminals of the first and second resistors, a non-inverting input to the first terminals of the thermistor and the third resistor, output 50 The second resistor of the first resistor, and the fourth resistor connected between the second resistor of the thermistor and the common bus, differs from the fact that, in order to simplify and improve the measurement accuracy, the device ene fifth resistor connected between the second terminal of the thermistor and the second pole of the reference voltage, which so31362960 4

The one with the second output of the second resistor is connected to the output of the opacistor, and the second output of the third real amplifier.

Compiled by V. Zhuravlev. Editor Y. Sereda Tekhred L. Serdyukova

Order 6390/28 Circulation 776. Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Proofreader. Cherni

Claims (1)

Claim A device for measuring temperature, containing a reference voltage source connected to the first bus with a common bus, an operational amplifier, the inverting input of which is connected to the first terminals of the first Where R _rc (T) is the resistance of the resistance thermometer at temperature T; R _TC (J,) ~ resistance of the resistance thermometer at a certain temperature T. ₍ A, B are the coefficients; T is the temperature of the resistance thermometer 4. The device operates as follows. and the second resistor, non-invert. the input is with the first terminals of the thermistor and the third resistor, the output is with the second terminal of the first resistor, and the fourth resistor is connected between the second terminal of the thermistor and the common bus, characterized in that, in order to simplify and improve the accuracy of measurement, the fifth a resistor connected between the second terminal of the thermistor and the second pole of the reference voltage source, which co3 1362960 4 is single with the second output of the second resistor connected to the output of the operational resistor, and the second output of the third real amplifier.