SU1589081A1 - Method of graduating meters of temperature - Google Patents

Abstract

The invention relates to a measurement technique and makes it possible to increase the accuracy and reduce the labor intensity of the grading. The sensor 3 of the temperature of the calibrated meter 6 and the reference thermometer 4 are first placed in the thermostat 2. At the ice melting temperature and room temperature, the resistance value of the reference 4R thermometer is measured, the meter output code is recorded, the reference temperature values are calculated and a calibration characteristic is found . Then the sensor 3 of the temperature of the calibrated meter 6 is replaced with the electric equivalent of the sensor - an equivalent resistor 7 with a set of equal shunt resistors 8 and keys 9. In equality of the shunt resistors, they are convinced by the equality of the corresponding output code values of the meter 6. They are connected in series to the equivalent resistor 7 shunt resistors 8 and register the output code values of the meter 6 after each connection. From the set of output code values and the corresponding number of connected resistors 8, the coefficients of the straight line equation are calculated and the nonlinearity of the meter is estimated from the difference between the registered and calculated values of the output codes. 1 il.

Description

3

 S

EZ, then the sensor 3 of the temperature of the calibrated meter 6 is replaced with the electric equivalent of the sensor - an equivalent resistor 7 with a set of equal shunt resistors 8 and keys 9. The equality of the shunt resistors between them is confirmed by the equality of the corresponding values of the output code of the meter 6. They are connected in series to the equivalent resistor 7 shunt

The invention relates to a measurement technique and can be used in the calibration and calibration of temperature meters, in particular, temperature meters included in oceanographic measurement systems.

The aim of the invention is to reduce the labor intensity of calibration by reducing the number of reference temperature values when calibrating to two (0 ° C - ice pickup points and 20-25 ° C - room temperature) and increasing the accuracy of calibration by separating the nonlinearity characteristic of the meter and the lead operation. this characteristic to specific temperature values and nonlinearity estimates with a smaller error for a larger number of points.

The drawing shows a block diagram of a device for implementing the proposed method.

The device contains a comparator 1, a thermostat 2, a sensor 3 for the temperature of a calibrated meter, an exemplary thermometer 4 is resistant, and an exemplary measure of electrical resistance 5 (OMES), a graduated meter 6, an equivalent resistor 7, a shunt resistor 8, and keys 9.

Comparator 1 is an instrument for measuring resistance by comparison with a reference gauge. As such a device can be used comparator RZOOZ.

Thermostat 2 - Dewar vessel with a capacity of 1-2 liters, equipped with a device for mixing water, such as an electric motor with a spinner on the axis.

Temperature sensor 3 — for example, m: a single resistance thermometer, with a nominal resistance value of 100 Ω of the TCM-046 type.

The exemplary thermometer 4 is a platinum thermometer, for example, the PTS-10 type.

OMES 5 - measuring coil of type RZOZO.

The graduated gauge b is a measuring channel of the temperature of the hydrophysical complex, for example, MHI 4103.

resistors 8 and register the output code of the meter 6 after each connection. From the set of output code values and the corresponding number of connected resistors 8, the coefficients of the straight line equation are calculated and the nonlinearity of the meter is estimated from the difference between the registered and calculated values of the output codes. 1 il.

0

five

0

five

The equivalent resistor 7, for example, type C2-29B 1120m, is intended to simulate the resistance value of sensor 3 for temperature, corresponding to the upper limit of the measurement range.

The shunt resistors 8 are designed to reproduce several points when evaluating the non-linearity of the meter. As resistors two resistors of C2-29B 8.6 kΩ and SDR-9 1 MΩ can be used in parallel.

The keys 9 are designed to separately or simultaneously connect the shunt resistors 8 to the equivalent resistor 7. One of the key contacts is interconnected and connected to the second contact of the equivalent resistor 7, and the second contacts of the keys 9 are connected to the free terminals of the corresponding shunt resistors 8. As keys MT-1 toggle switches can be used.

The calibration method is carried out as follows.

First, the temperature sensor 3 is connected to the calibrated meter 6 and immersed in the thermostat 2. An exemplary thermometer 4 is also installed in the latter, which together with the OMES 5 is connected to the comparator 1. The thermostat 2 is filled with a water-ice mixture and the stirrer is switched on. After holding for 30 minutes, several 5 values are recorded (for example, 10) of the output codes L, - meter and comparator reading / (, -.

Then thermostat 2 is freed from the water-ice mixture, filled with water at a temperature equal to the ambient temperature (room temperature + 24 ° C), and 0 after measurements for 30 min, repeat the measurements, i.e., Nt and / WITH,-.

Calculate the average values of output codes for NT and comparator readings / Co and / C. at zero and room temperatures, respectively, according to the formulas

TO

-y-)

0

five

° (Ko ()

where t is the number of measurements.

The resistance values of the reference thermometer 4 are determined at zero temperature () and room temperature (Rr) by the formulas

Lo Co A OMES (2)

. To-oz. (3)

where is the actual resistance value of the model measure 5.

Using the obtained resistance values of the reference thermometer and at zero temperature and room temperature, as well as the coefficients given in the certificate for an exemplary thermometer, model reference values of temperature tf, t-r are calculated. From the combination of values and o, N and t, the coefficients of the calibration characteristic of the meter are calculated. kind of

/, - a + 6M (4)

by formulas

i);

a bNo - tQ

After these operations, the temperature sensor 3 is disconnected from the meter 6 and an equivalent resistor 7 is connected in its place, in parallel with which shunt resistors 8 are connected in series with keys 9, the resistances of which are equal to each other. The equality of the resistances of the shunt resistors 8 can, if necessary, be carried out directly according to the indications of the meter 6. For this, the shunt resistors 8 are alternately connected to the equivalent resistor 7 and are convinced that the meter 6 has equal readings. If the indications of the meter 6 are unequal, the resistance of the shunt resistors 8 is adjusted by changing variable resistor. At least three values of the output codes of the b meters are registered before connecting to the equivalent resistor 7 of the shunt resistors 8 and after connecting each subsequent one in parallel to each other. Taking the number of reproducible to assess the nonlinearity of points equal to n, use n-1 shunt resistors 8 and keys 9. In this case, the value of the resistance RUJ of the shunt resistors

1 1.1 -, g: t-fi.

RH Rf Rui

 (7)

and Rg are the resistance values of sensor 3 corresponding to the upper and lower limits of the range of measured temperatures, and the resistance of the equivalent resistor is chosen equal to the resistance Rf of sensor 3.

ten

From the set of values of the output codes Ni and the number of the corresponding shunt resistors corresponding to them, the coefficient of the form is determined using the least squares method

Ni No + Kn, (8)

where yVo, L, are the values of the output codes of the meter before connecting and after connecting the "i number of shunt resistors; l, is the number of connected shunt resistors.

For each i-th measurement, the difference is

A, yV, - (/ V, -) p, (9)

15 where (/ V;) p is the value calculated by the formula by substituting the found value K and n, the number of resistors.

The nonlinearity of the meter is estimated qualitatively as the distribution of the values of A, in the range of measurements and quantitatively as the maximum absolute and positive and negative values of the difference D, or the standard deviation of the entire set of values L ,.

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Claims (1)

Invention Formula The method of calibration of temperature meters, which consists in the fact that the temperature sensor of the calibrated meter and A 30 model thermometer is immersed in a water thermostat, meter readings are recorded, and the resistance of the sample thermometer is measured at the melting point of ice and at room temperature, the measured temperature values are determined by the measured resistance thermometer values35 and the corresponding coefficients are determined using appropriate indications of the meter its linear calibration characteristic, characterized in that. 0 in order to increase accuracy and reduce the complexity of the calibration, after determining the constant coefficients of the linear calibration characteristics of the meter, its temperature sensor is replaced by an equivalent resistor, to which alternately 5 connect shunt resistors with the same resistance and record the meter's NO reading before connecting the first shunt resistor and reading the Ni meter after connecting each one, based on the total 0 values of the meter readings and the corresponding number n, of the connected resistors, using the least squares method, determine the coefficient K of the equation of the form Ni No + K-ni, by which the calculated values of the readings are determined and evaluate the non-linearity of the meter by the difference between its actual readings and calculated values, with the resistance of the equivalent resistor being chosen from 1589081 7® equal to the resistance of the temperature sensor where /, / / is the value of the resistance of the sensor at the upper limit of the temperature measurement range at the lower SRI, and the resistance R shunt re-and the upper range Zistor - from the ratio of measurements, respectively; J 1 15 L - the number of reproducible points   measuring range.