SU1241129A1 - Device for measuring resistance with relative reading - Google Patents

Abstract

The invention is intended to test and certify precision resistors, measures, resistance stores, bridges. Accurate resistivity measurements with nominal values that are not multiples of 10 + K, where K is an integer, are applied at a constant current using exemplary resistivity measures using the method of substitution of ratios. The aim of the invention is to increase the accuracy and performance of measurements, achieved by eliminating the effect of instability of the resistor l. (L / 75..e | 78, ffi3.7f rqLfT: M tfo to 4i 1C CO. W “cUh g, y Uh 23

Description

The ditch and the elimination of the need to connect each resistor to a measure of the ratio and shoulders of the magazine ratio. The adjustment contains adjustable resistors 1 and 2, clamps 3-8 for connecting measurable and exemplary measures, pins 9-12, switches 13 and 22 with pins 14-21 , power source 23, 1 | Gl 25, switch 26 with contacts 27-29, 24 and

, -,

30, output connections: decades. Deck The invention relates to electrical measuring equipment and can be used to calibrate and certify precision resistors, measures, resistance boxes, bridges, and perform other accurate resistance measurements with nominal values that are not multiples of 10 (where K is an integer), on a constant current using reference and exemplary resistive measures by the relationship method.

The aim of the invention is to improve the accuracy and performance of the resistance measurement by eliminating the influence of the instability of the resistors of the ratio measure on the value of the ratio and eliminating the need to calibrate each resistor of the ratio measure and the store ratio arms.

The drawing shows a block diagram of a device for measuring resistance with a relative readout.

The device contains adjustable shoulders of ratios .1 and 2 with high-low and low-resistance decade current resistances 3 and .4 and potential 5-8 clamps for connecting measurement measures and differential measures. The clamps 5, 3, 8 and 4 of C are connected respectively with contacts 9, 10, 11 and 12 of the first two-pole switch 13 to three positions. Pole 14 of the switch 13 is connected to the contact 15 of the pole 16 and the conduit 31 consists of resistors 33-42, decade 32 - of the resistors 43-53. . Keys 54-72, switches 73, 74 with. contacts 80-83. To achieve this goal, the ratio measure is made in the form of series-connected sections of resistors of the same rating, forming Decades 31 and 32, and a three-pole bipolar switch 77 is inserted into the device. 1 Il.

17 is 18 and 15 is with contact 20 of pole 18 and contact 21 of pole 16 of a two-pole switch 22 into two positions. Pole 16 is connected to the positive, and pole 18 is connected to the negative pole of the power supply 23. The arms of the ratios 1- and 2 are connected to clips 5 and 8, respectively, and the top 24 of the center of relations 1 and 2 is connected to the first terminal of the null indicator 25, the second terminal of which is connected to the pole of the single-pole switch 26 to three positions. The contacts 27 and 29 of the switch 26 are connected to the clips 6 and 7 and the top 30 decades of the 31 and 32 ratio measures, respectively. Decades 31 consists of resistive sections 33-42, and decade 32 consists of resistive sections 43-53 having the same nominal value. Each pair of resistive sections 33-53 is provided with keys 54-72 that connect the input of one resistive section with the output of the other. The inputs of sections 33 and 43 are connected to apex 30, and the output of each section is connected to fixed contacts of decade switches 73 and 74, the pole of switch 73 is connected to pole 75, the pole of switch 74 to three positions of the second bipolar switch 77. Contacts 78 and 79 of the plate 75 are connected to clips 5 and 8, and contacts 80 and 81 of the pole 76 are connected to clips 8 and 5, respectively. The contacts 82 and 83 of the poles 75 and 76 and the contacts 84 and 85 of the poles 14 and 19 remain free.

The device works as follows.

For accurate measurements, the approximate value of the resistance of the resistor under study is known. As an exemplary (reference) measure, measures are used with a nominal value of a multiple of Ohms (where K is a whole and also transitional measures that generally produce multiples of 10-5 2.5. 0,4t10t, (where K is a whole). Based on these data, in the decades 31 and 32, the ratio measures using the switches 73 and 74. recruit such a number of resistive sections, in which the shoulders, compared with the decades formed 31 and 32, are in the same ratio as

R ,, (1 + V n iK

k ;-() th () 1.71 and

where R and 8; - nominal value

resistance from the nominal value of each resistor; n is the number of resistors. The resistance of the resistors of the ratio measures can be easily adjusted with an error of 0.003-0.01%, then, learning that R, R ... "can be written down by an error not exceeding 1-10,

Rjiil-ilU n2 (2) Rp "()

From expression (2), it follows that for parallel and series connection of resistors the ratio measures, the relative deviations of their common resistance values from the nominal values are peculiar.

Using this property, in shoulders, relations 1 and 2 establish the same relationship as between measures 31 and 32 of the ratio measures. With the help of adjustable decade levers of the shoulder. Ratio 1 balance the resulting bridge circuit and remove the relative count oi,. Using keys 54-72, the resistive sections included in each decade of the ratio measures are switched from serial to parallel and switch 77 is switched. Decades 31 and 32 of

j, y

15

29

studied and exemplary measures (or as close as possible to him). Through the switch 77, decades of decade 31 and 32 are connected to terminals 5 and 8, and the null indicator through switch 26 to the top 30. Through switches 13 and 22, the circuit is energized. The value of the supply voltage is chosen so as not to exceed the permissible amount of power dissipated on the studied and exemplary measures. If R + Sg and Rp Rp (1 + 5p) are the common resistances of the series and parallel connection of resistors of the same nominal, where RgH p are the nominal resistance values, and S s are the relative deviations from the nominal value,

(one)

one shoulder comparison to the other. Again balance the bridge circuit and remove the countdown of. The systematic errors associated with the deviation of the resistance value of the resistors by the measure of the ratio from the nominal one are included in both relative readings of and, but with a different sign, therefore, with the addition of -v and & a: are excluded.

with . The systematic errors associated with the deviation of the impedance value of the shoulders ratio from the nominal one are included in both counts, but with the same sign, therefore the value

--G - gives the desired amendment. Turning off the switch 77 of the decade 31 and 32, connect the test and exemplary measures (to terminals 5, 6 and 7, 8

two-terminal connection and to terminals 3,5, 6 and 7,8,4 with four-terminal connection). Balance the circuit and take the countdown to, The real value of the studied measure at

connecting it to the clamps 5 and 6 we obtain from the formula.

R, R, (1 p ,, - C - H (3) where R. Is the nominal value of the measured resistance; n is the relative deviation of the resistance of the reference (reference) measure from the nominal value.

When connecting the measure to the terminals 7 and 8 - from the formula

Khts (1

q (i + (Xj T

+ p - c /, + 4-) (4)

An example. Resistance is measured to a nominal value of 9000 ohms. The resistance of the resistive sections of the ratio measures is 10,000 ohms. Switch 73 includes in the decade 31 10,000 and switch 74 in the decade 32 - 90000 Ohm (all the keys are open at the same time). The zero indicator is connected to point 30, decades 31 and 32 are connected to terminals 5 and 8, the ratio is set to 1: 9 in the ratio arms, equilibration is performed and the oi count is taken. The keys 63-70 are closed, the ratio measures are taken the reading is removed (the ratio of 1: 9 is preserved). Disable the measure of relationship and connect to the terminals 7 and 8 of the investigated measure R, and to the terminals 5 and 6 - a model measure of 1000 ohms. Balance the circuit and remove the readiness of оСR 9000 (1 + п)

In order to eliminate the influence of thermo- | electromotive force balancing. produced by the method of false zero at two directions of supply current. A switch 22 serves to change the direction of the current.

The ratio measure allows to get a wide range of support relations in diapason 1 - 1/10, for example 1/2, 1/4, 1/3, ... 2/9 ... 4/7 ... 5 / 11, etc. (basic range), and a number of auxiliary relations in the range of 1/10 - 1/100, for example, 1/20, 1/30 ... 1/12 ... 1/49, etc. Considering that exemplary and reference measures in use may have multiples of 2.5-10-VO, 4-10-, 9.10 in the range of 1-1 / 10, using this device, you can get a number of relations in which one ratio differs from the neighboring one by no more than 2%, which makes it possible to measure measures with any nominal value with a standard deviation of 10 with eliminated systematic errors.

Thus, the invention makes it possible to eliminate the influence of unstable

s 0 5

0

0

five

0

These resistors measure the ratio of the value of the ratio and obtain a series of reference relations free from systematic error, eliminate the need for calibration and increase the measurement accuracy by 2.5 times in comparison with the known devices.

F, formula of invention

. A device for measuring resistance with relative readings, containing the first bridge circuit, the two arms of the ratio of which are formed by high-resistance and resistance impedance decades, the other two arms by the measure of ratio, the second bridge circuit, the two arms of which are formed by the same high resistance and low resistance of the resistance , two other arms - current and two potential clamps for connecting measured and exemplary measures, respectively, the first potential clamps of each shoulder of the second bridge center The chains are connected to the first fixed contacts, and the current terminals to the second fixed contacts of the first two-pole switch in three positions, the poles of which are connected respectively to the first fixed contacts of the two-pole switch in two positions, the second fixed contact of the first pole of the two-pole switch to two positions is connected to the second pole first two-pole-; A three-position switch, a second fixed contact of the second pole of a two-pole switch of two positions is connected to the first pole of a first two-pole switch of three positions, and the two potential terminals of each arm of the second bridge circuit are connected to the poles of a two-pole switch of two positions respectively, with the first and second fixed contacts of the single-pole three-position switch, the pole of which is connected to the first position by a zero-indicator a, the second terminal of which is connected to the top of the measuring diagonal of both bridge circuits, characterized in that, in order to increase the accuracy and performance of the measurement by eliminating the influence of instability of the resistors of the ratio measure on the value of the ratio value and eliminating the need to calibrate each ratio of the ratio measure and the ratio arms, in it a measure of the ratio is implemented in the form of series-connected sections of resistors of the same rating, forming two decades with pins from each section to contacts of the decades switches, and a second bipolar switch for three positions is inserted in the device, the first pole of the second bipolar switch is connected to the pole of the ten-decade switch of the first decade of the ratio measure, the second pole is connected to the pole of the ten-decade switch of the second decade of the ratio measure, the second fixed contact of the first pole of the second bipolar pole a three position switch is connected to a third

the fixed contact of the second pole of the second bipolar switch for three positions and the first potential terminal for connecting the measured measure of the second bridge circuit, the second fixed contact of the second pole of the second bipolar switch for three positions is connected to

the third fixed contact of the first pole of the second bipolar switch to three positions and with the first potential terminal for connecting an exemplary measure of the second bridge circuit, a key is inserted into each pair of sections of resistors of ten decades, one of the outputs of which is connected to the input of one section, and the other output from the output of the next sekhsha, while

the top of the measuring diagonal of the first bridge circuit is connected to the third fixed contact of the single-pole switch in three positions.

Claims (1)

Claim . A device for measuring resistance with a relative reading of readings, containing the first bridge circuit, the two arms of the relationship of which are formed by high-resistance and low-resistance decades of resistance, the other two shoulders are a measure of the ratio, the second bridge circuit, the two shoulders of the relationship of which are formed by the same high-resistance and low-resistance decades of resistance, two other shoulders - current and two potential clamps for connecting measured and exemplary measures, respectively, the first potential clamps of each shoulder of the second bridge circuit with connected to the first fixed contacts, and the current clamps to the second fixed contacts of the first two-pole three-position switch, the poles of which are connected respectively to the first fixed contacts of the two-pole two-position switch, the second fixed contact of the first pole of the two-pole two-position switch is connected to the second pole of the first two-pole switch to three positions, the second fixed contact of the second (pole of two-pole switch to two positions inen with the first pole of the first two-pole switch to three positions, and the terminals of the power source are connected to the poles of the two-pole switch to two positions, the second potential clamps of each arm of the second bridge circuit are connected respectively to the first and second fixed contacts of the single-pole switch to three positions, the pole of which is connected to the first output of a null indicator, the second output of which is connected to the top of the measuring diagonal of both bridge circuits, characterized in that, in order to increase accuracy and measurement performance by eliminating the influence of the instability of the resistor of the measure of the ratio on the value of the ratio and by eliminating the need for calibration of each resistor of the measure of the ratio and the shoulders of the ratio, it measures the ratio in the form of series-connected sections of resistors of the same nominal; two decades with leads from each section to the contacts of the decade switches, and a second two-pole switch to three positions is introduced into the device, with 15 the first pole of the second two switch is connected to the pole of the decade switch of the first decade of the measure of relations, the second pole is connected to the pole of the decade switch of the second of the 20th decade of the measure of relations, the second fixed contact of the first pole of the second two-pole three-position switch is connected to the third fixed contact of the second pole of the second two-pole three-way switch position and with the first potential clamp for connecting the measured measure of the second bridge circuit, the second fixed contact of the second pole of the second bipolar the three-position switch is connected to the third fixed contact of the first pole of the second two-pole three-position switch and to the first potential clamp for connecting a standard measure of the second bridge circuit, a key is inserted into each pair of decades of resistor sections, one of the terminals of which is connected to the input of one section, and the other conclusion is * with the output of the subsequent section, while the top of the measuring diagonal of the first bridge circuit is connected to the third fixed contact of the unipolar switch in three positions.