SU1689865A1 - Device for reproduction and measurement of direct electric currents - Google Patents

Abstract

The invention relates to a measurement technique and can be used to reproduce and measure a constant 18 o current in high precision measuring instruments. The purpose of the invention is to increase the accuracy of reproduction and measurement of direct currents, as well as to increase the productivity and convenience of calibration work. A device that implements the compensation principle contains a two-position. Native mode switch 1, Comparison unit 2, Slope adjustment unit 3, Sawtooth generator 4, Bias source 5, Differential capacitors Block 14, Input terminals 18, 19, Two-threshold voltage comparator 6, Time meter 7, Distribution block 8, computing unit 9 and the printing unit 10. 2 Il. 1 Outer (8x) 19 0 cl

Description

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The invention relates to a measurement technique and can be used to measure and reproduce direct current in high precision measuring instruments designed to operate in a wide range of values.

The purpose of the invention is to increase the accuracy of measurement and reproduction of direct currents, as well as increase the speed of the device.

FIG. 1 shows a block diagram of the device; Fig. 2 shows graphs of the time dependence of the output voltage of the sawtooth voltage generator (FPG), bias source (NS), their total voltage (Umn + UCM), voltages at the output of the comparator (, 11к2), measure voltage (Um) and output (compensating) current (1V).

The device (Fig. 1) contains a switch 1 of operation modes, a comparison unit 2, a slope adjustment unit 3, a sawtooth generator 4, a bias source 5, a two-threshold voltage comparator 6, a time meter 7, a distribution unit 8, a computing unit 9, printing block 10, connected in series; 11 range switch, multi-valued voltage measure 12, capacitance meter 13, 14 differentiating capacitors, two-position switch terminals 15-17, output (input) terminals 18 and 19 of the device, while one of the input (output) terminals of the device is connected directly to one from the terminals of the operation mode switch 1 and with the common wire, and the second terminal with the other terminal of the operation mode switch 1 and through the block 14 of differentiating capacitors with the output of the bias source 5; block 14 of differentiating capacitors is connected in a three-terminal scheme to the input of the capacitance meter 13, the output of which is connected to the common wire and to one of the inputs of the distribution block 8; the input of the 11 range switch is connected to the common wire and to one of the outputs of the distribution block 8, and one of its outputs is connected to one of the generator 4 sawtooth voltage inputs and to one of the inputs of the block 14 of differentiating capacitors, the other output to the multi-valued measure 12 voltage wives; the output of the multi-valued voltage measure 12 is connected to the offending wire and connected to one of the inputs of the comparator B; one of the outputs of the switchgear is connected to the common wire, to the bias source 5 and to the generator 4

sawtooth; the input of the comparison unit 2 through the switch 1, depending on the operation mode, is connected to one of the input (output) terminals of the device. With

This measurement mode is implemented with the contacts 15 and 17 of the switch 1 closed.

The device works as follows.

The device can operate in two modes - playback and measurement of direct currents. The device implements a compensation measurement method, so the measurement mode includes a current playback mode. Device operation

in this mode can be divided into two stages. The first stage — the step of choosing the steepness of the output voltage of the generator 4 — begins when the generator 4 is turned on. In this case, the known

compensating current, formed at the output of a block of differentiating capacitors 14 g, measured by current ix by comparing them. The balancing is performed automatically due to the presence of a difference error signal AU at the output of the comparison unit 2. The uncompensated current AI will cause an additional charge of the differentiating capacitor (of the corresponding sign).

This charge forms a voltage Li on the capacitor plate, to which the unit 2 of the comparison reacts. Then, from the output of the comparator unit 2, the amplified signal is fed to the regulator 3 for adjusting the steepness of the output voltage of the generator 4. At the same time (Fig.2), the slope of the output voltage of the generator 4 will automatically change until the compensation current k is equal to unknown measured current

0 ix, after which the second stage of the device operation begins - the stage of measurement of the reproduced compensating current. Thus, the second stage begins at a time ti when the steepness of the voltage rise on one of the plates of the differentiating capacitor supplied from the sawtooth generator 4 is equal to the steepness of the rise of the compensating voltage on the other plate from the unknown current ix. Further, a measurement of the reproduced compensating current is automatically performed. At time ti, when the preset voltage of the bias source 5 is compensated, the output voltage of the sawtooth voltage generator 4 (Fig. 2) will trigger a comparator 6, which will start the time meter 7. After a period of time At-- i2-t, total

the voltage Urrm + UcM will reach the level of voltage of measure 12, after which the second threshold comparator 6 will operate a second time and stop the time meter 7. The time value At will be stored in the memory of the computing unit 9, which, according to UM

Formula 1K

will determine the value

Claims (1)

compensating current. In this case, the value of the multi-valued measure 12 of the voltage UM and the value of the differentiating capacitor measured by the capacitance meter 13 depending on the position of the range switch 11 are stored in the memory of the computing unit 9 previously. Then, at the command of the computing unit 9, the level of the bias source 5 is changed (Fig. 2) and the measurement cycle of the compensating current IK is repeated as desired by the operator n number of times. The multiple measurement values of the compensating (reproducible) current are processed by the computing unit 9 and recorded by the printing unit 10 as a protocol. Apparatus of the Invention A device for reproducing and measuring DC electric currents, comprising a two-position mode switch, the output of which is connected to the input of the comparator unit, the output of which is connected to the first input of the sawtooth generator through the slope adjustment unit; bus device, the second - with the input terminal of the two-position mode selector and with the first output of the block of differentiating capacitors, to the second input of which The output of the bias source is connected, the input of which is connected to the output of the sawtooth generator, characterized in that, in order to increase the accuracy of measurement and reproduction of direct currents, as well as increase 1 speed of the device, a two-threshold voltage comparator is introduced into it, a time meter, distribution, computational and printing blocks, range switch, multi-valued voltage measure and capacitance meter, the input of which is connected to the second output of a block of differentiating capacitors, output One capacitance meter is connected to the first input of a distribution block, the output of a multi-valued voltage measure is connected to the first input of a two-threshold voltage comparator, the second input of which is connected to the output of the bias source, the first output of the range switch is connected to the second input of the distribution unit, the second output of the range switch is connected to the input of a multi-value voltage measure, the third output of the range switch is connected to the third input of the sawtooth generator and the first input of the differentiating capacitors, the third input of the distribution unit is connected to the second output of the bias source and the second input of the sawtooth generator, the output of the distribution unit is connected to the input of the computing unit, the output of which is connected to the input of the printing unit, the input of the time meter is connected to the output of the comparator, and the output of the time meter is connected to the input of the distribution unit. UCM UrtJH + UCM 0 0 % 0 Uvk 0 -Twoh t Mq  t