SU1231468A1 - Direct current meter - Google Patents

Abstract

The invention relates to the field of electrical measurements, can be used to measure large direct currents. The purpose of the invention is to reduce the mass and ggarite by using the circumferential windings in the current transformer and correction unit. The device contains a DC transformer 1, made on cores 5 and 6 with measuring winding 2, correction unit 3 has cores 7 and 8, each of which has excitation windings 9 and 10, excitation generator 11, indicator 4, synchronous demodulator 12 , a DC amplifier 13, a balancing winding 14 located on the cores 7 and 8, a compensation winding 15, a DC source of mixing 16, a bias winding. The measuring winding 2 and the compensation winding 15 are made covering the cores 5 and 6 of the current transformer 1 n the core 7 and 8 of the correction unit 3. Due to the fact that the measuring winding and the compensation winding cover simultaneously the cores a (L 7 T

Description

DC transformer and correction unit, which are located close to each other, reduce the length of the winding wires. Close to

The invention relates to electrical measurements and can be used to measure large direct currents.

The purpose of the invention is to reduce the size and size by using common windings in a current transformer and a correction unit.

The drawing shows an electrical circuit of a DC meter.

The DC current meter contains a DC transformer 1 with a measuring winding 2, a correction unit 3, and an indicator 4. The transformer

DC maker is on

two cores 5 and .6. The correction unit includes two cores 7 and 8, on each of which are located the excitation windings 9 and 10, the excitation generator 11, the output of the main frequency of which is connected to the first terminals of the excitation windings 9 and 10, the second terminals of which are interconnected and with the input of the synchronous demodulator 12, the control input of which is connected to the output of the doubled frequency of the excitation generator 1, and the output to the input of the direct current amplifier 13. The output of the direct current amplifier 13 is connected to one output terminal of the transformer constant about current 1, the other output of which is connected to the common bus, and with the first output of equalizing winding 14, located on both cores 7 and 8 of correction unit 3. The second output of equalizing winding 14 is connected to the first output of compensation winding 15, the second of which through indicator 4 is connected to the common bus. The measuring winding 2 and the compensation winding 15 are filled with the connecting cores 5 and 6 of the current transformer 1 and the cores 7 and 8 of the correction unit 3. The meter also contains a DC bias source 16, the on-positioning of the cores provides magnetic shielding of the excitation windings so that they do not need a special screen, 1 il.

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five

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between the total thickness and the first output winding of the bias 17, which is made covering the cores 5, 6, 7 and 8, the second output of which is connected to the combined terminals of the compensation winding 15 and equalizing winding 14,

The direct current meter operates as follows.

A direct current transformer 1 converts the measured direct current flowing in the measuring winding 2 into a direct current flowing in the compensation winding 15. If the magnetizing forces of the above currents balance each other, the current of the compensation winding 15 measured by indicator 4, is a measure of the measured current. The source of the bias current 16 provides the flow in the winding of the bias 17 of the direct current bias. The total magnetizing current bias and the measured current retain their sign during transients in the measured current circuit, at which the measured current can change polarity for a short time, resulting in a stable operation of the meter during the above transients.

Correction block 3 increases the accuracy of compensation of magnetizable CRT, measured current, and a and the current of compensation winding 15 as follows. Excitation generator 11 applies oscillations of the fundamental frequency to excitation windings 9 and 10. If the magnetizing forces of the windings 2 and 15 are uncompensated, then due to the presence of a magnetic flux in the cores 7 and 8 in the windings of the excitation 9 and 10, double frequency oscillations, the second harmonic of the fundamental frequency, are formed. Synchronous demodulator 12 forms a constant voltage, amplitude and sign

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which depends on the magnitude of the sign of the difference between the uncompensated magnetizing forces, since the amplitude of double frequency oscillations on the excitation windings and their phase shift relative to the double frequency oscillations at the double frequency output of the excitation generator I1 depends on them. The output current of the synchronous demodulator 12 is amplified by the DC amplifier 13 and fed through equalizing winding 14 to compensation winding I5. Since the output current of the DC transformer also flows through the equalizing winding 14 and the compensation winding, the output current of the DC amplifier I3 is added to or subtracted from it, which results in a more accurate compensation of the magnetizing force of the measured current. Due to the fact that the measuring winding and the compensation winding simultaneously cover the cores of the DC transformer and the correction unit, which are close to each other, the length of the winding wires decreases, and the proximity of the cores provides magnetic shielding of the excitation windings, so that they do not need a special the screen.

Thus, the differences in the DC-current gauge ensure smartness, its mass and dimensions.

Editor A.Gulko

Compiled by A. Puchkovsky Tehred L. Oleynik Proofreader E. Sirohman

Order 2561/50 Circulation 728. Subscription

VNISHI USSR State Committee

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

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

S 15 20 25 s

five

4684

Claims (1)

Invention Formula A DC current meter containing a DC transformer with two cores and a measuring winding, the first output terminal of which is connected to a common busbar, an indicator, the first output of which is connected to a common busbar, and a correction unit that has two seri - tsetska, on each of which the excitation winding is placed, the excitation generator, the output of the main frequency of which is connected to the first leads of the excitation windings, the second leads of which are connected to each other and to the input of the synchronous demodulator, controlling Its input is connected to the doubled frequency of the excitation generator, and the DC amplifier whose input is connected to the output of the synchronous demodulator, and the output to the first output of the equalizing winding located on both cores of the correction unit, the second output of which is connected to the first winding terminal compensation, characterized in that, in order to reduce the mass and dimensions, the measurement and compensation windings are made covering the cores of the DC transformer and compensation blocks, while Ora output terminal of the transformer a DC amplifier connected to the output DC, and the second indicator vshod - to the second terminal of the compensation winding.