SU1221617A1 - Apparatus for determining resistance of zero sequence of transformer with saturated core - Google Patents

Abstract

The invention relates to the field of measurement of transformer zero sequence parameters. The purpose of the invention is to improve the accuracy of voltage measurement. The device contains two transformers 1 and 2, having the same group of connectors and connected to the same network, limiting resistor 3, ammeter 4 and phase meter 5, Voltmeter 6 is connected between the neutrals of the secondary windings of the transformer. The introduction of a transformer 2 with a graded magnet line improves the accuracy of determining the resistance of the zero sequence. 1 il. W of with ISD Od

Description

"one

The invention relates to the measurement of the zero sequence parameters of a transformer.

The purpose of the invention is to increase the accuracy of determining the zero-sequence resistance of a transformer with a saturated magnetic wire by increasing the accuracy of measuring the zero-sequence voltage by detecting this voltage between neutral neutrals. the low voltage current of two transformers, one of which operates in a symmetrical mode, and the other in an asymmetrical load mode, as well as an increase in the accuracy of measuring the phase shift between the current and the zero sequence voltage by eliminating the angular error of the voltage transformers.

The drawing shows a diagram of the proposed device.

The device contains two transformers G and 2, having the same connection group and connecting 1X to one network, with one of the terminals of the secondary winding of the second transformer 2 through the limiting resistor 3 connected in series, ammeter 4 and phase meter 5 connected to the neutral of the secondary winding of the second transformer 2, moreover, the second terminals of the phase meter 5 and the voltmeter 6 are connected between the neutrals of the secondary windings of the first and second transformers: tori 1 and 2, a pair of free like terminals of the secondary winding of which are connected to each other with a friend.

The device works as follows.

The primary windings of transformers 1 and 2 are connected to the same network. The first transformer 1 is at idle. Phase

(this

can be any phase) of the second transformer 2, in which the zero sequence parameters are loaded on the limiting resistor 3. The magnitude of the current I of the single-phase load is determined by the indication of the ammeter 4. In this case, the magnitude of the current 1d of the zero sequence is 1 - G / 3When asymmetric the load (single phase, as in this case) the phase voltage distortion occurs, the cause of which is the zero sequence voltage trans0

161

5 5 0

0 5

0

7.2

formatter. If one or several identical phases of an asymmetrically loaded second transformer 2 and the first transformer 1 working at idle are connected, then a voltmeter 6 connected between the neutrals of their secondary windings will show a zero-sequence voltage. The magnitude of the zero sequence voltage can also be measured between the remaining transformer phases of the same name.

It is also possible to connect two pairs of like phases, but the loaded phase of the transformer should not be connected. Otherwise, the two transformers are loaded on a single-phase load, which leads to large errors. When connecting two pairs of like phases, an electrical circuit appears along which equalizing currents may flow as a result of not identical versions of transformers. If one pair of like phases is connected, Different transformers with the same winding connection group can be used. Therefore, the best option is if one pair of the same phase is connected.

The phase shift between the current and the zero sequence voltage is measured with a phase meter 5.

Knowing these values, you can determine the parameters of the zero sequence of the transformer by the formulas:

impedance (Z)

Vo

(one)

where Vj, is the zero sequence voltage;

d - current zero sequence,

active component (g) g "Z, cosCh,, (2)

where f is the angle between the current and the zero sequence voltage,

inductive component (x) ho 2 "siny, (3)

Ula Invention Form

Device for determining the zero-sequence resistance of a transformer with a saturated magneto3 12216174

wire containing a voltmeter, pu-shchennuyu magnetic conductor, while

hence the combined bound-pair of free conclusions of the same name

positive resistor, ammeter and pha: secondary windings of the first and second

A meter connected between one of the transformers is connected between the combination of output and the secondary of a secondary ob-5 bo, and between the neutrals of their secondary transformer, distinguishing windings are included a voltmeter and

Right with the fact that, in order to increase the second inputs of the phase meter, and the primary

accuracy of measurement, in both windings of both transformers the second transformer is connected with satined to the same network. ..

Claims (1)

Claim A device for determining the zero sequence resistance of a transformer with a saturated magnetic 3 wire, containing a voltmeter, a limiting resistor, an ammeter and a phase meter connected in series between one of the output and the neutral of the secondary winding of the transformer, characterized in that, in order to increase the measurement accuracy, a second a transformer with a saturated magnetic circuit, with a pair of the same terminals of the same name. The secondary windings of the first and second transformers are connected between more, and between the neutrals of their secondary windings a voltmeter and the second inputs of the phase meter are connected, and the primary windings of both transformers are dragged to the same network.