RU7209U1 - DEVICE FOR VERIFICATION OF HIGH VOLTAGE MEASURING VOLTAGE TRANSFORMERS - Google Patents

Abstract

A device for checking high-voltage measuring voltage transformers, containing a high-voltage capacitive voltage divider, consisting of a measuring and two shielding equipotential circuits in the form of series-connected capacitors with two terminals on a common axis and screens to them, a switch for short-circuiting part of the capacitors, an inductive voltage divider, which connected to the output of the verified high-voltage measuring voltage transformer, a current comparator, which consists of two adjustable arms, one of which is connected to the low voltage terminal of the high voltage capacitive voltage divider, the other through an additional capacitor to the output of the inductive voltage divider, and the middle point to the grounded terminal of the high voltage voltage transformer, and a high voltage source to which the high voltage capacitive voltage divider is connected and verifiable voltage transformer, characterized in that an additional inductive voltage divider transformer is introduced into it type with a constant output voltage equal to the output voltage of the voltage transformer being verified, and an alternating output voltage in the form of one or several decades, in which the input winding of the additional inductive divider in the process of determining the conversion coefficient of the capacitive divider in the form of a series-connected output capacitor and a closable part is connected to to the specified capacitive voltage divider and to a power source whose output voltage is equal to the operating voltage of the capacitor

Description

Polven.eya model relates to electrical engineering and is intended for testing high-voltage voltage transformers at the place of their operation at operating voltage at real load in the secondary circuit of the transformer being verified.

A device is known for calibrating measuring voltage transformers, comprising a high-voltage capacitive voltage divider., Consisting of measuring and two shielding 1-1 equipotential circuits in finally connected in series capacitors with two terminals on a common axis and screens to them. a switch for short-circuiting part of the capacitors, an inductive voltage divider, which is connected to the output of the verified high-voltage measuring transformer for n-voltage, a current comparator, which consists of two arms iLLX arms, one of which is connected to the low-voltage output of the high-voltage capacitive voltage divider, the other through an additional capacitor to the output of the inductive voltage divider, and the middle point to the grounded terminal of the high voltage measuring transformer of low voltage5 and high voltage source, to which a high-voltage measuring capacitive voltage divider is connected and a verifiable transformer of low voltage 11.

The disadvantage of the prototype described in SI is as follows:

1. The determination of pZ is carried out at a voltage that differs from the voltage US, at which the balancing of the arms of the current comparator is performed. In this case, the voltage on the capacitors C2 and C3 (Fig.), Compared with the voltage 0: 2, at which the comparator shoulders were balanced, is reduced to velrina irrz. This leads to an error in the determination of rz, due to the dependence of the capacitance 02, sz on the voltage applied to them.

2. The determination of p1 and j32 when the shoulders of the current comparator are not equal, when the balance is flat, the delay is delayed: I am from voltage U2, at which the shoulders of the commuter, the current torus are balanced. At the same time, on the capacitors C1, C2, C3, the voltage compared to the voltage UE, at which the comparator shoulders were balanced, increases to the value - U2Tfi / n,

where: rn is the shoulder of the comparator, the current is 1,

p is the shoulder of the current comparator, equal to 0.1-1.0.

This leads to an error in determining p1 ir2, due to the dependence of the capacitance 01.02.03 on the voltage applied to them.

The objective of the utility model is to increase the accuracy of a device for checking high-voltage measuring voltage transformers by determining p1, p2 and p3 at operating voltages and eliminating errors caused by the dependence of the capacitance of the capacitors on the applied voltage.

juice-capacitive capacitive voltage divider, consisting of measuring and two screens of lean equipotential circuits in the form of series-connected capacitors with two outputs on a common axis and screens to them, a switch for short} .1k.eniya short-circuit part of the capacitors, inductive voltage divider; which is connected to the output of the verified high-voltage measuring voltage transformer, a current comparator, which consists of two. adjustable arms, one of which is connected to the low-voltage output of the high-voltage capacitor a different voltage divider, another through an additional capacitor to the output of the inductive voltage divider, and the midpoint to the grounded terminal of the high voltage measuring voltage transformer, and a high voltage source to which the high voltage capacitive divider n.eprezhenin is connected, and the calibrated voltage transformer, an additional inductive voltage divider trans || juristic type, with CONSTANT} output voltage equal to output} y1y, voltage of the voltage transformer being verified, and input voltage in the form of one or several decades, in which the input winding of the additional inductive divider in the process of determining the coefficient (| conversion factor of the capacitive divider in the form of a series-connected output h of the capacitor and the desired part is connected to the indicated capacitive voltage divider and to the power source the output voltage of which is equal to the operating voltage of the auxiliary divider, while the output winding of the additional inductive divider is connected to the input of the inductive voltage divider, and in the process of balancing the shoulders of the current stripper before determining the conversion coefficients of capacitive voltage dividers in the form of a series-connected high voltage arm, a closable part and an output capacitor of a capacitive divider Ш1И in the form of a series-connected high-voltage arm and a bi-directional capacitor of a capacitive divider, the input winding of an additional inductive divider connected to the output capacitor of the capacitive voltage divider and to the power source, output n the voltage of which is equal to the operating voltage on the capacitor when determining the first conversion coefficients, while the input winding of the additional inductive divider is connected to the input winding of the inductive voltage divider.

Improving the accuracy of measuring the conversion coefficients of capacitive voltage dividers., Consisting of: series-connected closable and output capacitor of a high voltage capacitive divider; from a series-connected high-voltage closable and output capacitor of a high-voltage capacitive divider; from a series-connected high-voltage part:; ti and an output capacitor of a high-voltage capacitive divider, it is due to the fact that all these measurements are performed at the same voltages. at which the comparator shoulders are balanced. This eliminates the error in determining these conversion coefficients due to the influence of the applied voltage on the capacitance of the capacitors.

In Fig. 1, a schematic diagram is shown of a device for checking high-voltage measuring voltage transformers; figure 2 schematically shows a diagram of the measurement of pZ at operating voltage; Fig. 3 shows a schematic diagram of the balancing of the shoulders of the current comparator with the inequality of its shoulders before determining p1 ir2,

The device for checking high-voltage measuring voltage transformers contains a current comparator 1, which consists of in-phase windings 2 and 3. quadrature windings 4 and 5, indicator winding 6, which serves to connect a zero voltage regulator 7, a capacitor 8 B of the common-mode winding 3 and connected in parallel with it a variable capacitor 9, resistors 10,11,12 in the circuit of quadrature windings 4 and 5, switches 13 and 14 for measuring the number of turns of the common-mode windings of the current comparator, switches 15,16,17 for measuring the number of turns of a quad urns-windings with current comparator; multi-decade conductive voltage divider 18; verifiable voltage transformer 19 with a load of 20; capacitive high-voltage measuring voltage de-rectifier 21, which consists of an output arm (capacitor) 22, a stepwise shorted part of the capacitors of the divider 23, high-voltage arm of the divider 24, switches 28.29.3L. At the same time, the capacitive measuring divider of the voltage n. 21 consists of series-connected: and nominally r.av.nsh; high voltage capacitors with very low losses and a very small z.avislost capacitance on the applied voltage.

To measure p3 in accordance with figure 2, an additional inductive voltage divider 25 is used with a constant output voltage and an alternating input voltage, for example, О ... 1000V, which is regulated using switch 26. The voltage to the circuit is supplied from power supply 27. If G22 and 023 is eight series-connected capacitors, and the current comparator shoulders were balanced at a secondary voltage, the voltage supplied to the capacitive divider 022,023 and an additional inductive voltage divider, d lzhno be 800V. In this case, the operating voltage at the capacitors is equal to the balancing stress. This leads to the exclusion of an error caused by the dependence of the capacitance of the capacitors on the applied voltage when determining the pZ.

additional inductive voltage divider b with switch 26 and power supply 27.

. The device works the trace in a weary way. According to the amplitude of the circuit, the urine is balanced using an inductive voltage divider 18 and a change in the shoulder ratio of the windings 2 and 3 of the current comparator 1. Phase balancing is performed by changing the number of turns of the windings 4 and 5 of the current comparator. 1. carried out with the help of 1 switch 15,16,1. The transformation coefficient K of the verified transformer is equal to C13:

(i-p3)

(p2.-p4) p

where: p1 is the conversion coefficient of the capacitive voltage divider, consisting of series connected. con. Capacitors C1., CS, SZ (Fig. 1); . pS is the conversion coefficient of the capacitive low-voltage divider, consisting of series-connected capacitors P15 SZ (fig. L-);

pZ - conversion coefficient, capacitive voltage divider, consisting of series-connected capacitors 02 J SZ (figure 1).

The determination of p3. According to figure 2, performed as follows; The shoulders of the current umparator are balanced at voltage from the secondary winding of the voltage transformer being verified. Then, the circuit in accordance with FIG. 2 is assembled. The circuit is supplied from a power supply 27 with a voltage equal to the voltage across the series-connected capacitors of the closable part 23 and the output capacitor 22. The circuit is balanced with the help of the inductive voltage divider 18. The reference value obtained with the help of the divider 18 will be

close to one. To obtain a rz, the countdown, go, 11 must be multiplied by the conversion factor (1/8) of the additional inductive voltage divider 25,

Thus, an increase in the accuracy of measuring pZ is ensured by providing voltage equal to or close to the voltage at the capacitors at which the current comparator arms are balanced.

It has been experimentally established that the capacitance of capacitors is FGTI type. prsh 1enenk in the circuit, the trace depends on the applied voltage in the following way: from zero to 60V the error due to the applied

voltage negative. From BOV to SOOB, the error is zero. From 200V to 500V, the error is positive. In our case, the balancing of the arms of the current comparator and the determination of pZ are performed at zero error due to the influence of the applied voltage on the capacitor capacitance. In the process of balancing the arms of the current comparator before determining pi and p2 with the inequality of the arms of the comparator, the proposed scheme works as follows 1m. A circuit is assembled in accordance with FIG. For example, the following values are set on the shoulders of the current comparator: on the left

shoulder (13) - 0 .. on the right (14) - 1.0. At an additional inductive voltage divider 25, 500V is set. On divider 18, the unit is set. A voltage equal to the operating voltage at the output capacitor 22 of the capacitive voltage divider is supplied to the circuit from the power supply 27, when determining p1 or p2. Next, the comparator arms are ball-enslaved using a capacitor at voltages of 400V and 470V, which corresponds to a voltage drop across capacitor 22 when determining p1 and p2, respectively. The balancing of the circuit is ensured by the fact that the ratio of the arms of the current comparator and the coefficient (p | conversion factor of the additional inductive voltage divider 25 is 1/5.

Improving the accuracy of measuring p1 and p2 is due to the fact that when balancing the shoulders of the comparator, a voltage equal to the operating voltage when determining p1 and p is applied to the output capacitor.

Thus, the error Dl and c, due to the incidence of the applied voltage on the capacitor capacitance, is eliminated. In this case, a voltage is applied to the capacitor 8, which differs from 100V. But it should be within those limits at which the zero error of the capacitor is ensured, due to the influence of voltage on its capacitance, that is, within -60 - 200V.

Author J // At A. I. Nefed'ev I.

Literature Nefediev D.I. Device for checking high voltage voltage transformers. The decision to grant a patent for isobpo application N 94012519/09 from 08/01/96.

Claims (1)

A device for checking high-voltage measuring voltage transformers, containing a high-voltage capacitive voltage divider, consisting of a measuring and two shielding equipotential circuits in the form of series-connected capacitors with two terminals on a common axis and screens to them, a switch for short-circuiting part of the capacitors, an inductive voltage divider, which connected to the output of the verified high-voltage measuring voltage transformer, a current comparator, which consists of two adjustable arms, one of which is connected to the low-voltage output of the high-voltage capacitive voltage divider, the other through an additional capacitor to the output of the inductive voltage divider, and the middle point to the grounded terminal of the high-voltage voltage transformer, and a high voltage source to which the high-voltage capacitive voltage divider is connected and verifiable voltage transformer, characterized in that an additional inductive voltage divider transformer is introduced into it type with a constant output voltage equal to the output voltage of the voltage transformer being verified, and an alternating output voltage in the form of one or several decades, in which the input winding of the additional inductive divider in the process of determining the conversion coefficient of the capacitive divider in the form of a series-connected output capacitor and a closable part is connected to to the specified capacitive voltage divider and to a power source whose output voltage is equal to the operating voltage of the capacitor a divider, while the output winding of the additional inductive divider is connected to the input of the inductive voltage divider, and in the process of balancing the shoulders of the current comparator before determining the conversion coefficients of the capacitive voltage dividers in the form of a series-connected high voltage arm, the closable part and the output capacitor of the capacitive divider, or in series connected by a high voltage arm and an output capacitor of a capacitive divider, the input winding of an additional inductance first divider connected to the output capacitor of the capacitive voltage divider and to the power supply, the output voltage is equal to the voltage on the capacitor in the determination of said transformation coefficients, wherein the output winding of the inductive additional divider is connected to the input winding of an inductive voltage divider.