SU1541543A1 - Device for testing switches for disconnection of capacitive current - Google Patents

Abstract

This invention relates to the field of electrical engineering. The purpose of the invention is to increase the reliability of the test results and to expand the scope of application by enabling the operation of the shutdown mode of power filters and filter compensating devices. Due to the introduction of the second capacitor 6 and the connection between the first capacitor 1 and the secondary winding of the first transformer 3 of the switching element 2, and also by turning on the reactor 8 parallel to the primary winding of the first transformer 3, and the series circuit from the test switch 5 and the second capacitor 6 - parallel to the secondary The winding of the second capacitor 7 ensures the equivalence of the operating conditions of the switch 5 in the test circuit and in the real network. 1 hp f-ly, 2 ill.

Description

1

The invention relates to electrical engineering, in particular to the field of testing high-voltage circuit breakers in the mode of disconnecting a capacitive load.

The aim of the invention is to increase the reliability of the test results and to expand the field of application by enabling the operation of the shut-off mode of power filters and filter-compensating devices.

FIG. 1 is a schematic of a device for testing circuit breakers in the unloaded line or single capacitor bank shutdown mode in FIG. 2 is a diagram of the device in the off mode of the power filters and filter compensating devices,

The device (Fig. 1) contains serially connected first capacitor 1, including element 2, first transformer 3, auxiliary switch 4, test switch 5 and second capacitor 6, and also the second transformer 7, the secondary winding of which is connected in parallel to the tested switch 5 and the second capacitor 6. Parallel to the primary windings of transformers

3 and 7 are connected respectively to the reactor 8 and the voltage source 9, usually supplied with a voltage regulator. The capacitance of the second capacitor 6 is less than the capacitance of the first capacitor 1, and the inductance value of the reactor 8 is selected from the condition of tuning to the industrial frequency of the switched-off current circuit.

When testing switches in the power off mode or filter compensating circuits to reproduce the highest harmonic in the switchable current (Fig. 2), the primary winding of the transformer 3 is connected to the reactor 8 via the third capacitor 10, and between the test switch 5 and the second capacitor 6 The transition voltage recovery circuit is connected, for example, from the reactor 11, in series with which the series-connected resistor 12 and the fourth capacitor 13 are connected.

The device works as follows.

In the initial state, the switches

4 and 5 are closed, and the switching on element 2f, for example, the trigatron, is open. The first capacitor 1 is charged by

with

jg

| 5

0 5

about ,,

about 45

five

of a direct current (not shown) to a value determined by the ratio of capacitors 1 and 6. If the attenuation in the circuit is not taken into account, at a ratio of capacitances equal to, for example, 10, the capacitor 1 must be charged to 0.55 of the normalized constant value component of the restoring voltage. After switching on the oscillatory circuit, the switching-on element 2, which is produced near the maximum of the EMF of the transformer 7, switches off the charging current of the second capacitor 6 through switches 4 and 5. Since the natural frequency of the current is equal to the industrial frequency, the half-cycle of the current of the industrial frequency flows through the switches its zero across the voltage across the capacitor 6, with the capacitance ratio being assumed and without attenuation, is 1.818 times the voltage of the capacitor 1, i.e. equal to the normalized constant voltage component of the restoring voltage. After a break of current by switches 4 and 5, the voltage on the high voltage winding of the second transformer 7 has an amplitude value that coincides in magnitude and polarity with the voltage on the capacitor 6. As a result, a constant voltage of the capacitor 6 acts on one pin of the test capacitor 6, and on the other, the alternating voltage of the second transformer 7, i.e. real conditions of voltage recovery on the switch in the mode of switching off the capacitive load are reproduced. This ensures the equivalence of the operating conditions of the circuit breaker in the test circuit and the real network, therefore, the reliability of the test results increases.

Connecting the reactor 8 and the third capacitor 10 parallel to the primary winding of the first transformer 3 (Fig. 2) forms a circuit, the transient process in which, after switching on element 2, provides the highest harmonic in the switchable current, the frequency of which is determined by the capacitance value of the third capacitor 10. The voltage drop on the inductance reactor 11 increases the voltage on the second capacitor 6 in accordance with the actual conditions of the fiber operation, and the arc breaks down with the test switch

51

5, the increased voltage of the second capacitor 6 is applied to the filter lead of the switch 5, and this voltage is superimposed by high-frequency damped oscillations of the circuit formed by the reactor 11, the fourth capacitor 13 and the resistor 12, i.e. With appropriate selection of parameters, this circuit provides a real transitional regenerative voltage on the filter side in the off mode of the power filters and filter compensating devices.

Thus, the introduction of additional elements into the circuit (the second and third capacitors, the switching element and the restoring voltage shaping circuit), as well as the change in the connections between the elements providing the charge of the disconnected capacitor to almost double the voltage of the first capacitor. the voltage across the test switch, i.e. to increase the reliability of the results of its testing, as well as to expand the scope of application of the circuit, providing a disconnection mode for power filters and filter-compensating circuits with reproduction of real currents and voltages.

Claims (2)

1. A device for testing switches for disconnecting a capacitive current containing auxiliary and test switches, the first terminals of which are interconnected, the reactor, the first transformer and the second transformer, the primary winding of which is connected to a voltage source, and the first output of the secondary winding of which is connected to the first the output of the first capacitor, characterized in that, in order to increase the reliability of the test results, it is equipped with a second capacitor and a switching element, the first terminal of which is connected to the second terminal of the first capacitor, and the second terminal of which is connected to the first terminal of the secondary winding of the first transformer, the second terminal of which connected to the second output of the auxiliary switch, the second output of the secondary winding of the second transformer is connected to the first terminals of the auxiliary and test switches, The first terminal of the second capacitor is connected to the first terminals of the first capacitor and the secondary winding of the second transformer, the second terminal of the second capacitor is connected to the second output of the switch being tested, and the reactor is connected to the primary terminals of the first transformer. 2. The device according to claim 1, about t l and expanding the field of application by enabling the operation of the power filters and filter compensating devices, connecting the primary windings of the first transformer to the reactor via the additionally introduced third capacitor, and connecting the second terminal of the second capacitor to the second output of the switch to be tested through the additionally introduced restoring circuit voltage, consisting of two parallel branches, one of which includes the second reactor, and the second is a series-connected resistor and a fourth capacitor. g em About rw. J 6 ig. 2