SU503191A1 - Synthetic test circuit for high voltage circuit breakers - Google Patents

Description

one

This invention relates to high-voltage, high-current electrical engineering. The synthetic circuit is designed to test the breaking capacity of high voltage AC switches, especially high breaking capacity switches.

Synthetic circuits for testing high-voltage circuit breakers are known, which contain a source of full current of industrial frequency undervoltage, a high-voltage source containing a series-connected capacitor, a reactor and a switching element, auxiliary and test switches, an impedance to form a restoring voltage.

The disadvantages of the known circuits are the need to use a special additional high-speed circuit breaker, the presence of at least two capacitor banks charged from different sources and to different nanoparticles whose energy cannot be used most optimally, the presence of at least two different inductances, the complexity setting up the circuit and testing, there is a significant difficulty in suppressing non-stationary transients during commutations in the process of reproducing livayuschegos nanr voltage. However, the costs of constructing three-loop circuits for testing powerful modern circuit breakers are significantly lower than the cost of building dual-loop circuits with similar test capabilities.

The aim of the invention is to increase test power and increase test equivalence. This is achieved by connecting in parallel to the high voltage source an additional chain of series-connected capacitor, reactor and switching element, moreover

the capacitors and reactors of the high voltage source and the additional circuit are connected by a flexible switching element, for example, a spark gap. Practically, such a circuit is obtained by dividing the oscillating LC-circuit of the source of the restoring voltage into two, as a rule, identical parts, which can be connected in succession or in parallel.

The switching gaps can be made in the form of spark gaps, shunted by valves, and an additional switch can be switched on in series with the auxiliary switching element.

impedance.

The drawing shows the described synthetic scheme. It contains a source of current of industrial frequency, auxiliary 2 and test 3 switches, impedances 4 and 5, CiZ-i and parts of the oscillating circuit of a source of restoring voltage, a rectifying device (valve) 6 (for example, a semiconductor diode), controlled by spark intervals 7, 8, and 9; and protective igniting devices 10 and 11 of controlled spark gaps.

The drawing shows a synthetic circuit with the connection of a source of restoring voltage in parallel to the test switch. Similarly, a circuit can be constructed with a high-frequency source connected in parallel with an auxiliary switch. Impedance 4 can be made of two parts and connected in parallel to the reactors LI and LZ Scheme works as follows.

After connecting to the chain from the test 2 and auxiliary 3 switches of the power source of the industrial frequency 1, a command is issued to turn off the switches and at the required time before the last condition of the power frequency zero current transfer conditions start, the spark gaps 7 and 8 are triggered. time through the arc of the tested switch begins to flow a sinusoidal current of increased frequency (superimposed on the current of industrial frequency), determined by the parameters of the oscillating circuit at parallel Yelnia connection of its two parts (LiCi and LzCz). In the general case, Ci and, therefore, the high voltage circuit has a capacitance of 2C and in1,.

Induction Li and LZ

ductivity -L.

calculated in such a way as to provide the necessary speed of approaching the short circuit current to zero in the switch being tested.

After zeroing the current in the switch under test (the auxiliary switch is disconnected earlier), the first voltage recovery stage is determined, which is determined by the impedance

4 and a loop inductance equal to -L.

At the same time, after recharging the capacitors Ci and Cz, the spark gaps 7 and 8 turn out to be shunted valves 6 (the polarity of switching on the valves is chosen opposite to the polarity of the initial charge of the capacitors Ci and C-), the voltage recovery stops at the initial intervals and they restore electrical strength. If necessary, a device for de-ionizing plasma decomposition products (for example, blasting, etc.) can be used to speed up the process of restoring the strength of the gaps.

At this recovery stage, the capacitance of a high-frequency source capacitor battery is the sum of the capacitances of the two parts of the oscillating circuit (Ci | -C2 2C). This fulfills the requirement of a significant excess of the source capacity of the capacity of the forming device.

Thus, in the initial stage of voltage recovery in the so-called stage of mutual influence between the switch and the network, i.e., in the time range, while the arc in the tested switch retains its electrical conductivity, the processes in the proposed scheme fully correspond to the same

processes in dual circuit with a very powerful capacitor battery.

The full magnitude of the restoring voltage — the second stage of the restoration — is provided by starting the spark

gap 9 at the time point when the charging of the impedance capacitors 4 had already occurred. Since at that moment the charging current of the resistance capacitances 4 through the valves 6 approached zero, and the spark gaps 7 and 9 recovered the electrical strength, the parts of the oscillating circuit LiCj and LzCs are turned on in series. In the newly formed loop, the recovery process is determined by

impedance 4 (and also, if necessary, additional impedance 5, connected in series with the spark gap 9, and inductance of the circuit. This makes it possible to significantly reduce the impedance capacitance 4 (and, as a result, the power of the main capacitor battery) compared to the known bypass circuits and three-circuit schemes.

In addition, the principle of operation of the proposed synthetic circuit makes it easy to form a four-parameter reconstructive voltage characterized by a rapid increase in the initial stage (in our case, the inductance of the circuit in this

stages -) and a slower increase

in the subsequent longer stage of stress recovery (in our

In this case, the inductance of the circuit increases four times and, in addition, additional resistance can be connected).

In the proposed scheme, at all stages the process of restoring the switching of its elements is carried out at zero current values. This achieves the possibility of avoiding the occurrence of any non-stationary processes caused by switching. The power of the capacitor bank of the oscillating circuit is much lower than in the corresponding two-circuit and well-known three-circuit circuits, due to a more rational use of the circuit elements. Tuning the circuit is not difficult, since both parts of the oscillating circuit are usually selected with the same parameters. The scheme is easy to calculate. The primary voltage of the capacitor charge of the circuit parts is approximately half the magnitude of the rotating voltage.

A switching element made in the form of a spark gap, shunted by a valve, makes it possible to significantly simplify the process of control of the circuit. At the same time, a relatively high application current flows through the spark gaps 7 and 8, and a relatively small voltage recovery current flows through the valves. To protect the valves selected for low current parameters, additional devices (10 and 11) can be introduced that trigger spark gaps connected in parallel to the valves when the current exceeds (or its derivative) above the given in emergency conditions (for example, during re-ignition arc in the test switch). Perhaps, another switching element is also used, which provides for synchronous switching on and off of circuit elements (for example, high-speed switches, thyristors with counter-parallel switching, etc.).

The proposed circuit can be used for testing apparatus when disconnecting unreleased short circuits, on switching capacity and in cycles. In the first case, the artificial line is included in the same way as in the known bypass circuits. In the second and third cases, the required results are achieved by changing the triggering sequence of the spark gaps. The advantage of the circuit is the possibility

charging capacitors Ci and Cz with gates 6. In this case, the charging device is greatly simplified.

Claims (3)

1. Synthetic circuit for testing high-voltage circuit breakers, containing a source of full current of industrial frequency of low voltage, a source of high voltage with an increased frequency of current, containing a series-connected capacitor, reactor and switching element, auxiliary switch, impedance for forming a regenerating voltage, characterized in that, in order to increase the test power and increase the equivalence of the test, it is equipped with a parallel source of high voltage additional chain of series-connected capacitor, reactor and switching element, and capacitors and reactor The sources of the high voltage source and the additional chain are connected by an auxiliary switching element, for example, a spark gap. 2. The circuit according to claim 1, characterized in that, for the purpose of simplification, the switching elements are made in the form of controlled spark gaps, shunted by valves, for example, semiconductor diodes. 3. Scheme on PP. 1 and 2, characterized in that, in order to reproduce a predetermined shape of the restoring voltage, at least one impedance is connected in series with the auxiliary switching element. //  D 0