RU2711002C1 - Discharge chamber with three electrodes and two spark gaps (versions) - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: invention relates to electric devices for protection against pulse overvoltage, for example, thunderstorms, in electric networks of alternating current with voltage below 1,000. Principle of operation of the invention is based on electric discharge. Disclosed is a discharge chamber consisting of three electrodes with dielectric elements arranged there between. Number of electrodes must be at least three. Number of spark gaps is not less than two.EFFECT: increased reliability of protection against excess overvoltage.2 cl, 4 dwg

Description

FIELD OF THE INVENTION

The present invention relates to electrical devices for switching current and protection against excessive overvoltages in electrical AC networks with voltage below 1000 V, for example, lightning, the principle of which is based on electrical discharge.

State of the art

From the copyright certificate RU 2661356 C1 dated 07/16/2018, a discharge chamber is known consisting of electrodes between which a dielectric element with an aperture is placed, at least one of the electrodes is provided with an aperture that has a valve configured to discharge the discharge products from discharge chamber, characterized in that at least one electrode has a recess in the surface facing the dielectric element, as well as to the other electrode, through an opening in the dielectric element, and the dielectric The element is adjacent to the electrode along the perimeter of the recess.

The disadvantage of such a spark gap is that such a discharge chamber has a high discharge initiation voltage. This disadvantage negatively affects equipment for which a discharge chamber can be used to protect against overvoltages. In addition, the presence of a cone-shaped recess in one of the electrodes significantly complicates the design of the discharge chamber.

Also known are gas-filled arresters consisting of two or more discharge chambers. The disadvantage of such arresters is the inability to transmit large pulsed currents characteristic of lightning discharges and the absence of the ability to suppress accompanying currents. These shortcomings make it impossible to use such arresters in power electrical networks.

Disclosure of Invention

The objective of the invention is to reduce the threshold (breakdown) of the discharge chamber, i.e. the magnitude of the overvoltage at which the development (initiation) of an electric discharge occurs without sacrificing a decrease in the duration of the accompanying current (in other words, an increase in the voltage at the end of the discharge).

The objective of the invention is solved using a discharge chamber with two consecutive spark gaps and three electrodes made of special graphite, copper-tungsten, copper-bismuth, copper-chromium or copper-beryllium alloys. The principle of operation is based on the breakdown of spark gaps upon reaching the voltage at the terminals of the discharge chamber of the breakdown voltage. In the initial stage of development, a sliding discharge passes along the end surface of the annular dielectric strip 2. In the future, it passes into an arc discharge, directly in the air gap. The accompanying current is prevented by the rather large value of the near-cathode (near-electrode) voltage drop and crushing of the electric arc into two parts (in 2 gaps).

The technical result is a low value of the breakdown voltage, as well as an increase in the extinction voltage of the electric arc in the discharge gaps, to provide the necessary ability to suppress the accompanying current.

The technical result is achieved due to the presence in the claimed device of two discharge gaps, each of which has a sufficiently small breakdown voltage (less than the permissible voltage class), due to the use of dielectric spacers made of solid dielectric, contributing to the initialization of the sliding discharge, as well as the use of in the discharge chamber of electrodes made of a material that provides a significant voltage drop when the discharge current flows and improves the damp conditions arc of the accompanying current in each of the discharge gaps.

The electrodes may be in the form of a disk or disk with a hole in the center, in an embodiment where a valve is needed to relieve pressure. The discharge passes along the surface of an annular dielectric located closer to the axis of the electrode.

The spark gap formed by adjacent electrodes has no exits to the external environment, and when a discharge passes, an instant pressure increase is formed in it, providing additional suppression of the accompanying current.

The development of a discharge inside spark gaps occurs along the surface of the dielectric insert, which ensures the discharge chamber operates at a lower voltage and allows to obtain good protection characteristics.

At the same time, the voltage at the end of the discharge rises due to the fact that the total distance between the extreme electrodes of the discharge chamber is greater than that of a spark gap with one spark gap. This leads to a decrease in the duration of the discharge due to an increase in the voltage at the end of the discharge. The present invention significantly improves the ability to protect equipment from overvoltage.

Brief Description of the Drawings

In FIG. 1 shows one of the manufacturing options of the claimed device in section, containing:

1 - Special graphite electrodes made in the form of a disk;

2 - Dielectric inserts or dielectric dividers;

3 - contact plates for current distribution and connection to the electric network.

4 - housing made of structural plastic.

The figure 2 shows a three-dimensional image of the discharge chamber without a valve for pressure relief.

1 - Special graphite electrodes made in the form of a disk;

2 - Dielectric inserts or dielectric dividers;

3 - contact plates for current distribution and connection to the electric network.

4 - housing made of structural plastic.

In FIG. 3 shows an embodiment of the inventive device with a valve for relieving pressure in a section.

1 - Special graphite electrodes made in the form of a disk;

2 - Dielectric inserts or dielectric dividers;

3 - Contact plates for current distribution and connection to the electrical network.

4 - Housing made of structural plastic.

5 - Valve cover for pressure relief;

6 - Pressure relief valve.

The figure 4 shows a three-dimensional image of the discharge chamber with a valve for pressure relief.

1 - Electrodes made of special graphite with a hole in the center;

2 - Dielectric inserts or dielectric dividers;

3 - Contact plates for current distribution and connection to the electrical network.

4 - Housing made of structural plastic.

5 - Valve cover for pressure relief.

6 - Pressure relief valve.

The implementation of the invention

In general terms, the claimed invention is a discharge chamber made in two versions.

1. A discharge chamber for switching current and protection against excessive overvoltages in AC electric networks with voltage below 1000 V, consisting of a housing with contact plates, between which at least three electrodes made in the form of a disk are arranged alternately one after another, and between the electrodes are located dielectric separators made in the form of a ring and adjacent to the electrodes, with the formation between the electrodes of the air space in the form of spark gaps that do not have access to the external environment.

2. A discharge chamber for switching current and protection against excessive overvoltages in AC electric networks with voltage below 1000 V, consisting of a housing with a valve for relieving high pressure between the electrodes, inside the housing there are contact plates, between which at least three are alternately arranged one after another electrodes made in the form of a disk with a hole in the center, and between the electrodes are dielectric dividers made in the form of a ring and adjacent to the electrodes, with the formation between the electrode E airspace as spark gaps.

The first invention will now be explained with reference to FIG. 1, which is a sectional view of a discharge chamber comprising two spark gaps in accordance with the present invention. A preferred embodiment of the discharge chamber and, accordingly, spark gaps in which many elements have axial symmetry and represent or contain disks or rings is described. However, it should be borne in mind that the spark gap and the discharge chamber in accordance with the present invention can be implemented in other form factors.

The discharge chamber in FIG. 1 comprises a housing 4, in which electrodes 1 are placed, separated at the edges by dielectric inserts 2, which may also be called dielectric separators.

The electrodes are made of graphite, a copper-tungsten alloy or other types of refractory conductive materials, and the dielectric separator is preferably made in the form of a ring of insulating materials with high electrical strength, for example, a heat-resistant polymer material (for example, fluoroplastic or mica). The surface shape of the separator is preferably flat.

The dielectric separator is located between the electrodes with adjoining to them and the formation of spark gaps between them. The fit is necessary to limit the volume of the discharge chamber, as well as to enable the formation of a discharge moving along the dielectric separator, which is possible only in the case of fit.

When passing the discharge in the gaps between the electrodes 1, an increased pressure is formed, which also contributes to the suppression of the accompanying current.

Upon receipt of overvoltage arrester on the electrodes, a sliding discharge begins to develop on the inner surface of the dielectric inserts 2 in contact with the electrodes 1 from the point of contact of the electrodes 1 and the dielectric inserts 2. Next, the discharge passes into an arc.

Due to the smaller thickness of the dielectric separator 2, the arc discharge begins to develop at voltages less than the arc discharge in a two-electrode spark gap with one spark gap. The magnitude of the overvoltage at which the arrester trips (i.e., an electric discharge develops in it) decreases and, as a result, the tripping threshold (breakdown) of the arrester decreases.

A second embodiment of the invention is explained with reference to FIG. 3, in which a section shows a discharge chamber containing two spark gaps, which differs from the previous version in that it is equipped with a valve for relieving high pressure (7) between the electrodes (5), and the electrodes made in the form of a disk additionally contain a hole in the center, also providing relief of high pressure.

The electrodes 5 are separated by edges of the dielectric inserts 2, which may also be called dielectric dividers.

The electrodes are mainly made of graphite, a copper-tungsten alloy or other types of refractory conductive materials, and the dielectric separator is preferably made in the form of a ring of insulating materials with high electrical strength, for example, a heat-resistant polymer material (e.g. fluoroplastic or mica). The surface shape of the separator is preferably flat.

The dielectric separator is located between the electrodes with adjoining to them and the formation of spark gaps between them. The fit is necessary to limit the volume of the discharge chamber, as well as to enable the formation of a discharge moving along the dielectric separator, which is possible only in the case of fit.

When the discharge passes in the spaces between the electrodes 5, an increased pressure is generated, which also contributes to the suppression of the accompanying current.

Upon receipt of overvoltage arrester on the electrodes, a sliding discharge starts to develop on the inner surface of the dielectric inserts 2 in contact with the electrodes 5 from the point of contact of the electrodes 5 and the dielectric inserts 2. Next, the discharge passes into an arc.

Due to the smaller thickness of the dielectric separator 2, the arc discharge begins to develop at voltages less than the arc discharge in a two-electrode spark gap with one spark gap.

The presence of a valve for pressure relief allows increasing the throughput of the pulse current due to the discharge of the products of combustion of the electric arc through the valves and reducing dynamic loads on the walls of the discharge chamber.

The claimed device in two versions makes it possible to provide a sufficiently low triggering voltage of the arrester while simultaneously providing a significant throughput of the pulse current and a good ability to suppress the accompanying current.

The claimed device (options) allows you to provide reliable protection against excessive overvoltage in electrical AC networks with voltage below 1000 V.

Claims (2)

1. A discharge chamber for switching current and protection against excessive overvoltages in AC electric networks with voltage below 1000 V, consisting of a housing with contact plates, between which at least three electrodes made in the form of a disk are arranged alternately one after another, and between the electrodes are located dielectric separators made in the form of a ring and adjacent to the electrodes, with the formation between the electrodes of the air space in the form of spark gaps that do not have access to the external environment. 2. A discharge chamber for switching current and protection against excessive overvoltages in AC electric networks with voltage below 1000 V, consisting of a housing with a valve for relieving high pressure between the electrodes, inside the housing there are contact plates, between which at least three are alternately arranged one after another electrodes made in the form of a disk with a hole in the center, and between the electrodes are dielectric dividers made in the form of a ring and adjacent to the electrodes, with the formation between the electrode E airspace as spark gaps.

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