RU2464663C2 - CONTACT SYSTEM OF VACUUM ARC-QUENCHING CHAMBER FOR VOLTAGE OF 100 kV - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: contact system of a vacuum arc-quenching chamber comprises mobile and fixed contact units, every of which consists of a current contact jaw in the form of a rod, a contact part with a flat surface of contact, an inductor in the form of a split ring from a material with high electric conductivity and a bushing from a material with low electric conductivity. The inductor and the bushing are arranged between the contact part and the current contact jaw and are connected with them. The bushing is installed inside the inductor and coaxially with it. The contact part is shaped as a cup turned upside down with a side cylindrical surface covering the inductor in the form of the split ring. A transition between the flat surface of contact and the side cylindrical surface is arranged with a radius of rounding of at least 5 mm. As a result at edges of the contact part and ring inductor there is no high intensity of electric field, which reduces or eliminates probability of vacuum gap breakthrough between opened contacts. Besides, vacuum breaker design will also become more compact and less material-intensive.

EFFECT: development of a contact system with high breakthrough voltage of gaps between open contacts, which makes it possible to reduce travel of contacts and dimensions of a vacuum arc-quenching chamber.

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Description

The invention relates to the field of electrical engineering, namely to vacuum circuit breakers and is used in vacuum arcing chambers of high voltage.

The main element that provides switching and high-voltage characteristics of vacuum circuit breakers are vacuum interrupter chambers (VDC), the characteristics of which, in turn, are largely determined by the design of the contact system (CS). At present, in the VDK for high voltage (over 35 kV), exclusively CSs are used that create a longitudinal magnetic field, where the magnetic induction vector is parallel to the current vector of the electric arc. A longitudinal magnetic field created by a CS, when current flows through it, provides a diffuse form of burning an electric arc, which occurs when the contacts open. The diffuse shape of the electric arc is characterized by low voltage and uniform dispersion over the surface of the CS, due to which there is no excessive heating of the surface of the CS, and when the current passes through zero between open contacts, the voltage is restored, that is, the current is successfully turned off in the CS of the VDK. An additional requirement for CS for VDK for voltages above 35 kV is that open contacts must withstand higher voltages in the off state, so the configuration of the CS should be such that the electric field on its surfaces does not exceed a critical value.

In the technical solution (patent JP 2010113821 A, IPC: H01H 33/66, published May 20, 2010) [1] a CS for a high-voltage VDK is proposed, in which a longitudinal magnetic field is created by an inductor having a cup shape with several oblique slots in its walls. These slots direct the current along helical lines, as a result of which the current creates a longitudinal magnetic field. The inductor is connected to the contact part, having the shape of a round and flat disk, and is externally covered by a screen made of stainless steel, which serves to level the electric field at the sharp edges of the grooves.

The disadvantage of this design KS is that the inductor used in it has a large size in length, and the magnetic field created by the helical current lines is limited in size. In addition, the external screen does not cover the side edges of the contact part itself, on which an increased electric field strength occurs.

Closest to the proposed solution is the design proposed in (patent US 5777287 A, IPC: H01H 33/66, published 07.07.1998) [2]. In it, the contact system contains movable and fixed contact nodes, which in the text below will also be called contacts, each of which consists of a current supply in the form of a rod, a contact part in the form of a circular disk with a flat contact surface, and an inductor in the form of a split ring made of high-material material electrical conductivity and bushings of a material with low electrical conductivity, and the inductor and the sleeve are located between the contact part and the current lead and connected to them, while the sleeve is installed inside the inductor and coaxial with it.

The disadvantage of this design is that at the edges of the circular disk of the contact part and the ring inductor there is an increased electric field strength, which can lead to breakdown of the vacuum gap between the separated contacts.

The technical task of the invention is the creation of KS VDK voltage of 110 kV and higher with a high breakdown voltage of the gaps between the separated contacts by reducing the electric field strength on the surfaces of the KS.

The technical result achieved by the invention is to create a contact system for a vacuum interrupter chamber containing movable and fixed contact nodes, each of which consists of a current supply in the form of a rod, a contact part in the form of a circular disk with a flat contact surface, and an inductor in the form of a split ring made of material with high electrical conductivity, bushings of a material with low electrical conductivity, and the inductor and the sleeve are located between the contact part and the current lead and connected to it and, while the sleeve is installed inside the inductor and coaxially with it.

The stated technical problem is solved due to the fact that the contact part has the shape of an inverted bowl with a cylindrical side surface covering the inductor in the form of a split ring, and the transition between the flat contact surface and the cylindrical side surface is made with a fillet radius of at least 5 mm.

Due to this, at the edges of the contact part and the ring inductor there is no increased electric field strength, which reduces or eliminates the possibility of breakdown of the vacuum gap between the separated contacts.

The design of the COP is illustrated by figures 1 and 2. Figure 1 - General view of the contact system VDK. Figure 2 - sections of the nodes of the COP of the VDK. The positions in figure 1 and figure 2 are indicated:

1 - current supply of the movable contact node;

2 - current supply of a fixed contact node;

3 - contact detail in the form of an inverted bowl;

4 - inductor in the form of a split ring;

5 - sleeve.

The VDK contact system contains: movable and fixed contact nodes (contacts), each of which consists of a current supply made in the form of a rod, a contact part in the form of an inverted bowl 3, an inductor in the form of a split ring 4 from a material with high electrical conductivity and a sleeve 5 from material with low electrical conductivity, and the inductor in the form of a split ring 4 and the sleeve 5 are located between the contact part in the form of an inverted bowl 3 and a fixed current lead 2 or a movable current lead 1. All parts are connected to each other m by soldering. The contact part in the form of an inverted bowl 3 has a flat contact surface S, conjugated with a fillet radius R of at least 5 mm, with a lateral cylindrical surface P covering the inductor 4 (Fig. 1).

The contact system works as follows: during the shutdown operation, the circuit breaker drive through a system of shafts, levers and insulating rods (not shown in the figures) opens the contacts of the airborne electrical system to a distance N. An electric arc arises in the intercontact vacuum gap, which burns in metal vapor, from which the contact piece is made in the form of an inverted bowl 3 (usually the composition is chrome-copper). The current I in the contact system flows as follows: from the movable current supply in the form of a rod 1 it enters the inductor in the form of a split ring 4 and, passing along its ring, creates a longitudinal magnetic field with induction B. in the gap between the contacts of the CS, then through the protrusion at the end of the ring the inductor current flows into the contact part in the form of an inverted bowl 3. In a stationary contact, the current I flows in the same way: from the contact part in the form of an inverted bowl 3, the current flows into the inductor in the form of a split ring 4, flows through its ring and falls down in the current lead fixed contact. The directions of the magnetic field induction vectors B created by the inductors of the movable and fixed contacts coincide. Thus, the magnetic field induction vectors in the contact gap are summed. A longitudinal magnetic field provides a diffuse form of burning an electric arc, while the electric arc is uniformly dispersed over the surface of the contact part in the form of an inverted bowl 3. As mentioned earlier, a vacuum arc in a longitudinal magnetic field has a diffuse shape, which does not cause strong heating of the contact surfaces. When the alternating current passes through zero, the arc goes out, and voltage is restored between the contacts. The operation of turning off the current KS VDK successfully completed.

When current flows in the CS, it mainly passes through the inductor in the form of a split ring 4, since it is made of a material with high electrical conductivity, and only a small part passes through the sleeve 5, since it is made of a material with low electrical conductivity (for example, stainless steel ) The purpose of the sleeve 5 is to absorb the mechanical loads that occur during the switching operation, when the contacts of the CS are closed at a high speed, and then pressed to reduce the transient electrical resistance and ensure electrodynamic stability.

After turning off the current, the contact gap is exposed to an electric field. Moreover, in the class of 110 kV, the peak of the recovering voltage between the open contact nodes of the CS can reach 200 kV. To withstand such a voltage, the surface of the COP should not have sharp angles or edges at which the concentration of the electric field. In the present invention, the contact part in the form of an inverted bowl 3 with its lateral cylindrical surface P shields the sharp edges of the inductor in the form of a split ring 4. The transition from the flat contact surface S to the lateral cylindrical surface P is made with a fillet radius R of at least 5 mm. This design of the COP allows you to minimize the electric field strength. In addition, the proposed design is compact, which saves the internal volume and dimensions of the VDK, and the magnetic field generated by the inductor in the form of a split ring has a large value, since the turns are extremely close to the contact surface.

Thus, the proposed technical solution allows you to create a contact system with a longitudinal magnetic field for a vacuum arcing chamber for high (up to 110 kV) voltage. The proposed COP is easy to manufacture and technologically advanced.

Vacuum circuit breakers currently occupy a leading position among other types of switching devices in the voltage class 10-35 kV due to such advantages as:

- environmental cleanliness;

- high switching resource;

- the possibility of operation at temperatures of -60 ° C and below.

In recent years, they also began to be used in the voltage class of 110 kV and create competition for gas-insulated apparatus.

The positive effect of the invention also lies in the fact that the COP allows you to reduce the contact path and the dimensions of the airborne forces. In addition, the design of the vacuum circuit breaker will also become more compact and less material-intensive.

Information sources

[one]. Patent JP 2010113821 A, IPC: H01H 33/66, published 05/20/2010.

[2]. Patent US 5777287 A, IPC: H01H 33/66, published 07.07.1998.

Claims (1)

A contact system for a vacuum interrupter chamber comprising movable and fixed contact nodes, each of which consists of a current supply in the form of a rod, a contact part with a flat contact surface, an inductor in the form of a split ring made of a material with high electrical conductivity, a sleeve made of a material with low electrical conductivity, and an inductor in the form of a split ring and the sleeve are located between the contact part and the current lead and connected to them, while the sleeve is installed inside the inductor and coaxially with it, I distinguish The contact part has the shape of an inverted bowl with a side cylindrical surface covering the inductor, and the transition between the flat surface and the side cylindrical surface is made with a fillet radius of at least 5 mm.

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