RU2230385C2 - Vacuum current switch - Google Patents

Abstract

FIELD: electrical engineering, power commutation equipment. SUBSTANCE: vacuum current switch includes arc chute and magnetic system in the form of permanent magnetic or coil put on axis of arc chute on side of any contact to form lateral-radial field. Value and structure of magnetic field are controlled with the aid of magnetic core made of ferromagnetic material with implementation of certain relation between diameter of magnet and outer diameter of ring contact. EFFECT: improved structure of magnetic field in intercontact gap which enhances cut-off capability of switch and reduces mass and size characteristics when permanent magnet is used. 10 cl, 3 dwg

Description

The invention relates to electrical engineering, namely to power switching equipment, and is intended for use in vacuum circuit breakers and contactors of direct and alternating current.

In AC and DC vacuum circuit breakers, arc chambers are widely used, equipped with a magnetic system that creates a magnetic field in the gap between the contacts when they open, which facilitates current interruption

Known vacuum current switch containing an arcing chamber with a "built-in" magnetic system [1]. In this switch, the formation of a magnetic field in the gap is ensured by the breaker's own current and complex segmentation of the disk contacts.

The disadvantages of this device are the structural complexity of the contacts and a narrow scope: the magnitude of the current must be significant to create a magnetic field.

A vacuum current switch is known [2], in which an independent magnetic system in the form of a coil located along the axis of the arcing chamber on the fixed contact side forms a predominantly axial field in the gap.

The disadvantage of this device is the shape of the magnetic field, which does not allow the efficient use of the device for switching DC.

The closest technical solution is a vacuum circuit breaker containing an arcing chamber with axial movable and stationary electrodes with end contacts mounted on the camera body, and a magnetic system containing two coils and forming a plane-uniform transverse axis between the contacts [3].

The disadvantages of this device are the shape of the magnetic field, which causes the arc to drift in crossed electric and magnetic fields in only one direction, and weight and size characteristics, which are increased due to the placement of coils on the sides of the chamber.

The technical result of the proposed technical solution is to increase the breaking capacity and improve the overall dimensions of the vacuum current circuit breaker.

The technical result is achieved in that in a vacuum current switch containing an arcing chamber with axial movable and stationary electrodes with end contacts fixed to the camera body, and a magnetic system forming a transverse field between the contacts, the magnetic system is located along the axis from one of the contacts and made forming a transverse radial field; moreover, the magnetic system is made in the form of a permanent magnet, the magnetic system is made in the form of a coil; the magnetic system contains a magnetic circuit; the magnet is located on the side of the stationary electrode, while the magnet does not cross the plane of the gap; the magnet is made in the form of at least one disk or ring, the outer diameter of the contact is larger than the outer diameter of the magnet; the part of the housing in contact with the magnet is made of ferromagnetic material; the magnetic circuit is made in the form of a disk or ring; the magnet is located in the cavity of the movable electrode.

The invention is illustrated by drawings, in which Fig. 1 shows a schematic section of a vacuum current circuit breaker with a magnetic system in the form of a permanent magnet, Fig. 2 is an example of a circuit breaker with a magnetic system in the form of a coil located at a fixed electrode, and Fig. 3 is an example the design of the switch with a magnet in the form of a disk located in the cavity of the movable electrode.

The switch contains an arcing chamber with a movable 3 and a fixed 4 electrodes with end contacts 1 and 2, respectively, while the electrodes are mounted on the camera body 5, part 7 of which is made of ferromagnetic material, and a magnetic system with a permanent magnet 6 and a magnetic circuit 8.

The switch operates as follows.

With closed contacts 1, 2 made of a non-magnetic material, such as chromium copper, direct current flows through them and electrodes 3, 4 made of a non-magnetic highly conductive material, such as copper. A magnetic system made, for example, of a permanent magnet located along the axis, generates a transverse radial (azimuthally uniform and mainly radial) magnetic field in the contact area. Such a field effectively breaks the arc that occurs when the contacts open, since, firstly, it makes it difficult for electrons to hit the anode due to their magnetization, and secondly, the column of the arc cannot drift in the azimuthal direction in crossed electric and magnetic fields and, therefore, it is pushed to the periphery (case 5, made, for example, of copper) by centrifugal force, and thirdly, in the magnetic field decreasing along the radius, the arc plasma as a diamagnet is also pushed to the periphery.

The circuit breaker will also operate efficiently on alternating current if the half-life is longer than the arc break time.

To reduce the size of the circuit breaker and ensure its efficient operation with small currents, less than a kiloampere, the magnetic system is made of a permanent magnet, for example, based on samarium-cobalt 6.

To work with currents of at least several kiloamperes and in intense thermal conditions, the magnetic system is made of an electromagnetic coil 9, for example, made of copper.

To increase the magnitude of the magnetic field in the gap and reduce the size of the magnet, the magnetic system contains a magnetic circuit 8, made, for example, of a ferromagnetic material - Armco iron.

To reduce the working temperature of the permanent magnet, it is located on the side of the stationary electrode, where heat dissipation is facilitated.

To ensure a high degree of azimuthal uniformity of the magnetic field in the gap, the magnet is made in the form of a disk or ring.

To increase the share of the radial component of the magnetic field in the gap, the outer diameter d _{c of the} contact is made larger than the outer diameter d _{m of the} magnet, d _m <d _c .

To increase the magnitude of the magnetic field in the gap, part 7 of the housing in contact with the magnet is made of a ferromagnetic material, for example, Armco iron.

To ensure greater azimuthal uniformity of the field, the magnetic circuit is made in the form of a disk or ring.

To reduce the size of the switch, the magnet is located in the cavity of the movable electrode.

Thus, the invention significantly improves the configuration of the magnetic field in the gap, which allows to increase the breaking capacity of the circuit breaker and reduces its overall dimensions when using permanent magnets.

Literature

1. Vacuum arcs. Theory and applications. / Ed. J. Lafferty. - M .: Mir, 1982, p. 398.

2. Jenkis J.E., Vacuum switch arc control // UK Patent Application GB 2233498 A, 1991.

3. Emtage P.R., Kimblin C.W., Gorman J.G. et. al. // IEEE Trans. Plasma Sci., 1980, vol. 8, No. 4, p. 314-319.

Claims (10)

1. A vacuum circuit breaker comprising an arcing chamber with axial movable and stationary electrodes with end contacts fixed to the camera body, and a magnetic system forming a field transverse to the axis between the contacts, characterized in that the magnetic system is located along the axis from one of the contacts and made forming a transverse radial field. 2. The vacuum current switch according to claim 1, characterized in that the magnetic system is made in the form of a permanent magnet. 3. The vacuum current switch according to claim 1, characterized in that the magnetic system is made in the form of a coil. 4. A vacuum current switch according to any one of claims 1 to 3, characterized in that the magnetic system comprises a magnetic circuit. 5. A vacuum current switch according to any one of claims 2 and 4, characterized in that the magnet is located on the side of the stationary electrode, while the magnet does not cross the plane of the gap. 6. A vacuum current switch according to any one of claims 2, 4 and 5, characterized in that the magnet is made in the form of at least one disk or ring. 7. A vacuum current switch according to any one of claims 2, 4-6, characterized in that the outer diameter of the contact is larger than the outer diameter of the magnet. 8. The vacuum current switch according to claim 4, characterized in that the part of the housing in contact with the magnet is made of ferromagnetic material. 9. A vacuum current switch according to any one of claims 4 to 8, characterized in that the magnetic circuit is made in the form of a disk or ring. 10. A vacuum current switch according to any one of claims 2, 4, 6 and 7, characterized in that the magnet is located in the cavity of the movable electrode.

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