RU2230386C2 - Vacuum current switch - Google Patents

Abstract

FIELD: electrical engineering, power commutation equipment, D C and A C contactors. SUBSTANCE: magnetic system in proposed vacuum current switch comes in the form of two permanent magnets or coils placed outside of arc chute on axis of electrodes and forms radial magnetic field lateral to axis of electrodes which enables arc caused by break of contacts to be cut effectively. Value and form of magnetic field are secured with the use of magnetic circuit and implementation of certain relation between diameters of magnet and ring contact. EFFECT: enhanced cut-off capability of switch, reduced mass and size characteristics of switch when permanent magnets are used. 5 cl, 2 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 DC and AC 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 the interruption of current.

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 contacts.

The disadvantages of this device are the narrow scope, since the current must be significant to create a magnetic field, and a strong spatial inhomogeneity of the magnetic field arising from the localization of the arc when the contacts open, which does not allow creating an azimuthally uniform radial field in the gap.

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

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. comprising an arcing chamber with axial movable and stationary electrodes with end disk contacts fixed to the camera body, and a magnetic system containing two coils located outside the chamber at its lateral surface and forming a plane-uniform transverse axis field 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 fixed electrodes with end contacts mounted on the camera body, and a magnetic system consisting of two magnetic field sources located outside the camera and forming a transverse axis between the contacts field, the magnetic system is made forming a radial field, and the magnetic field sources are located along the axis of the electrodes, while the contacts have a circular shape, and the source magnetic field nicknames are made in the form of permanent magnets, magnetic field sources are made in the form of coils; the magnetic system contains at least one magnetic circuit; the diameter of the magnet is less than the inner diameter of the contact.

The invention is illustrated by drawings, where in Fig.1 shows a schematic section of a vacuum current circuit breaker with a magnetic system in the form of permanent magnets; figure 2 is an example of a circuit breaker with a magnetic system in the form of coils.

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 housing 5 of the camera; and a magnetic system with permanent magnets 6, 7 and magnetic circuits 8, 9.

The switch operates as follows.

With closed contacts 1, 2 made of non-magnetic refractory material, such as molybdenum, direct current flows through them and electrodes 3, 4 made of non-magnetic highly conductive material, such as copper. A magnetic system made, for example, of permanent magnets located along the axis of the contacts forms an azimuthally uniform, radial magnetic field in the contact area. Such a field effectively terminates 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 strictly in the azimuthal direction in crossed electric and magnetic fields and, therefore is pushed to the periphery (case 5, made, for example, of stainless steel) 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 frequency of the current is less than the reverse arc break time.

To reduce the size of the circuit breaker and ensure its effective operation with small currents, less than a kiloampere, the magnetic system is made of permanent magnets, for example, based on samarium-cobalt 6, 7.

To work with currents of at least several kiloamperes and in intense thermal conditions, the magnetic system is made of an electromagnetic coil 10, 11, 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 magnetic cores 8, 9, made, for example, of a ferromagnetic material - Armco iron.

To ensure better plasma ejection to the periphery, the diameter of the magnets is made smaller than the diameter of the contacts, which allows the formation of a magnetic field decreasing in radius in the gap.

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 switching devices abroad. - M., Informelectro, 1982. Grobekatthofer H. D., Kruska M., Wirtschaftlichkeit der Vakuumleistungsschalter 3AF. - Siemens. - Energietechnic, 1981, 3. Beicheft Vacuumschaftechnic fir Mittelspannung, 32-35.

2. Jenkis J.E., Vacuum switch arc control / UK Patent Application GB 2 233 498 A, 1991.

3. Emtage P.R., Kimblin C.W., Gorman J.G. et. al. // IEEE Trans. Plasma Sci., 1980, vol. 8, 4, p. 314-319.

Claims (5)

1. A vacuum current switch comprising an arcing chamber with axial movable and fixed electrodes with end contacts mounted on the camera body, and a magnetic system consisting of two magnetic field sources located outside the camera and forming a field transverse to the axis between the contacts, characterized in that the magnetic system is made forming a radial field, and the sources of the magnetic field are located along the axis of the electrodes, while the contacts have an annular shape. 2. The vacuum current switch according to claim 1, characterized in that the magnetic field sources are made in the form of permanent magnets. 3. The vacuum current switch according to claim 1, characterized in that the magnetic field sources are made in the form of coils. 4. A vacuum current switch according to any one of claims 1 to 3, characterized in that the magnetic system contains at least one magnetic circuit. 5. A vacuum current switch according to any one of claims 2 and 4, characterized in that the diameter of the magnet is less than the internal diameter of the contact.

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