RU2400855C1 - Vacuum current switch - Google Patents

Abstract

FIELD: electrical engineering. ^ SUBSTANCE: proposed switch comprises case separated by high-voltage insulator to make arc extinguish chamber with axial movable and fixed electrodes. Movable electrode is secured to said case by current lead and metal corrugation that separates chamber vacuum medium from ambient medium. Electrodes are furnished with circular contacts. Fixed circular contact has radial grooves arranged along the circumference to receive permanent ""-like magnets to form magnetic system. Contact surface of circular contacts along electrodes axes are located on the level of magnet pole planes. Separating isolators are arranged between electrode and permanent magnets and between circular contact and permanent magnets. ^ EFFECT: increased concentration of magnetic field in gap between contacts, reduced wear and better switching characteristics. ^ 1 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.

A vacuum current switch is known, comprising an arcing chamber with axial movable and fixed electrodes with end contacts fixed to the camera body, and a magnetic system forming a field transverse to the axis between the contacts. The magnetic system is located on the axis from the side of one of the contacts and is made forming a transverse radial field [RF Patent No. 2230385, IPC Н01Н 33/664, publ. 2004.06.10].

The disadvantage of this vacuum circuit breaker is the design of the central part of the camera housing located inside the fixed electrode with an annular contact. This part of the housing is electrically connected to a fixed contact, and the magnetic field near it is perpendicular to it, since it is axial in nature. The arc arising between the contacts when they open is pushed out of the working gap and can stably burn between the central part of the movable electrode and the central part of the housing located inside the stationary contact, since the electric and magnetic fields are parallel to the axis. Thus, the switching characteristics of the circuit breaker deteriorate: the value of the switching current decreases and the time of interruption of the arc increases.

The closest adopted for the prototype is a vacuum circuit breaker containing an arcing chamber with axial movable and fixed electrodes with ring contacts mounted on the camera body, and a magnetic system coaxial with it, containing a permanent magnet located along the axis from the side of the fixed electrode, and forming a field between the contacts of the transverse radial axis. The central part of the camera housing, located inside the fixed contact, is electrically isolated from the fixed contact [RF Patent No. 2291513, IPC Н01Н 33/664, publ. 2007.01.10.].

The disadvantage of this vacuum circuit breaker is the low magnetic field strength in the contact gap.

The objective of the invention is to increase the concentration of the magnetic field in the contact gap, reducing the electrical discharge erosion of the contacts and improving the switching characteristics.

The problem is solved due to the fact that the vacuum current switch contains, as in the prototype, an arcing chamber with axial movable and stationary electrodes with ring contacts. The electrodes are attached to the camera body, and the fixed electrode is attached using a current lead and corrugation, and coaxially to the ring contacts on the side of the fixed electrode is a magnetic system containing a permanent magnet and forming a transverse radial axis between the contacts.

According to the invention, in a fixed ring contact from the side of its attachment to the electrode, radial grooves are made uniformly spaced around the circumference, in which U-shaped permanent magnets are located, isolated from the fixed electrode and the fixed ring contact. The contact surface of the ring contacts along the axis of the electrodes is located at the level of the plane of the poles of the magnets.

In the proposed vacuum current circuit breaker due to the fact that the permanent magnets are U-shaped and evenly spaced around the circumference of the stationary ring contact, the concentration of the magnetic field between the ring contacts increases. The electrodynamic effect on the electric arc is increasing, which increases its speed of movement between the ring contacts, and consequently, the erosion of the contacts is reduced and the switching characteristics are improved: the circuit breaker service life is extended and the arc interruption time is reduced.

Figure 1 schematically depicts a vacuum current switch and a magnetic system located on a fixed electrode, where aa is a sectional view from above, bb is a sectional view from below.

The vacuum current switch contains a housing 1, separated by a high-voltage insulator 2, forming an arcing chamber with axial movable 3 and fixed 4 electrodes. The electrodes 3 and 4 can be made of highly conductive material, such as copper. On the one hand, the movable electrode 3 is attached to the housing using a current lead 5 and a metal corrugation 6, which separates the vacuum medium of the chamber from the environment. The electrodes 3 and 4 are provided with ring contacts 7 and 8. The ring contacts can be made of non-magnetic material, for example, molybdenum. In the ring contact 8 there are made radial grooves uniformly spaced around the circumference, into which the U-shaped permanent magnets 9 are inserted, forming a magnetic system. Permanent magnets can be made on the basis of samarium - cobalt. The number of permanent magnets depends on the diameter of the ring contact 8 and the width of the permanent magnet 9. The contact surface of the ring contacts 7, 8 along the axis of the electrodes 3, 4 is at the level of the plane of the poles of the magnets 9. The separation insulators 10 are placed between the electrode 4 and the permanent magnets 9, and between the ring contact 8 and the permanent magnets 9.

The vacuum circuit breaker operates as follows.

With closed ring contacts 7, 8, an electric current flows from electrodes 3, 4 from current lead 5. The magnetic system generates a magnetic field radial relative to the axis of the ring contacts in the plane of connection of the movable 7 and stationary 8 ring contacts. When the ring contacts 7, 8 are opened between them, an electric arc lights up, while the corrugation 6 is compressed and the tightness of the arcing chamber is ensured. Mechanical efforts on the arc arising from the interaction of the electric current of the arc and the transverse magnetic field move it along the contacting surface of the ring contacts 7 and 8. Under the action of centrifugal force, the arc moves along the radius and is pushed out of the contact gap. Thus, the arc does not locally overheat the contacting surface of the ring contacts 7, 8, which ensures their uniform and minimal wear. Moving, the arc quickly cools and goes out.

Claims (1)

A vacuum current switch containing an arcing chamber with axial movable and fixed electrodes equipped with ring contacts, the electrodes are attached to the camera body, the movable electrode being attached with a current lead and corrugation, and a magnetic system containing a permanent magnet is coaxial with the ring contacts on the side of the fixed electrode and forming a field between the contacts of the transverse radial axis, characterized in that in a stationary ring contact from the side of its attachment to the electrode in full radial slots uniformly arranged along the circumference, which are arranged in U-shaped permanent magnets are isolated from the fixed electrode and a fixed annular contact, wherein the contact surface contacts the annular electrode axis located at the plane of the magnet poles.

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