JPS5826605B2 - Vacuum cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic pressurization type vacuum breaker suitable for opening and closing large current paths.

A conventionally used vacuum breaker is constructed as shown in FIG.

That is, the vacuum container 1 is formed of an insulating tube 2 and flanges 3 and 4 that seal both ends of the insulating tube 2.
A fixed electrode 7 and a movable electrode 8 are supported facing each other in the vacuum vessel 1 so as to be detachable by a fixed rod 5 and a movable rod 6, which respectively pass through the vacuum chamber 1 in an airtight manner.

The fixed rod 5 is fixedly sealed to the 7 flange 3, and the movable rod 6 is movably supported by the flange 4 via a bellows 9 that keeps its movable part airtight. Terminal 10.1 connected to the external circuit
1 is provided.

Here, the inside of the vacuum container 1 is evacuated and sealed to an appropriate degree of vacuum, and due to the pressure difference (hereinafter referred to as bellows pressure), a force is constantly acting on the movable rod 6 in the direction of its closing. When the contact is opened, an opening force is applied to the movable rod 6 to resist the bellows pressure, and when the contact is closed, the bellows pressure alone is not enough to obtain the desired contact force, so an operating section (not shown) is provided that applies contact force to the movable rod 6. The vacuum breaker is operated by driving this operating section.

In such a configuration, when the vacuum breaker I1 is turned on from the open state, the movable rod 6 moves in the closing direction, and the movable electrode 8 approaches the fixed electrode T.

When the distance between the two electrodes approaches a certain value or less,
Unable to withstand the voltage between the electrodes, dielectric breakdown occurs and an arc 12 is generated.

This input arc 12 short-circuits the two electrodes, so
The input current ■ is terminal 10, fixed rod 5, fixed electrode 7
, flows through the movable electrode 8, the movable rod 6, and the terminal 11 to an external electrical circuit.

In this case, current components Ia and Ib flow in the fixed electrode 7 and the movable electrode 8 in parallel to the input arc 12 in a direction substantially perpendicular to each other and in opposite directions, as shown in the figure.

The firing position of the input arc 12 is determined by the parallel current component I, which is determined by the electrode surface condition or the abutting condition of both electrodes.
The composite magnetic field generated by a, Ib and the input arc 12 moves the input arc 12 to the outer edge of the electrode.

Here, since the parallel current components Ia and Ib are parallel and in opposite directions, the fixed electrode 7 and the movable electrode 8 repel each other,
An electromagnetic repulsive force F1 acts on the movable electrode 8 in the opening direction, that is, in the direction of the arrow.

Therefore, this electromagnetic repulsive force F1 acts in a direction that prevents the closing operation of the vacuum breaker, thereby inhibiting the closing operation.

Then, this electromagnetic repulsion force F1 is a parallel current component Ia
Since it is proportional to the product of Ib and Ib, it is most disadvantageous when a current several tens to hundreds of times higher than normal energization flows, such as when turning on, and the contact pressure of the operating section is not functioning sufficiently.

Note that this electromagnetic repulsion force F1 acts not only when the power is turned on but also during normal energization, so it cannot be ignored, especially when applying a large current, and it is necessary to increase the contact force of the operating part to ensure the specified contact force. There is.

In this way, in order to turn on the vacuum breaker against the electromagnetic repulsion force F1 and maintain a large current flowing, a strong contact force is required on the operation section, and the contact force of the ordinary operation section is If the repulsion force F1 cannot be resisted, the applied arc 12 will continue for an unreasonably long time, causing abnormal wear of the fixed electrode 7 and movable electrode 8, or the phenomenon that both electrodes may become welded and cannot be opened, resulting in a large current capacity of the vacuum breaker. This was a hindrance to development.

Furthermore, since the thickness of the movable rod 6 is restricted by the diameter of the bellows 9, the temperature rise of the movable rod 6 also poses a problem at large currents.

This invention was made to eliminate these drawbacks, and it suppresses the electromagnetic repulsive force generated between the electrodes, and effectively creates an electromagnetic repulsive force that acts in the direction of inserting the movable electrode by the current flowing through both electrodes. This provides a vacuum breaker that operates reliably with relatively small mechanical force (contact pressure).

An embodiment of the present invention will be described below.

In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, so a description thereof will be omitted.

In Fig. 2, 13 is a plurality of conductors made by laminating strip-shaped conductors made of thin copper plates and bending them into a U-shape.
The parallel parts 13a, 13b of each conductor 13 are arranged in a direction perpendicular to the direction of contact and separation of the movable electrode 8, and the parallel parts 13a, 13
b are opposed in the approaching and separating direction, and their open ends are connected to the outer edge of the movable electrode 8 and the flange 4, respectively.

Note that the operating stroke of the movable rod 6 is absorbed by this bent portion, that is, the flexible portion 13c.

14.14 is a terminal that passes through the flange 4 in an airtight manner and is connected to the conductor 13. Connection to the external electric circuit is made through this terminal 14.1.
4 and a terminal 10 of a fixed rod 5 are used.

In the above configuration, when the vacuum breaker I1 is turned on, the movable rod 6 moves in the closing direction, the movable electrode 8 approaches the fixed electrode 7, and when the gap between the two electrodes reaches a certain value or less, dielectric breakdown occurs. , and an injection arc 12 is generated.

This input arc 12 short-circuits between the electrodes, and the input current flows through the terminal 10, the fixed rod 5, the fixed electrode 7, the movable electrode 8, the conductor 13, and the terminals 14, 14 to the external circuit.

In this case, a current component Ia that is almost perpendicular to the input arc 12 flows through the fixed electrode 7, but since no current path is formed in the movable rod 6, a current component that is parallel to and opposite to the current Ia flows through the movable electrode 8. There are no ingredients.

Therefore, there is no electromagnetic repulsion force acting between the two electrodes, and the closing operation of the vacuum breaker can be performed smoothly.

On the other hand, the current Ic flowing into the conductor 13 is
Since the directions are opposite at points a and 13b, the electromagnetic repulsion force F
2 will occur.

This electromagnetic repulsion force F2 pressurizes the movable electrode 8 toward the fixed electrode 7 side, that is, in the closing direction, as shown by the arrow in the figure, and assists the closing operation of the vacuum breaker, so that the closing arc 12 can be extinguished within a short time. .

As mentioned earlier, this electromagnetic repulsion force (pressure force) F2 is proportional to the product of the respective currents, so when the current reaches several tens to hundreds of times higher than normal energization, such as when turning on the current, Very effective.

It goes without saying that this electromagnetic repulsive force F2 acts even during normal energization, and in particular when a large current is energized, a sufficient contact force can be ensured with a small contact force.

By the way, in the above embodiment, the conductor 13 is formed by laminating thin copper plates and bending them into a U shape. However, the parallel parts 13a and 13b of this conductor 13 are made of thick steel plates, etc. It may be constructed of a flexible conductor such as a braided wire, and if the conductor 13 is formed into an annular shape, the electromagnetic repulsive force F2 acting on the movable electrode 8 will be applied uniformly, making its operation more stable.

Further, in the above embodiment, all of the current is passed through the conductor 13, but a part of the current may be diverted to the movable rod 6. Furthermore, the flexible portion 13c of the conductor 13 may be disposed on the bellows 9 side. You can also get the same effect.

As explained above, according to the present invention, a current path is provided between the outer edge of the movable electrode and the inner wall of the vacuum chamber on the movable electrode side, through which all or part of the current flowing through the fixed and movable electrodes flows in opposite directions. Since the conductors to be formed are connected, the electromagnetic repulsion between the two electrodes can be suppressed, and the electromagnetic repulsion acting on the conductor acts as a force that drives the movable electrode toward the fixed electrode. There is an advantage that the closing operation can be performed reliably with a relatively small mechanical force.

In the past, the electromagnetic repulsion force increases at an accelerating rate as the current flowing through the conductor increases, making it easy to increase the current capacity of the vacuum breaker, and eliminating problems such as abnormal wear or welding of the electrodes.

Furthermore, since the current flowing through the movable rod is zero or reduced, its temperature rise is suppressed, and the movable rod can be made of a material with excellent mechanical strength, such as stainless copper, to reduce its thickness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional vacuum breaker, and FIG. 2 is a sectional view showing an embodiment of the present invention. In the figure, 1 is a vacuum vessel, 2 is an insulating tube, 3.4 is a flange, 5 and 6 are fixed and movable rods, 7.8 is a fixed and movable electrode, 9 is a bellows, 13 is a conductor, 10 and 14
is a terminal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A fixed electrode fixed in a vacuum container, a movable electrode provided so as to be able to come into contact with and separate from the fixed electrode, and between the outer edge of the movable electrode and the vacuum container on the movable electrode side. , each having first and second current paths that are orthogonal to the direction of contact and separation of the fixed electrode and the movable electrode, are arranged parallel to each other, and have current flowing in opposite directions. A conductor is provided, and the electromagnetic repulsion force exerted by the current flowing through the first and second current paths of the conductor is made to act as a force for driving the movable electrode toward the fixed electrode. Vacuum breaker. 2. The vacuum breaker according to claim 1, wherein the conductor is formed in a U-shape. 3. The vacuum breaker according to claim 1 or claim 2, characterized in that the vacuum breaker is composed of a plurality of conductors. 4. The vacuum breaker according to claim 1 or 2, characterized in that the conductor is formed in an annular shape. 5. The vacuum breaker according to any one of claims 1 to 4, characterized in that the outer edge of the movable electrode is the outer edge on the opposite side of the contact surface of the movable electrode.