JPH0567414A - Vacuum valve - Google Patents

Abstract

PURPOSE:To enhance a voltage withstanding characteristic and elongate a switching service life by decreasing extension length and the number of ribs in a bellows of one side vacuum valve with respect to a bellows of the other side vacuum valve. CONSTITUTION:Vacuum vessels 10A and 10B are connected to each other by means of respective fixed current-carrying shafts 6A, 6B and a conductor 9, and contactable/separatable electrodes in the vessels 10A, 10B are connected in series. When they are incorporated in a vacuum circuit breaker, movable current-carrying shafts 5A, 5B are connected to an operating mechanism for driving. A bellows 7A having a shorter working distance, namely, the number of rib ridges being less and a total length being shorter, in comparison to a bellows 7B arranged in the vessel 10B is arranged in the vessel 10A. The bellows 7B having a longer extension rate and a longer total length is used as the other side bellows. The number of ribs and extension length of the bellows 7B are determined respectively about four times of those of the bellows 7A shorter in the total length.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve, and more particularly to a vacuum valve having two bellows.

[0002]

2. Description of the Related Art A vertical sectional view of a vacuum valve used in a conventional vacuum circuit breaker is shown in FIG. As shown in FIG. 1, the conventional vacuum valve has a fixed electrode 3A and a movable electrode 3B that can be brought into contact with and separated from each other in a vacuum container configured by closing both ends of an insulating cylinder 31 with a fixed flange 2A and a movable flange 2B. I am configuring. Here, the fixed electrode 3A is fixed to the tip of the fixed energizing shaft 35A, and is connected to the outside of the vacuum container via the fixed energizing shaft 35A. Similarly, the movable electrode 3B is fixed to the tip of the movable energizing shaft 35B, and is connected to the outside of the vacuum container via the movable energizing shaft 35B. The movable energizing shaft 35B is fixed to the movable flange 2C via the bellows 37, and when assembled in a vacuum circuit breaker (not shown),
The electrodes can be contacted and separated by an operation mechanism portion (not shown) while maintaining the vacuum in the vacuum container.

As is well known, since the vacuum valve utilizes the excellent dielectric strength of vacuum, the distance between the electrodes can be narrowed as compared with, for example, an SF ₆ gas circuit breaker using another insulating medium. The vacuum circuit breaker can be made compact. Also, the breaking capacity can be increased by improving the electrode structure.

On the other hand, in order to improve the breaking performance of the vacuum valve, it is necessary to suppress the local heating of the electrodes due to the arc generated between the electrodes, and the breaking performance is improved by suppressing the generation of abnormal charged particles due to the local heating. it can. As an electrode structure for this purpose, there is a method of applying a magnetic field parallel to the arc generated between the electrodes when the current is cut off. When this method is adopted, the arc generated between the electrodes uniformly spreads over the entire surface of the electrodes, so that local heating of the electrodes can be suppressed, damage to the electrodes can be reduced, and the breaking performance can be improved. On the other hand, there is a method of applying a perpendicular magnetic field to the arc generated between the electrodes. In this method, the concentrated arc of the high current arc is rotated on the electrode surface to improve the breaking performance.

By the way, with the progress of vacuum circuit breakers, it has been applied in recent years to open and close and break high voltage circuits.
For that purpose, it is necessary to increase the distance between the electrodes to increase the withstand voltage between the electrodes. At this time, in the method of applying a magnetic field perpendicular to the arc generated between the electrodes, the arc may be elongated and the arc may be ignited to the shield around the electrodes, and the breaking performance was not sufficient. .. However, when an electrode structure that applies a parallel magnetic field to the arc generated between the electrodes is adopted, a stable arc can be ignited between the electrodes by optimizing the magnetic field strength. Performance can be improved.

[0006]

In order to increase the distance between the electrodes, it is necessary to use a bellows 37 having a long working distance in FIG. 6, and in order to lengthen the working distance, the number of stages of bellows, that is, the bellows There are ways to increase the number of folds.

FIG. 7 shows the relationship between the operating life of the bellows and the operating distance, and FIG. 8 shows the relationship between the operating life of the bellows and the number of pleats. The operating life of the bellows is increased by decreasing the operating distance or increasing the number of pleats. The results shown in FIGS. 7 and 8 are obtained when the expansion and contraction amount of the folds of the bellows is almost the same for the entire bellows. As will be described later, when the operation speed is high, the folds are expanded and contracted uniformly. However, since it causes undulations, as will be described later, the operating life is significantly reduced from the results shown in FIGS. 6 and 7. The rate of decrease in the switching life increases as the operating distance increases.

The operating speed needs to be increased for the following reasons. First, in order to satisfy the breaking performance, it is necessary to make the insulation recovery speed between the electrodes faster than the transient recovery recovery voltage generated in the circuit that opens and closes the current. That is, it is necessary to operate the movable electrodes at high speed to increase the insulation recovery speed between the electrodes. Furthermore, if the opening speed at the instant when the current is cut off is slow,
The local concentration of the current occurs, the damage of the electrode increases, and the breaking performance is deteriorated. This is because the arc is concentrated as a property of a vacuum arc generated between short electrodes of several mm or less. Therefore, in order to improve the breaking performance, it is necessary to increase the opening speed at the time of opening. On the other hand, when the electrode is closed, if the closing speed is slow, the damage to the electrode increases. This is because in the region where the distance between the electrodes is short immediately before the electrodes contact each other when the electrodes are closed, the voltage of the circuit applied between the electrodes becomes higher than the dielectric strength between the electrodes, causing dielectric breakdown between the electrodes and Flows. At this time, since the arc is in a state where the distance between the electrodes is short, the current is concentrated and the electrodes are damaged as described above. The period from when the current starts to flow until the electrodes come into contact with each other is called pre-arc time. The longer the pre-arc time, the more the electrode is damaged. Since this pre-arc time is inversely proportional to the dielectric strength between electrodes, that is, the closing speed, it is necessary to increase the closing speed.

However, when the movable energizing shaft of the vacuum valve using a bellows having a large number of pleats is driven, the pleats of the entire bellows do not change uniformly in spacing, and the movement of the pleats is disturbed. This turbulence is, for example, when opening the electrode,
In the initial state, the intervals between the pleats of the bellows are uniform throughout, and the bellows folds move in the direction of compressing when opening, but when the opening speed is increased, only the electrode side of the bellows is opened at the opening moment. Compressed. This is because the folds on the flange side of the bellows are inertially delayed in starting the movement of the movable shaft. At this time, the amount of compression of the bellows on the electrode side is larger than the amount of compression that the entire bellows is uniformly compressed in a stable state after completion of opening. After that, the excessive compression state on the electrode side of the bellows moves to the pleats on the flange side due to the spring constant of the bellows. Since this shrinkage is larger than the amount of compression at the completion of opening,
After moving to the flange end of the bellows, it is reflected. For this reason, the excessively compressed region of the bellows is reflected at the end of the bellows after moving from the electrode side to the flange side of the flange, moves from the flange side to the electrode side, and at the end of the electrode side. Repeat the reflected motion. The excessive amount of compression of the folds due to this motion is attenuated as the motion is repeated. That is, the motion in the excessively compressed region repeats a waviness-like motion, and finally stabilizes at a uniform pitch upon completion of the contact opening. The exercises described above are
Similarly, when the electrode is closed, the motion in the region where the folds are extended is stabilized in the state of the uniform fold spacing after the completion of the closing of the electrode after repeating the undulating movement.

As described above, when the movement of the pleats of the bellows becomes uneven, the bellows fatigue increases due to the excessive expansion and contraction of the bellows and the actual number of expansions and contractions due to undulations.
Compared with the characteristics shown in FIGS. 7 and 8, the operating life is significantly shortened, which may lead to early fatigue fracture. As a result, when the bellows fatigue-fractures, a vacuum leak occurs in the vacuum container from the broken portion of the bellows, which shortens the opening / closing life of the vacuum valve. According to the results of experiments conducted by the inventors, it has been impossible to open and close the vacuum valve several hundreds of thousands times even if the number of bellows pleats is increased in a vacuum valve having an operating distance of several tens of millimeters. Therefore, in view of the above problems, an object of the present invention is to provide a vacuum valve having excellent withstand voltage characteristics and capable of extending the switching life.

[0011]

[Means and Actions for Solving the Problems] The first invention is
A vacuum valve equipped with a movable energizing shaft penetrating the bellows on one side of the vacuum container and a fixed energizing shaft penetrating on the other side of the vacuum container is connected with the fixed energizing shaft facing each other. By shortening the expansion and contraction length of the bellows with respect to the bellows of the vacuum valve on the other side and reducing the number of folds, the movable shaft penetrating the bellows of the vacuum valve on one side is operated at high speed, and the arc Prevents concentration and increases the withstand voltage value after opening with the bellows of the vacuum valve on the other side, slows the operation speed of the folds of this bellows, and prevents the number of expansions and contractions from increasing due to undulations, which has excellent withstand voltage characteristics and opening and closing life. Is a vacuum valve that has been extended.

According to a second aspect of the present invention, bellows are provided on both sides of the vacuum vessel, a movable current-carrying shaft penetrating the bellows is provided, a fixed electrode is provided at an intermediate portion of the vacuum vessel, and one bellows is attached to the bellows on the other side. By shortening the expansion and contraction length and reducing the number of pleats, the movable shaft penetrating one side of the bellows is operated at high speed to prevent the concentration of the arc immediately after the electrode is opened, and the bellows on the other side to prevent the resistance after opening. This is a vacuum valve that not only increases the voltage value but also lowers the operation speed of the folds of the bellows and prevents the number of expansions and contractions from increasing due to undulations, and has excellent withstand voltage characteristics and a long opening and closing life.

According to a third aspect of the present invention, bellows are provided on both sides of the vacuum container, a movable current-carrying shaft is provided so as to penetrate the bellows, and the bellows on one side is shorter than the bellows on the other side in terms of expansion / contraction length and the number of pleats. This allows the movable shaft penetrating the bellows on one side to operate at high speed to prevent the concentration of the arc immediately after the electrode is opened, and the bellows on the other side to increase the withstand voltage value after opening and It prevents the increase of the number of expansion and contraction due to the swell of the
This is a vacuum valve with an extended switching life.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. A sectional view of the vacuum valve of the first invention is shown in FIG. In FIG. 1, the vacuum valve is the first vacuum container 10A.
And a second vacuum container 10B connected in series to the vacuum container 10A by a connecting conductor 9. Each vacuum container 10A,
10B includes a pair of electrodes that can be contacted and separated, fixed electrodes 4A and 4B.
And the movable electrodes 3A and 3B are arranged. Of these, the fixed electrodes 4A and 4B are fixed to the fixed energizing shafts 6A and 6B and the tips, and the movable electrodes 3A and 3B are fixed to the tips of the movable energizing shafts 5A and 5B. Has been done. The movable energizing shafts 5A and 5B are hermetically connected to the movable flanges 2A and 2B via bellows 7A and 7B.

The vacuum vessel 10A and the vacuum vessel 10B are connected to the respective fixed current-carrying shafts 6A and 6B by a connecting conductor 9, and the electrodes which can be contacted and separated in the respective vacuum vessels 10A and 10B are connected in series. On the other hand, when incorporated in a vacuum circuit breaker, the movable energizing shafts 5A and 5B are connected to an operating mechanism (not shown) and driven.

Bellows 7A placed in the vacuum container 10A
Uses a bellows 7A having a shorter operating distance than the bellows 7B arranged in the vacuum container 10B, that is, a bellows 7A having a small number of folds and a short overall length. For the other bellows, a bellows 7B having a long expansion and contraction length and a long overall length is used. In this embodiment, the number of pleats of the bellows 7B is about four times the number of pleats of the bellows 7A having a short overall length.
The expansion / contraction length is also set to about 4 times.

2 and 3 are explanatory diagrams of the operation strokes of the movable energizing shafts 5A and 5B installed in the vacuum vessels 10A and 10B.
Shown in. Among them, FIG. 2 shows the opening time, and the opening operation of the movable energizing shafts 5A and 5B starts at the opening point A. Movable shaft 5A
Opens at high speed from the opening point A. Further, the movable shaft 5A terminates its operation at a position B in which each electrode is opened by about ⅕ of the total distance between the electrodes in the open state in each vacuum container, and stops in a steady state. On the other hand, the movable shaft 5B opens from the opening point A at a lower speed than the movable shaft 5A. Further, the movable shaft 5B ends its operation at the position C where about 4/5 of the total distance between the electrodes in the open state in each vacuum container is opened, and the movable shaft 5B stops in a steady state. When the electrodes are closed, the movable energizing shafts 5A and 5B are driven so that the closed pole D contacts the electrodes in the respective vacuum vessels at the same time. Since the movable energizing shaft 5A has a short operating distance and a high operating speed, its operating time is shorter than the operating time of the movable energizing shaft 5B. Therefore, the movable energizing shaft 5A is delayed by the difference between the respective operation times to start the operation.

In the above description, the case where the electrodes in the respective vacuum vessels operate at the same time has been described. However, when it is difficult to operate at the same time at the same time, a structure is adopted in which a slight simultaneous difference is provided as described below. You may. At the time of opening, the movable energizing shaft 5A is operated in advance, and the current is cut off at a high opening speed at the opening point. Further, when the electrodes are closed, the movable energizing shaft 5A is delayed so that
The electrodes on the side of the vacuum vessel 21B, where the movable energizing shaft moves slowly, are brought into contact with each other in advance, and the circuit is closed in the state where the closing speed is high.

According to this embodiment, the operating life of the bellows can be extended. That is, the operation of the bellows 7B for increasing the inter-electrode distance can be delayed. Therefore, the intervals between the pleats of the bellows 7B can be uniformly expanded and contracted substantially over the entire bellows, and the above-mentioned partial excessive expansion and contraction and the occurrence of waviness-like movements over the entire bellows can be suppressed. As a result, the operating life of the bellows 7B is
It becomes close to FIGS. 7 and 8. On the other hand, the bellows 7A moves at a high speed, but since the total number of folds is small, and the overall length is short and the mass is small, the above-mentioned undulation-like motion hardly occurs. Therefore, although the characteristics are lower than those of FIGS. 7 and 8, the rate of decrease is smaller than that of the bellows having a long operating distance, and the operating life can be extended.

On the other hand, when the current is cut off, the movable electrode 3A at the tip of the movable energizing shaft 5A to which the bellows 5A is connected is opened at high speed, so that there is no local concentration of the arc generated in the initial stage of opening and the electrode is damaged. Can be reduced and the blocking performance can be improved. Even when the electrodes are closed, the bellows 7
The movable electrode 3 at the tip of the movable energizing shaft 5A to which A is connected
Since A closes at a high speed, the pre-arc time is shortened, there is no local concentration of the arc generated between the electrodes due to this pre-arc, and damage to the electrodes can be reduced.

Next, a sectional view of the vacuum valve of the second invention is shown in FIG. The vacuum valve is composed of a single vacuum container 20 described later. Insulation cylinder that constitutes this vacuum container 20
11 is composed of an upper half short insulating cylinder 11A and a long insulating cylinder 11B concentrically joined to the insulating cylinder 11A via an annular partition plate 8 joined to the lower end of the insulating cylinder 11A.
Inside the vacuum container 20, movable electrodes 3A and 3B that can be brought into contact with and separated from the fixed electrodes 13A and 13B are arranged. The fixed electrodes 13A, 13B are fixed to an insulating cylinder 11 forming a vacuum container, and the movable electrodes 3A, 3B are movable energizing shafts 5A, 5B.
It is fixed to the tip of B. The movable energizing shafts 5A and 5B are
The movable flange 2A and the movable flange 2C, which is the same product as the movable flange 2A, are hermetically connected via the bellows 7A and 7B. When incorporated in a vacuum circuit breaker, the movable energizing shafts 5A, 5
B is driven by an operating mechanism (not shown).

The movable energizing shaft 5A uses a bellows 7A having a shorter operating distance than the bellows 7B joined to the movable energizing shaft 5B as in FIG. There is. On the other hand, a bellows 7B having a long expansion / contraction length and a long overall length is used for the movable energizing shaft 5B.
In this embodiment, the number of pleats of the bellows 7B is about 4 times the number of pleats of the bellows 7A having a short total length, and the expansion / contraction length is about 4 as well.
It is set to double. The operation of the movable energizing shafts 5A and 5B is similar to that of the movable energizing shafts 5A and 5B described in the first invention,
Since the effect is the same, the explanation is omitted.

Next, FIG. 5 shows a sectional view of the vacuum valve of the third invention. The vacuum valve is composed of a single vacuum container 21. Inside the vacuum container 21, a pair of movable electrodes 7 that can be contacted and separated
A and 7B are arranged. This movable electrode 7A, 7B
Is fixed to the tips of the movable energizing shafts 5A and 5B. The movable energizing shafts 5A and 5B are provided with a movable flange 2A and a movable flange 2C which is the same as the movable flange 2A via bellows 7A and 7B.
Is airtightly connected to. When the vacuum circuit breaker is incorporated, the movable energizing shafts 5A and 5B are driven by an operating mechanism (not shown).

Bellows 7A joined to the movable energizing shaft 5A
Uses a bellows 7A that has a shorter operating distance than the bellows 7B connected to the movable energization shaft 5B, that is, has fewer folds and a shorter overall length. The long bellows 7B is used. In this embodiment, the number of pleats of the bellows 7B is set to about four times and the expansion / contraction length is set to about four times the number of pleats of the bellows 5A having a short total length. The operation of the movable energizing shafts 5A and 5B is the same as that of the movable energizing shafts 5A and 5B described in the first aspect of the invention, and the effect thereof is also the same, and therefore the description thereof is omitted.

As described above, in the vacuum valve thus constructed, two bellows are used, and the movable energization shaft connected to one of the bellows is operated at high speed.
By operating the movable energization shaft connected to the other bellows at a low speed, it is possible to extend the switching life, and further,
It is possible to provide a vacuum valve having excellent shutoff performance.
This is because the function required when opening and closing the electrode can be divided into two parts, and each can have a different function.

As a first function, a wide interelectrode distance is required for a voltage having a high lightning impulse withstand voltage value in the electrode open state. For this function, the uneven movement of the bellows pleated pitch, which occurred when using a single bellows with a long operating distance and a large number of pleats,
This can be solved by slowing down the operating speed, and the switching life can be extended. However, when the opening / closing speed is reduced, the breaking performance also deteriorates. Therefore, in the above-described embodiment, the portion related to this breaking performance is assigned the second function, and the other bellows shares the function. In other words, by increasing the operating speed of the other bellows, the speed immediately after the electrodes are opened can be increased, local concentration of the arc generated between the electrodes can be suppressed, damage to the electrodes can be reduced, and breaking performance can be improved. You can Furthermore, since the bellows that operate at high speed have a small number of pleats and are used within a range where the operating distance is short, the expansion and contraction amount of each fold of the bellows can be made uniform even if the operating speed is increased, and the switching life cannot be shortened. Absent.

[0027]

As described above, according to the first aspect of the invention, there is provided a vacuum valve having a movable energizing shaft penetrating the bellows on one side of the vacuum container and a fixed energizing shaft penetrating the other side of the vacuum container. By connecting the fixed energizing shafts facing each other, the bellows of the vacuum valve on one side was penetrated to the bellows of the vacuum valve on one side by shortening the expansion and contraction length and reducing the number of folds with respect to the bellows of the vacuum valve on the other side. The movable shaft is operated at high speed to prevent the concentration of the arc immediately after the electrode is separated, the bellows of the vacuum valve on the other side is used to increase the withstand voltage value after opening, and the operation speed of the folds of this bellows is reduced to expand and contract due to waviness. Since the increase in the number of times is prevented, it is possible to obtain a vacuum valve having excellent withstand voltage characteristics and capable of extending the switching life.

According to the second invention, the bellows are provided on both sides of the vacuum container, the movable current-carrying shaft penetrating the bellows is provided, the fixed electrode is provided in the middle portion of the vacuum container, and the bellows on one side is attached to the bellows on the other side. On the other hand, by shortening the expansion and contraction length and reducing the number of pleats, the movable shaft penetrating one side of the bellows is operated at high speed to prevent the concentration of the arc immediately after the electrode is separated, and after the other side of the bellows is opened. In addition to increasing the withstand voltage value of 1, the increase in the number of times of expansion and contraction due to the swell of the folds of the bellows was prevented and the increase in the number of expansions and contractions was prevented.

According to the third aspect of the invention, the bellows are provided on both sides of the vacuum vessel, the movable energizing shafts are provided so as to penetrate the bellows, and the bellows on one side is shortened in expansion / contraction length with respect to the bellows on the other side. By reducing it, the movable shaft penetrating the bellows on one side is operated at high speed to prevent the concentration of the arc immediately after the electrode is opened, and the bellows on the other side increases the withstand voltage value after opening, and Since the increase in the number of times of expansion and contraction due to the undulation of the folds of the folds is prevented, it is possible to obtain a vacuum valve having excellent withstand voltage characteristics and capable of extending the switching life.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a vacuum valve of the first invention.

FIG. 2 is an oscilla fluff showing the operation of the vacuum valve of the first invention when the electrode is opened.

FIG. 3 is an oscillograph showing the operation of the vacuum valve of the first invention when the vacuum valve is closed.

FIG. 4 is a sectional view showing an embodiment of the vacuum valve of the second invention.

FIG. 5 is a sectional view showing an embodiment of the vacuum valve of the third invention.

FIG. 6 is a sectional view showing an example of a conventional vacuum valve.

FIG. 7 is a graph showing the relationship between the operating distance and the life of the bellows of the conventional vacuum valve.

FIG. 8 is a graph showing the relationship between the number of bellows and the life of a conventional vacuum valve.

[Explanation of symbols]

1A, 1B, 11, 11A, 11B ... Insulating cylinder, 2A, 2B,
2C, 2D ... end plates, 3A, 3B ... movable electrodes, 4A, 4
B, 13A, 13B ... fixed electrode, 5A, 5B ... movable energizing shaft,
6A, 6B ... Fixed energizing shaft, 7A, 7B ... Bellows, 10
A, 10B, 20, 21 ... Vacuum container.

Claims (3)

[Claims] 1. A vacuum valve having a movable energizing shaft penetrating a bellows on one side of a vacuum container and a fixed energizing shaft penetrating on the other side of the vacuum container is connected with the fixed energizing shaft facing each other. Then, a vacuum valve in which the bellows of the vacuum valve on one side is made shorter than the bellows of the vacuum valve on the other side so as to have a short expansion / contraction length and a small number of pleats. 2. A bellows is provided on both sides of the vacuum container, a movable current-carrying shaft penetrating the bellows is provided, a fixed electrode is provided at an intermediate portion of the vacuum container, and the bellows on one side is relative to the bellows on the other side. A vacuum valve with a short expansion and contraction length and a small number of pleats. 3. A bellows is provided on both sides of a vacuum container, a movable energizing shaft is provided so as to penetrate the bellows, and the bellows on one side of the bellows on the other side has a short expansion / contraction length and a small number of pleats. Vacuum valve.