JP2001126596A - Vacuum switch apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum switch which enhances a withstand voltage of an insulation lead surface in a vacuum and is permitted to achieve a small- dimension and ensure a reliability. SOLUTION: A vacuum switch of the invention performs a breaking, shutout and grounding opening and shutting in a vacuum comprising a bushing and a metal vessel. Since a differential stage capturing a soldering material on heating the brazing material is mounted on a surface of an electric conducting axis penetrating the bushing, the differential stage captures a dropping remainder on heat-binding of the brazing material and prevents a generation of a dropping mark on the surface of the electric conducting axis. Accordingly, the electric conducting axis having no rough parts caused by the dropping mark on the surface is obtainable, and a discharging of an electric field on the surface of the electric conducting axis is prevented. As a result, an irradiation of electron to an insulation surface of the busing, is decreased and a lead surface discharge voltage of the insulation lead surface is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is characterized in that a high voltage and a large current can be cut off, and that the disconnection and disconnection of the electric circuit and the grounding can be performed. The present invention relates to a structure of a vacuum switchgear, and more particularly to an invention of a structure for improving withstand voltage characteristics.

[0002]

2. Description of the Related Art As one of power receiving and distributing equipment, there is a vacuum switchgear capable of interrupting a high voltage and a large current and disconnecting and disconnecting an electric circuit, and performing disconnection, disconnection, and grounding in a vacuum. . Vacuum switchgear must have sufficient withstand voltage capability to safely energize, cut off, disconnect, and ground switching without causing dielectric breakdown such as ground fault discharge. That is, a ground fault discharge between the high-voltage charging unit and the ground potential unit, a discharge between the opened breaking contacts, and the like must be prevented from being caused by an external surge or a system AC voltage.

[0003] The withstand voltage performance of a vacuum switchgear is determined by the withstand voltage on the vacuum side surface of an insulator in a bushing for introducing a current from the outside into a vacuum while insulating a high voltage, and is also arranged in a vacuum. In addition, it depends on the creepage withstand voltage of the insulating rod which connects the breaking contact opening / closing operation mechanism (ground potential) and the breaking contact (high voltage charging unit) while insulating them. The reason why the withstand voltage of these vacuum creepage is important is that the withstand voltage of a vacuum gap where nothing exists between the electrodes and the creepage withstand voltage when a solid insulator such as ceramic is inserted between the electrodes, This is because the latter is lower even if the distance between them is the same.

Some prior arts for improving the withstand voltage characteristics of a vacuum creepage have already been proposed. As an example, FIG. 10 shows a conventional technique described in Japanese Patent Application Laid-Open No. 60-100324. In the figure, an insulating cylinder 21a forms a vacuum vessel and insulates a voltage applied to both ends thereof. The electrodes 24 and 25 are respectively energized shafts 24a and 25a
The energizing shafts 24a and 25a are respectively connected to end plates 22 and 23, respectively.
And the end plates 22, 23 are connected to an insulating cylinder 21a. The arc shield 29 is disposed to prevent spatter generated at the time of interruption between the electrodes from adhering to the insulating cylinder 21a. Shields 27 are provided on the end plates 22 and 23 for the same purpose. The electrode 25 is movable by the expansion and contraction of the bellows 26, and can open and close the contact.

With this configuration, the arc shield 2
Since the conductor 9 and the shield 27 are arranged so as to surround the conductor joints at both ends of the insulating cylinder 21a, the electric field at the conductor joint, that is, the electric field at the so-called triple junction, is reduced. For this reason, the withstand voltage characteristics along the surface of the insulating cylinder 1a increase.

FIG. 11 shows a cross section of a vacuum valve described as an embodiment in the above-mentioned Japanese Patent Application Laid-Open No. 60-100324. As shown in the figure, a metal film or a semiconductive film 31a is applied to the vacuum side surface of the insulating cylinder 21a and the surface near the end of the arc shield 29. Further, the end plate 22,
23 has a cylindrical outer shield 30 having the same potential as that of the insulating cylinder 21.
a, 21b are installed so as to cover about half.

In this configuration, by arranging the arc shield 29, the cylindrical outer shield 30, and the coating 31a at the positions shown in FIG. 1, the equipotential distribution on the vacuum side surface of the insulating cylinder 21a becomes nearly uniform. As a result, the creeping pressure resistance is improved. Further, the film 31a does not emit as much secondary electrons as alumina ceramics against the collision of field emission electrons emitted from the tip of the arc shield 29. It contributes to improvement.

[0008]

Although the prior art of improving the creepage withstand voltage of vacuum insulators such as alumina ceramics has been proposed as described above, both of the above examples are directed to vacuum valves. I have. Therefore, even if the technology of the vacuum valve is applied as it is to a vacuum switching device having a structure different from that of the vacuum valve, the following problems occur.

First, the difference between the structures of the vacuum valve and the vacuum switching device will be described. As described above, two portions of the insulator that are exposed to the vacuum in the vacuum switchgear include the inner surface of the insulator of the bushing and the surface of the insulating rod.
When the structure is described from the bushing, a cylindrical insulator is used as a constituent member, and a shield 27 in FIG. 10 of the prior art is similarly attached to both ends of the insulator to reduce a triple junction electric field at both ends of the insulator. ing. The energizing shaft passes through the end plate as shown in FIG.

The structure of the bushing thus appears to be relatively similar to that of the vacuum valve, with the following differences. The distance between the surface of the current-carrying shaft and the inner surface of the cylindrical insulator increases to some extent in the case of a vacuum valve due to the restriction of the contact diameter. On the other hand, in a vacuum switching device, it is not always necessary to arrange the contacts in the cylindrical insulator, so a small-diameter cylindrical insulator may be used. In this case, the distance is shorter than that of the vacuum valve.

The difference in the phenomena caused by the difference in the distance is as follows. In the case of a vacuum valve, the electric field on the surface of the conducting shaft caused by the potential difference between the arc shield 29 and the conducting shafts 24a and 25a in FIG. 10 is small. However, in a vacuum switchgear, the electric field becomes large, and if the electric field is very large and the polarity is negative, the electric field is emitted from the surface of the conducting shaft. Some of the emitted electrons are irradiated to the surface of the insulator, and secondary electrons are emitted from the surface of the insulator. The irradiated surface that has lost electrons due to secondary electron emission is positively charged, distorting and enhancing the surrounding electric field. As a result, in spite of a voltage that is not so high, a large electric field is locally generated, leading to creeping discharge.

The phenomenon from the generation of the secondary electron emission to the discharge is no different from the general creeping discharge phenomenon, and is the same as that of the vacuum bulb. However, the primary electron supply source for causing secondary electron emission in a general surface discharge including the surface of a vacuum valve is only a portion in contact with the conductor at both ends of the insulator, that is, a triple junction. However, in the case of the bushing in the vacuum switching device, primary electrons are supplied not only from the triple junction but also from the surface of the energized shaft. This point is a phenomenon different from the vacuum valve, and for this reason, the withstand voltage characteristic becomes worse than that of the vacuum valve.

As a factor that further deteriorates the withstand voltage characteristics, an electrode such as an energized shaft of a bushing and a breaking contact or a brazing material used for joining the energized shaft and the end plate of the bushing is dripped onto the surface of the energized shaft at the time of heating and joining, and a trace of the trace is formed. May remain on the surface. That is, most of the brazing material liquefied by heating remains on the joining surface and contributes to joining, but a part thereof becomes excess brazing material and drops on the surface of the current-carrying shaft by gravity. If the amount of brazing material is reduced in advance, the amount of dripping will decrease, but a certain amount of brazing is required to obtain sufficient bonding strength, and surplus dripping cannot be avoided. The brazing filler metal remains on the surface of the current-carrying shaft where the brazing filler metal has been dropped, and bulges only at that portion to form irregularities. Since the unevenness increases the electric field on the surface of the current-carrying shaft and promotes the emission of field electrons, there is a problem that electron irradiation to the insulator of the bushing is activated, and the withstand voltage is further reduced.

As a countermeasure to the above, there is a method of increasing the distance between the surface of the current-carrying shaft and the inner surface of the insulating cylinder. However, this is nothing less than an increase in the size, and in order to improve the withstand voltage while keeping the size as small as possible. I have to suggest another way. One such method is disclosed in JP-A-60-100.
Although there is a method of improving the creepage withstand voltage by applying a metal film or a semiconductive film on the surface of the insulator as in the embodiment of Japanese Patent No. 324, the structure around the insulator is different from the vacuum valve as described above. Because of the differences, the application area must be proposed again.

On the other hand, although the insulating rod is not provided in the vacuum valve, as a conventional technique for improving the withstand voltage, an electric field relaxation shield is generally mounted at both ends of the insulator. However, the rod length is increased to some extent in order to obtain a sufficient creepage withstand voltage by using only the electric field relaxation shield, and there has been a problem that the size of the entire device is increased due to this effect.

The present invention has been made in view of such circumstances, and has been made to improve the withstand voltage on the surface of an insulator in a vacuum,
It is an object of the present invention to provide a vacuum switchgear capable of realizing miniaturization and ensuring reliability.

[0017]

SUMMARY OF THE INVENTION A vacuum switchgear according to the present invention is a vacuum switchgear for shutting off, disconnecting and opening and closing a ground in a vacuum container comprising a bushing and a metal container. Is provided with a step on the surface of the brazing material to catch the brazing material when the brazing material is heated.

Further, in a vacuum opening / closing device in which disconnection, disconnection, and ground opening / closing are performed in a vacuum container comprising a bushing and a metal container, the brazing material is heated when the brazing material is heated on the surface of an energizing shaft passing through the bushing. It is provided with a catching groove or overhang.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. Embodiment 1 FIG. A vacuum switching device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a vacuum switching device according to the first embodiment. The configuration of the vacuum switching device according to the present embodiment will be described with reference to FIG.

Various components are arranged in a vacuum container constituted by the metal container 1 and the bushing 4. That is, the current-carrying shaft 3 connected to the bushing 4 on the left side in FIG.
A circuit breaker / disconnector 2 composed of a movable electrode 2a, a fixed electrode 2b, an arc shield 2c, and a shield support insulating cylinder 2d is arranged at one end of b. An energizing shaft 3a is connected to the movable electrode 2a, and an insulating rod 5 composed of an insulating rod 5a, a ground-side electric field shield 5b, and a high-voltage electric field shield 5c is arranged at the other end. An operation rod 8c is connected to the insulating rod 5 on the ground-side electric field shield 5b side, and a bellows 8a and a guide 8b are combined with the operation rod 8c to form an operation mechanism unit 8. A shunt 7 composed of a flexible conductor 7a and a conductor holder 7b is joined to the middle of the conducting shaft 3a, and a conducting shaft 3c is joined to the other end of the shunt 7. A bushing 4 on the right side in the figure is disposed at one end of the conducting shaft 3c, and a high-voltage side electrode 6b is disposed at the other end.
The high voltage side electrode 6b and the ground side electrode 6a constitute a grounding switch 6. The operating mechanism 8 is connected to the ground electrode 6a.
An operation mechanism 8 similar to the above is connected.

The bushing 4 on the right side in the figure is an insulating cylinder 4a,
It has a container-side electric field shield 4b, an end plate-side electric field shield 4c, and an end plate 4d, and an energizing shaft 3b is disposed through the end plate 4d. On the other hand, since the shield supporting insulator 2d is arranged near the bushing 4 on the left side in the drawing,
In the bushing 4 on the left side, a container-side electric field shield 4e that can simultaneously reduce the electric field at the end of the shield support insulator 2d and the insulating cylinder 4a is arranged.

Although not shown, the two bushings 4
Cable busbars from the outside are connected to the ends of the current-carrying shafts 3b and 3c that protrude outwardly. Although not shown, a drive mechanism is connected to the outside of the operating mechanism 8 to open and close the circuit breaker / disconnector 2 and the grounding switch 6. The set of devices shown in FIG. 1 is housed in a power distribution panel together with the drive mechanism and cables, an instrument transformer, an instrument transformer, instruments, and the like, and functions as power receiving and distribution equipment. The pressure inside the vacuum vessel is about 10 ^-6 Torr.

As described above, in the vacuum switching device, a circuit breaker, a disconnecting switch, and a grounding switch are provided in a vacuum vessel. here,
In the present embodiment, the circuit breaker / disconnector 2 is used because the cutoff and disconnection are performed by a pair of electrodes. The locations of the individual members inside the vacuum vessel such as the circuit breaker / disconnector 2, the grounding switch 6, the insulating rod 5, and the shunt 7 do not necessarily have to be as shown in FIG. Even so, the same function can be obtained.

FIG. 1 shows ranges A and B surrounded by dotted lines, which will be used in the description of FIG.

Here, a method of joining the individual members will be described. Each member is assembled at a predetermined joint position, and a solid brazing material having a suitable shape is inserted into each joint surface. The brazing material is mainly composed of silver and copper, and has a melting point of 500 ° C.
To about 800 ° C. depending on the type. Next, the whole assembled member is placed in a furnace and heated to a temperature equal to or higher than the melting point to liquefy the brazing material. The brazing material penetrates widely and uniformly into the joint surface by the capillary phenomenon. After a while, the brazing material is cooled and the brazing material is solidified to complete the joining. The use of the brazing material has an advantage that gas permeation from the outside can be suppressed as compared with other joining methods.

Next, the features and functions of this embodiment will be described. FIG. 2 is an enlarged view of only a portion indicated by a dotted line A in FIG. As shown in FIG. 2, the energizing shaft 3c is provided with a step 9 at a position near the position intersecting the end plate 4d, and the diameter of the shaft changes at the step. Although the direction of gravity is shown in the figure, the diameter is larger on the lower side in the direction of gravity.
This is a feature of the present embodiment.

In order to explain the function of the step 9, the state of the conducting shaft 3c from heating to cooling of the brazing material will be described.
As described above, a brazing material is used for joining the energized shaft 3c and the end plate 4d. To explain in more detail, when gravity acts in the direction of the arrow shown in FIG. 2, the inner diameter is smaller than the diameter of the energized shaft 3c. A slightly larger ring-shaped brazing material is placed on the surface of the end plate 4d so as to pass the conducting shaft 3c. When heated in this state, the liquefied brazing material permeates the joint surface by capillary action. However, since there is a limit to the amount of brazing material that can remain on the joint surface, the surplus is dropped along the current-carrying shaft 3c by gravity. The step 9 catches this surplus brazing material when it drip. Since the liquefied brazing material has a certain surface tension, if the size of the step is appropriate, the liquefied brazing material captured at the step does not overflow.

The effect of the step 9 is as follows. If the liquefied brazing material is cooled and solidified while being trapped by the steps, a clean current-carrying shaft surface can be obtained in a portion lower than the steps 9. As a result, even if a large negative electric field is generated on the surface of the current-carrying shaft, the amount of electron emission due to field emission can be reduced as compared with the case where unevenness due to the brazing material dripping exists. Accordingly, secondary electron emission on the surface of the insulating cylinder 4a is suppressed by the amount of electron irradiation to the insulating cylinder 4a, and the insulating cylinder 4a
The amount of distortion of the electric field distribution on the surface also decreases. As a result, the creepage withstand voltage is improved.

Here, when the direction of gravity in FIG. 2 is opposite to the arrow in the figure, the brazing filler metal used for the connection of the other end of the conducting shaft 3c is dropped, so the step 9 at the position shown in the figure is installed. It has no effect. In this case, it is necessary to provide a similar step on the other end side of the conduction shaft 3c. Generally, brazing material is used at both ends of the current-carrying shaft, so it is necessary to provide a step at both ends. In the bushing 4 on the left side of FIG. 1, the same effect can be obtained by providing the step at the same position. Further, in FIG. 2, the diameter before and after the step is constant, but the same effect can be obtained even if the diameter changes in a taper shape.

In order to confirm the effect of increasing the creeping pressure of the bushing by the above-described structure, the creeping pressure inside the insulating cylinder of the bushing in which a dripping trace of the brazing material is not left on the surface of the current-carrying shaft by a structure similar to the above is shown in FIG. Shown in In the figure,
Sample No. 1 to 4 show an electric field shield on the vacuum vessel side (see FIG.
4b) is a result of applying a negative high voltage to the conducting shaft. These results vary, but are at most about 85 kV. On the other hand, sample N
o. Nos. 5 to 7 are the results of applying the same voltage to the sample in which no trace of the brazing filler metal was left on the surface of the conducting shaft. Creepage breakdown voltage of 130k for all three samples
It has risen to about V. Thus, the effect has been confirmed by experiments.

Embodiment 2 Second Embodiment A vacuum switching device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a longitudinal sectional view showing a main part of a vacuum switchgear according to the second embodiment.
FIG. 2 is an enlarged view corresponding to a range indicated by a dotted line A in FIG. 1. This embodiment is the same as the first embodiment except for the structure of the main part.

The features of this embodiment will be described with reference to FIG.
The groove 10 is provided at a position near the position where the current-carrying shaft 3c intersects with the end plate 4d. The diameter of the conducting shaft 3c does not change above and below the groove 10.

The function of the groove 10 is to capture excess brazing material dropped by gravity. Since the liquefied brazing material has a certain surface tension, the captured liquefied brazing material does not overflow if the width and depth of the groove are appropriate.
As a result, the same effect as in the first embodiment can be obtained.

Embodiment 3 Third Embodiment A vacuum switching device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a longitudinal sectional view showing a main part of a vacuum switchgear according to the third embodiment.
FIG. 2 is an enlarged view corresponding to a range indicated by a dotted line A in FIG. 1. This embodiment is the same as the first embodiment except for the structure of the main part.

The features of this embodiment will be described with reference to FIG.
A brazing filler metal trap 11 having a shape projecting from the energizing shaft 3c is provided at a position near the position where the energizing shaft 3c intersects with the end plate 4d. The brazing filler metal trap 11
It is positioned and attached to a predetermined position by a desired method. At this time, it is only necessary to attach the wrap 11 without preparing any brazing material.

The function of the brazing material trap 11 is to capture excess brazing material dropped by gravity, as in the first and second embodiments. Since the liquefied brazing material has a certain surface tension, the captured liquefied brazing material does not overflow if the shape of the brazing material trap 11 is appropriate. As a result, the same effect as in the first embodiment can be obtained. In addition, the brazing material trap 1 is formed by the dripped brazing material itself.
1 and the conducting shaft 3c are joined.

Embodiment 4 FIG. Embodiment 4 A vacuum switching device according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 6 is a longitudinal sectional view showing a main part of a vacuum switchgear according to a fourth embodiment.
FIG. 2 is an enlarged view corresponding to a range indicated by a dotted line A in FIG. 1. This embodiment is the same as the first embodiment except for the structure of the main part.

The features of this embodiment will be described with reference to FIG.
Container-side electric field shield 4 on the inner surface of insulating cylinder 4a
b, the part 1 not hidden behind the end plate side electric field shield 4c
Chromium oxide (Cr) which is a secondary electron emission suppressing material
₂ O ₃ ) is applied. Copper oxide (Cu ₂ O) may be applied instead of chromium oxide. Here, the steps, grooves, and overhangs described in the first to third embodiments are not particularly provided on the energizing shaft 3c. The insulating cylinder 4a is formed using alumina except for the portion 12 on which the secondary electron emission suppressing material is applied.

To explain the function of these secondary electron emission suppressing materials, FIG. 7 shows the relationship between the secondary electron emission coefficient and the incident electron (primary electron) energy in chromium oxide, copper oxide, and alumina (Al ₂ O ₃ ). Show characteristics. The secondary electron emission coefficient is a ratio between the number of incident electrons and the number of secondary electrons. The larger this coefficient is, the more active the secondary electrons are emitted. As shown in FIG. 7, the secondary electron emission coefficient of alumina used for the insulating tube 4a reaches a maximum of 6.4, whereas chromium oxide is at most 1 or less and copper oxide slightly exceeds 1. Therefore, secondary electron emission is not so active as compared with alumina, and therefore, when a coating of chromium oxide or copper oxide is applied to the alumina surface, secondary electron emission is suppressed. As a result,
Secondary electron emission can further prevent a secondary electron emission avalanche that causes subsequent secondary electron emission and causes electron number multiplication.

The volume resistivity of alumina is 10 ¹⁵ Ωc.
m, whereas that of chromium oxide or copper oxide is 1
It is about four digits lower, about 0 ¹¹ Ωcm. Here, the surface from which the secondary electrons have been emitted is deficient in electrons, so that the surface is positively charged and has a potential. However, the time required for the positively charged portion to return to the original potential is shorter when the volume resistivity is smaller. Therefore, even if chromium oxide or copper oxide is positively charged, it can return to the original potential in a shorter time than alumina. For this reason, the distortion of the electric field on the insulator surface is also extremely small.

For the above reasons, when the surface of the insulator is coated with the secondary electron emission suppressing material, the creeping surface voltage is improved.
Here, in the present embodiment, the range of the coating is limited, for the following reason. As described above, the volume resistivity of chromium oxide or copper oxide is about 10 ¹¹ Ωcm, which is a relatively low value as the resistance of the insulator.
For this reason, when these are coated on the entire surface of the insulator, the value of the insulation resistance decreases, and the function as the insulator may not be maintained. Therefore, it is necessary to leave a region where the insulator is exposed without coating and to prevent a decrease in insulation resistance.

Therefore, in the present embodiment, the coating is not applied to the portion where the secondary electron emission does not occur much. In other words, the range where the collision of the electrons emitted from the electric field shield is active or the range where the secondary electrons become the primary electrons and the secondary electron emission avalanche is not hidden behind the electric field shield at both ends, Only the area is coated, the rest of the area exposes the insulation. By limiting the coating range in this manner, the creepage withstand voltage can be increased while maintaining the insulation resistance at a favorable value.

Embodiment 5 FIG. Embodiment 5 A vacuum switching device according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 8 is a longitudinal sectional view showing a main part of a vacuum switchgear according to the fifth embodiment.
FIG. 2 is an enlarged view corresponding to a range of a dotted line B in FIG. 1. This embodiment is the same as the first embodiment except for the structure of the main part.

The features of this embodiment will be described with reference to FIG.
Chromium oxide (Cr ₂ O ₃ ), which is a secondary electron emission suppressing material, is applied to portions 13 of the surface of the insulating rod 5a that are not hidden behind the electric field shields 5b and 5c at both ends of the insulating rod 5a. Copper oxide (Cu ₂ O) may be applied instead of chromium oxide.

The insulating rod having the above features has the same functions and effects as the fourth embodiment. That is, it has a function of suppressing the avalanche of secondary electron emission by coating the insulator with a material having a small secondary electron emission coefficient. This has the effect of increasing the surface withstand voltage of the insulating rod. Also, by not coating the portion of the insulator surface behind the electric field shield, the insulation resistance of the insulating rod is reduced to a minimum, and there is an effect of preventing an increase in leakage current. As the withstand voltage further increases,
By shortening the length of the insulating rod, the size of the device can be reduced.

Embodiment 6 FIG. Embodiment 6 A vacuum switching device according to Embodiment 6 of the present invention will be described with reference to FIGS. 1, 6, and 8. FIG.
In this embodiment, the two bushings 4 in the vacuum switchgear shown in FIG. 1 are coated with a secondary electron emission suppressing material on the portions shown in FIG. 5 to improve the creeping withstand voltage. On the other hand, the insulating rod 5 is also coated with a secondary electron emission suppressing material on the portion shown in FIG. Chromium oxide or copper oxide is used as the secondary electron emission suppressing material.

As described above, by coating the entire surface of the vacuum insulator existing inside the vacuum vessel of the vacuum switchgear with the secondary electron emission suppressing material, the withstand voltage characteristics of the entire vacuum switchgear can be improved.

Embodiment 7 FIG. Embodiment 7 A vacuum switching apparatus according to Embodiment 7 of the present invention will be described with reference to FIG. FIG. 9 is a longitudinal sectional view showing a main part of the vacuum switching device according to the present embodiment.
FIG. 4 is an enlarged view corresponding to the range of a dotted line A. This embodiment is the same as the first embodiment except for the structure of the main part.

As shown in FIG. 9, chromium oxide (Cr), which is a secondary electron emission suppressing material, is provided on the inner surface of the insulating cylinder 4a, which is not hidden behind the container-side electric field shield 4b and the end plate-side electric field shield 4c. ₂ O ₃ ) or copper oxide (Cu ₂ O). In addition, step 9 described in the first embodiment is provided on energizing shaft 3c.

By applying the secondary electron emission suppressing material in a specified range, the creeping withstand voltage can be improved while preventing the insulation resistance of the bushing 4 from lowering. Further, even if the surplus amount of the brazing material used for joining the end plate 4d and the energizing shaft 3c during heating drops along the energizing shaft 3c in the direction of gravity, the step 9
And the area below the step 9 can be kept clean. This step 9 causes the energized shaft 3
The amount of electrons emitted from the surface c can be suppressed, and the number of primary electrons irradiated on the surface of the insulating cylinder 4a can be reduced.

As described above, when the secondary electron emission avalanche is suppressed by the coating of the secondary electron emission suppressing material and the number of electrons radiated from the conducting shaft 3c is reduced by the step 9, the insulating cylinder 4
The surface withstand voltage of “a” is greatly improved.

Here, in FIG. 9, the step 9 is provided on the energizing shaft 3c, but the same effect can be obtained by providing the groove 10 shown in FIG. 3 or the brazing material trap 11 shown in FIG. .

Embodiment 8 FIG. Embodiment 8 A vacuum switching apparatus according to Embodiment 8 of the present invention will be described with reference to FIGS.
In the present embodiment, the two bushings 4 in the vacuum switchgear of FIG. 1 are coated with a secondary electron emission suppressing material at the portions shown in FIG. Here, instead of the step 9, the groove 10 shown in FIG. 4 or the brazing material trap 11 shown in FIG. 5 may be provided. If the secondary electron emission avalanche is suppressed by coating the secondary electron emission suppressing material, and the number of electrons emitted from the conducting shaft 3c is reduced by the step 9, the surface breakdown voltage of the insulating cylinder 4a is greatly improved. On the other hand, the insulating rod 5 is also coated with a secondary electron emission suppressing material on the portion shown in FIG. As the secondary electron emission suppressing material, chromium oxide or copper oxide is used for both the bushing 4 and the insulating rod 5.

By simultaneously taking measures to improve the withstand voltage of the bushing 4 and the insulating rod 5, there is an effect of improving the withstand voltage characteristics of the entire vacuum switchgear.

[0055]

The vacuum switchgear according to the present invention is a vacuum switchgear which performs shut-off, disconnection, and ground opening and closing in a vacuum container comprising a bushing and a metal container. Since a step for trapping the brazing material is provided when the brazing material is heated, a surplus of dripping during the heating and joining of the brazing material is trapped at the step to prevent the formation of dripping marks on the surface of the conducting shaft. Therefore, a current-carrying shaft having no irregularities due to dripping marks on the surface can be obtained, and field emission from the surface of the current-carrying shaft can be suppressed. As a result, the amount of electron irradiation on the insulator surface of the bushing decreases, and the creeping discharge voltage of the insulator increases.

Further, in a vacuum opening / closing device in which shut-off, disconnection, and ground opening / closing are performed in a vacuum container including a bushing and a metal container, the brazing material is heated when the brazing material is heated. Since the groove or the overhanging portion is provided, the surplus of the dripping at the time of the heating and joining of the brazing material is captured at the groove or the overhanging portion, thereby preventing the formation of the drip mark on the surface of the current-carrying shaft. Therefore, a current-carrying shaft having no irregularities due to dripping marks on the surface can be obtained, and field emission from the surface of the current-carrying shaft can be suppressed. As a result, the amount of electron irradiation on the insulator surface of the bushing decreases, and the creeping discharge voltage of the insulator increases.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a vacuum switching device according to a first embodiment.

FIG. 2 is an enlarged view of a main part relating to the first embodiment, in a dotted line range A of the vacuum switchgear of FIG. 1;

FIG. 3 is a diagram for explaining an effect of the vacuum switching device of the first embodiment.

FIG. 4 is an enlarged view of a main part according to a second embodiment.

FIG. 5 is an enlarged view of a main part according to the third embodiment.

FIG. 6 is an enlarged view of a main part according to a fourth embodiment.

FIG. 7 is a view for explaining functions and effects of the vacuum switching device of FIG. 6;

FIG. 8 is an enlarged view of a main part according to a fifth embodiment.

FIG. 9 is an enlarged view of a main part according to the seventh embodiment.

FIG. 10 is a longitudinal sectional view of a conventional vacuum valve.

FIG. 11 is a longitudinal sectional view of a conventional vacuum valve.

[Explanation of symbols]

Reference Signs List 1 metal container, 2 circuit breaker / disconnector, 2a movable electrode, 2b fixed electrode, 2c arc shield, 2d
Shield supporting insulating cylinder, 3a, 3b, 3c conducting shaft,
Reference Signs List 4 bushing, 4a insulating cylinder, 4b, 4e container side electric field shield, 4c end plate side electric field shield, 4d end plate, 5 insulating rod, 5a insulating rod, 5b ground side electric field shield, 5c high voltage side electric field shield, 6 ground switch 6a ground electrode, 6b high voltage electrode, 7
Shunt, 7a flexible conductor, 7b conductor holder, 8 operation mechanism, 8a bellows, 8b guide, 8c operation rod, 9 steps, 10 groove, 11
Brazing material trap, 21a insulating cylinder, 22, 23 end plate, 24, 25 electrode, 24a, 25a conducting shaft,
26 Bellows, 27 shield, 29 arc shield, 30 cylindrical outer shield, 31a coating.

Claims (2)

[Claims] 1. A vacuum opening / closing device for shutting off, disconnecting, and opening and closing a ground in a vacuum vessel comprising a bushing and a metal container, wherein the brazing material is heated on the surface of an energizing shaft passing through the bushing when the brazing material is heated. A vacuum switchgear characterized by having a step for catching. 2. A vacuum opening / closing device in which shutoff, disconnection, and ground opening / closing are performed in a vacuum container including a bushing and a metal container, wherein the brazing material is heated on a surface of a current-carrying shaft passing through the bushing when the brazing material is heated. A vacuum opening / closing device comprising a groove or an overhanging portion for capturing.