JP2024126422A - Vacuum valve - Google Patents

Abstract

To prevent the generation of a partial discharge in an internal part of a gap by suppressing an increase of a magnetic field of the internal part of the gap at the time of application of a voltage in the case where the gap occurs when applying an insulation resin.SOLUTION: A vacuum valve comprises: a vacuum container 1 that is constructed by assembling metal members (2, 3, 5, 6, and 7) and insulation members (1a and 1b) so as to house electrodes E1 and E2 so as to enable a separation and a contact; an insulation resin 12 that is applied and molded so as to cover the vacuum container; magnetic field relaxation means that is added to the insulation resin, includes an electrophoresis property, and includes a function for suppressing an increase of an electric field; and moving approach means of moving and approaching the electric field relaxation means toward each gap in the case where gaps Ag1 and Ag2 are generated along a part where a stress is easily concentrated from the insulation resin and a boundary surface of each metal member and insulation member when adding the insulation resin. In the state where the electric field relaxation means is approached to each gap, the generation of a partial discharge in an internal part of each gap is prevented by suppressing an increase of an electric field in the internal part of each gap at the time of an application of a voltage.SELECTED DRAWING: Figure 3

Description

An embodiment of the present invention relates to a vacuum valve.

Switchgear equipped with switches such as circuit breakers and disconnectors is known as a switching device for receiving and distributing electricity installed in buildings and large facilities. A vacuum valve is used as a component of the switchgear. The inside of the vacuum valve is maintained in a constant insulating state by a vacuum container (also called an insulating container). A pair of electrodes are housed inside this vacuum container so that they can be connected and disconnected. In this case, by connecting and disconnecting the pair of electrodes, fault currents are interrupted and load currents are opened and closed, and power is supplied stably from the switchgear.

JP 2020-198278 A JP 2021-174587 A

The above-mentioned vacuum valve includes a type (e.g., a molded vacuum valve) that is molded by adding insulating resin to cover the vacuum vessel. In a molded vacuum valve, the vacuum vessel has a composite cylindrical shape with an insulating porcelain tube connected to both ends of an arc shield arranged to surround a pair of electrodes, and is equipped with an external shield that extends from both ends of this composite cylindrical vacuum vessel to partially surround the insulating porcelain tube without contacting the insulating porcelain tube.

The arc shield is a metal member made of a metal (conductive) material whose main components are, for example, copper or stainless steel. The insulating porcelain tube is an insulating member made of an insulating material such as alumina ceramic. The outer shield is a metal member made of a metal (conductive) material such as, for example, copper, aluminum, stainless steel, etc.

Here, when the insulating resin is applied to cover the vacuum vessel, it is preferable that the insulating resin is in close contact with the above-mentioned metal members (i.e., arc shield, external shield) and insulating members (i.e., insulating porcelain tube) without any gaps.

However, the three components mentioned above (i.e., insulating resin, metal member, and insulating member) have different linear expansion coefficients (also called thermal expansion coefficients). For this reason, if we assume that the length and volume of these three components increase or decrease due to a change in temperature, the rates at which the length and volume of each of the three components increase or decrease will also differ from one another due to the different linear expansion coefficients (thermal expansion coefficients).

In this case, depending on the degree of the different rates of increase and decrease, localized internal stress may occur, and depending on the magnitude of the internal stress, localized peeling may occur between the insulating resin and the metal member and insulating member. In particular, in insulating resins that use thermosetting resins, sink marks may occur due to thermal curing.

In either case, voids (also called air pockets or gaps) where no insulating resin is present may occur along the interface between the insulating resin and the metal member and/or the interface between the insulating resin and the insulating member.

In this case, if the molded vacuum valve is operated (i.e., voltage is applied) while a gap has occurred, the electric field inside the gap rises, and a high electric field (i.e., a state in which the electric field strength is high) is generated inside the gap. When the height of the electric field exceeds the air's partial discharge generating electric field, a partial discharge occurs inside the gap, and if this partial discharge causes, for example, the decomposition and deterioration of the insulating resin progresses, it cannot be denied that it can lead to a ground fault.

The object of the present invention is to provide a molded vacuum valve that, when a gap is generated when insulating resin is added, prevents the occurrence of partial discharges in the gap by suppressing the increase in the electric field in the gap when voltage is applied.

According to an embodiment, the device includes a vacuum container formed by combining a metal member and an insulating member so as to accommodate a pair of electrodes in a releasable manner, an insulating resin molded by adding it to cover the vacuum container, an electric field mitigation means added to the insulating resin, which has electrophoretic properties and has a function of suppressing an increase in the electric field, and a moving proximity means for moving the electric field mitigation means toward the gap and bringing it close to the gap when a gap where no insulating resin is present occurs along a portion of the interface between the insulating resin and the metal member and/or the interface between the insulating resin and the insulating member where stress is likely to concentrate when the insulating resin is added to cover the vacuum container. When the electric field mitigation means is brought close to the gap, the electric field inside the gap is prevented from increasing when a voltage is applied, thereby preventing the occurrence of partial discharge inside the gap.

FIG. 2 is a cross-sectional view of a molded vacuum valve according to an embodiment. FIG. 4 is a partial cross-sectional view showing a state in which a void has occurred in a portion where stress is likely to concentrate. FIG. 2 is a cross-sectional view showing a state in which an electric field relaxation filler is placed in close proximity along the entire surface of a gap. FIG. 4 is a cross-sectional view showing a state in which an electric field relaxation filler is placed close to a triple junction of a void. FIG. 4 is a cross-sectional view showing a state in which an electric field relaxation filler is added to an insulating resin. FIG. 11 is a graph comparing the intensity of the electric field generated in a gap depending on whether or not an electric field relaxation filler is used.

"One embodiment"
Fig. 1 is a diagram showing the basic structure of a vacuum valve P according to this embodiment. The vacuum valve P comprises a fixed electrode E1, a movable electrode E2, a vacuum vessel 1 (also called an insulating vessel), a fixed sealing metal fitting 2, a movable sealing metal fitting 3, an airtightness maintaining mechanism 4, an arc shield 5, a fixed outer shield 6, and a movable outer shield 7. In the example of Fig. 1, the fixed electrode E1, the movable electrode E2, and the airtightness maintaining mechanism 4 are housed in the vacuum vessel 1.

As shown in FIG. 1, the vacuum vessel 1 has a hollow cylindrical shape centered on an imaginary axis Px that defines the center of the vacuum valve P. When viewed in the direction of the imaginary axis Px (in other words, the direction in which electrodes E1 and E2, described below, come into contact with each other), the vacuum vessel 1 is open at both ends. Both openings (fixed side opening K1, movable side opening K2) are covered by the fixed side sealing metal fitting 2 and the movable side sealing metal fitting 3. That is, the fixed side opening K1 is closed by the fixed side sealing member 2, and the movable side opening K2 is closed by the movable side sealing metal fitting 3.

The vacuum vessel 1 is configured by connecting insulating porcelain tubes (fixed insulating porcelain tube 1a, movable insulating porcelain tube 1b) to both ends (one end T1, the other end T2) of the arc shield 5 in the direction of the imaginary axis Px (the direction in which the electrodes E1, E2 move together). That is, the fixed insulating porcelain tube 1a is connected to one end T1 of the arc shield 5, and the movable insulating porcelain tube 1b is connected to the other end T2 of the arc shield 5.

The insulating porcelain tubes 1a, 1b are configured to have the same thickness. The arc shield 5 is configured to be thinner than the insulating porcelain tubes 1a, 1b. The insulating porcelain tubes 1a, 1b and the arc shield 5 are hollow cylindrical with the center at the imaginary axis Px, and the respective radial dimensions (radius, diameter) are set to be approximately the same. As a result, the insulating porcelain tubes 1a, 1b and the arc shield 5 interposed between the insulating porcelain tubes 1a, 1b are arranged in a straight line next to each other while extending along the imaginary axis Px.

In this state, the arc shield 5 is arranged to surround the pair of electrodes E1, E2, specifically, to accommodate within its interior (inner side) the fixed contact 8 of the fixed electrode E1 and the movable contact 10 of the movable electrode E2, which will be described later.

In this case, the fixed sealing metal fitting 2 and the movable sealing metal fitting 3 are metal members made of a metal (conductive) material whose main component is, for example, stainless steel. The insulating porcelain tubes 1a and 1b are insulating members made of an insulating material such as alumina ceramic. The arc shield 5 is a metal member made of a metal (conductive) material whose main component is, for example, copper or stainless steel.

The fixed electrode E1 and the movable electrode E2 are arranged concentrically around the imaginary axis Px and extend in alignment along the imaginary axis Px. The fixed electrode E1 has a fixed contact 8 and a fixed current-carrying shaft 9. The movable electrode E2 has a movable contact 10 and a movable current-carrying shaft 11. The fixed current-carrying shaft 9 and the movable current-carrying shaft 11 are cylindrical and have the same diameter, and are made of a material with high electrical conductivity (e.g., copper (Cu), copper alloy, silver (Ag)).

The fixed contact 8 and the movable contact 10 have the same contour size and are arranged opposite each other. The fixed contact 8 is connected to one end of the fixed current-carrying shaft 9, the other end of which is fixed to the vacuum valve P immovably along the imaginary axis Px via the fixed side sealing metal fitting 2. The movable contact 10 is connected to one end of the movable current-carrying shaft 11, the other end of which is connected to an operating mechanism (not shown) via the movable side sealing metal fitting 3.

In this arrangement, as shown in FIG. 1, the movable current-carrying shaft 11 is moved along the imaginary axis Px by the operating mechanism. This allows the movable contact 10 to be brought into contact with and separated from the fixed contact 8. As a result, the vacuum valve P can be opened and closed (i.e., the pair of electrodes E1, E2 can be brought into contact and separated from each other).

In addition, an airtightness maintaining mechanism 4 is disposed between the movable current-carrying shaft 11 and the movable side sealing metal fitting 3. The airtightness maintaining mechanism 4 is made of a bellows having elasticity, and the bellows (airtightness maintaining mechanism) 4 is made of a thin metal such as stainless steel. The bellows 4 is bellows-shaped and can expand and contract in the direction of the imaginary axis Px, and covers the outside of the movable current-carrying shaft 11 without any gaps.

One end of the bellows 4 is tightly joined to the movable sealing metal fitting 3, and the other end is tightly joined to the movable current-carrying shaft 11. This ensures that the inside of the vacuum vessel 1 is always kept airtight (i.e., vacuum state). As a result, when the vacuum valve P is opened or closed, the atmosphere (air) does not enter the inside of the vacuum vessel 1, even while the movable current-carrying shaft 11 is being moved along the imaginary axis Px.

In addition, the vacuum valve P having the basic structure described above is molded into a cylindrical contour using insulating resin 12, thereby constructing it as a molded vacuum valve P. In this case, the insulating resin 12 is added and molded so as to cover the outside of the vacuum vessel 1 (i.e., the outer surface 5s of the arc shield 5 and the outer surface 1s of the insulating porcelain tubes 1a and 1b) without any gaps. The insulating resin 12 is made of a thermosetting resin such as epoxy resin or unsaturated polyester resin.

The vacuum valve P, which is molded into a cylindrical outline using insulating resin 12, is provided with a conductive ground layer 13 that is provided to cover the outside of the insulating resin 12. The ground layer 13 is formed by applying, for example, conductive paint along the outer periphery of the cylindrical insulating resin 12, and is earthed.

The vacuum valve P is further provided with external shields (fixed external shield 6, movable external shield 7) that reduce the concentration of the electric field on the sealing metal fittings 2, 3 when current is applied or when the electrodes are open. In this case, the fixed external shield 6 and the movable external shield 7 are metal members made of a metal (conductive) material such as copper, aluminum, stainless steel, etc.

The fixed side external shield 6 extends in the direction of the imaginary axis Px in a hollow cylindrical shape so as to surround part of the outside of the vacuum vessel 1 (i.e., the fixed side insulating porcelain tube 1a) while covering the fixed side sealing metal fitting 2. The movable side external shield 7 extends in the direction of the imaginary axis Px in a hollow cylindrical shape so as to surround part of the outside of the vacuum vessel 1 (i.e., the movable side insulating porcelain tube 1b) while covering the movable side sealing metal fitting 3.

In such a molded vacuum valve P (vacuum vessel 1), the insulating resin 12, the metal members (i.e., the sealing metal fittings 2, 3, the arc shield 5, the external shields 6, 7), and the insulating members (i.e., the insulating porcelain tubes 1a, 1b) have different linear expansion coefficients (also called thermal expansion coefficients). As a result, for example, the rates at which the lengths and volumes of these three components increase or decrease due to temperature changes are different from one another.

This may cause localized peeling between the insulating resin 12 and the metal members (2, 3, 5, 6, 7) and between the insulating members (1a, 1b), or may cause sink marks due to thermal hardening of the insulating resin 12 itself. If this occurs, voids Ag1, Ag2 (also called air pockets or gaps) where no insulating resin 12 exists may be generated along the interface between the insulating resin 12 and the metal members (2, 3, 5, 6, 7) and/or along the interface between the insulating resin 12 and the insulating members (1a, 1b). As a result, the electric field inside the voids Ag1, Ag2 may become high, causing partial discharges.

Therefore, in order to prevent partial discharges from occurring inside the gaps Ag1 and Ag2, the molded vacuum valve P is provided with a structure (see Figures 3 to 5) for suppressing an increase in the electric field inside the gaps Ag1 and Ag2 when the vacuum valve P is in operation (i.e., when a voltage is applied). As an example, Figure 1 shows gap Ag1 occurring along the interface between the insulating resin 12 and the fixed-side insulating porcelain tube 1a, and gap Ag2 occurring along the interface between the insulating resin 12 and the fixed-side outer shield 6.

Figure 2 is an enlarged view of the structure around gaps Ag1 and Ag2 shown in Figure 1. Figure 2 shows the state in which insulating resin 12 has been added to cover the vacuum vessel 1. In this state, gap Ag1 occurs along a portion of the interface between insulating resin 12 and the fixed-side insulating porcelain tube 1a where stress is likely to concentrate. Gap Ag2 occurs along a portion of the interface between insulating resin 12 and the fixed-side external shield 6 where stress is likely to concentrate.

The ends (edges) of the fixed insulating porcelain tube 1a and the fixed external shield 6 can be assumed to be areas where stress is likely to concentrate. The ends (edges) of other metal members (i.e., the sealing fittings 2, 3, the arc shield 5, the movable external shield 7) and insulating members (i.e., the movable insulating porcelain tube 1b) can also be assumed to be areas where stress is likely to concentrate.

As an example, FIG. 2 shows gaps Ag1 and Ag2 having an arc-shaped cross-sectional contour, but gaps Ag1 and Ag2 having other cross-sectional contours, such as rectangular or triangular, are also envisioned. Although not specifically shown, the planar contours of gaps Ag1 and Ag2 can be envisioned to have contour shapes such as circular, elliptical, triangular, rectangular, etc.

Furthermore, the voids Ag1 and Ag2 occur along the interface between the fixed insulating porcelain tube 1a and the fixed external shield 6, which are hollow cylindrical in shape. In this case, it is generally assumed that the majority of the voids Ag1 and Ag2 are scattered at intervals from each other, but depending on the usage environment and usage conditions, they may be continuous in the circumferential direction.

The size of the gaps Ag1 and Ag2 is not particularly limited here because it is assumed that it will increase or decrease depending on, for example, the flow state of the insulating resin 12 when it is added to cover the vacuum vessel 1, the transition state of the resin until it solidifies, the temperature state acting on the molded vacuum valve P, the state of the linear expansion coefficients (thermal expansion coefficients) of the three components mentioned above (i.e., the insulating resin, the metal member, and the insulating member), and the rate at which the length and volume of each of the three components increase or decrease depending on the linear expansion coefficients (thermal expansion coefficients).

The vacuum valve P has an electric field mitigation means and a moving approach means as components for suppressing an increase in the electric field inside the gaps Ag1 and Ag2 during operation (i.e., when a voltage is applied). The electric field mitigation means will be described later with reference to Figures 3 and 4, and the moving approach means with reference to Figure 5.

As shown in Figures 3 to 5, the electric field relaxation means is added to the insulating resin 12, has electrophoretic properties, and has the function of suppressing an increase in the electric field. The moving proximity means has the function of moving the electric field relaxation means toward the gaps Ag1 and Ag2 to bring them into close proximity. Then, with the electric field relaxation means brought into close proximity to the gaps Ag1 and Ag2, the increase in the electric field inside the gaps Ag1 and Ag2 is suppressed when a voltage is applied, thereby preventing the occurrence of partial discharge inside the gaps Ag1 and Ag2.

The electric field relaxation means is configured with a plurality of electric field relaxation fillers F1, F2 (see Figures 3 to 5). A portion of each of the electric field relaxation fillers F1, F2 is positioned on the entire surface of the gaps Ag1, Ag2 at least close to the triple points P1, P2 described below.

The triple points P1 and P2 refer to the locations where the insulating resin 12, the metal members (2, 3, 5, 6, 7), and the gaps Ag1 and Ag2 are in contact with each other without any gaps, and the locations where the insulating resin 12, the insulating members (1a and 1b), and the gaps Ag1 and Ag2 are in contact with each other without any gaps.

As an example, FIG. 2 shows a triple point P1 where the insulating resin 12, the fixed insulating porcelain tube 1a, and the gap Ag1 are in contact with each other without any gaps, and a triple point P2 where the insulating resin 12, the fixed external shield 6, and the gap Ag2 are in contact with each other without any gaps.

Figures 3 and 4 are diagrams showing the arrangement of electric field relaxation fillers F1 and F2. Figure 3 shows the state in which electric field relaxation fillers F1 and F2 are arranged in close proximity over the entire surface of gaps Ag1 and Ag2. Figure 4 shows the state in which electric field relaxation fillers F1 and F2 are arranged in close proximity to triple points P1 and P2 of gaps Ag1 and Ag2. As an example, in Figures 3 and 4, the electric field relaxation filler arranged in close proximity to gap Ag1 is indicated by the symbol F1, while the electric field relaxation filler arranged in close proximity to gap Ag2 is indicated by the symbol F2.

In this case, it is preferable that the electric field relaxation filler F1 arranged close to the triple point P1 contacts the fixed side insulating porcelain tube 1a without any gaps. On the other hand, it is preferable that the electric field relaxation filler F2 arranged close to the triple point P2 contacts the fixed side external shield 6 without any gaps. Note that the electric field relaxation fillers F1 and F2 do not necessarily need to contact the triple points P1 and P2 without any gaps, and they may simply be close to the vicinity of the triple points P1 and P2 (i.e., at a position not in contact with the triple points P1 and P2).

Figure 5 is a conceptual diagram of the moving approach means. In the moving approach means shown in Figure 5, insulating resin 12 to which electric field mitigation fillers F1 and F2 have been added in advance is added to the outside of the vacuum vessel 1, and after molding into a predetermined shape, a DC voltage is applied to the metal member adjacent to the interface where gaps Ag1 and Ag2 are generated and to the charged insulating member. In Figure 5, as an example, a DC voltage is applied to the fixed side external shield 6 and the charged fixed side insulating porcelain tube 1a, respectively.

At this time, it is preferable that the electric field relaxation fillers F1 and F2 previously added to the insulating resin 12 are aggregated in the insulating resin 12 in the regions adjacent to the voids Ag1 and Ag2, and are dispersed in other regions.

Here, the electric field relaxation fillers F1 and F2 each include a conductive filler that imparts conductivity (i.e., the property of making it easier for electricity to pass) to the insulating resin 12, and a low dielectric constant filler that imparts dielectric properties (i.e., the property of making it difficult for electricity to pass) to the insulating resin 12. In this case, one or both of the conductive filler and the low dielectric constant filler are added to the insulating resin 12.

In this case, it is preferable to add both a conductive filler and a low dielectric constant filler to the insulating resin 12. When the conductive filler is placed close to the gap Ag1 adjacent to the insulating member (i.e., the insulating porcelain tube 1a), it can cause a problem of acting as a metallic foreign body. However, by adding both the conductive filler and the low dielectric constant filler to the insulating resin 12, it is possible to place both the conductive filler and the low dielectric constant filler close to the gap Ag1, thereby resolving the above problem.

On the other hand, it is preferable to charge the low dielectric constant filler. Low dielectric constant fillers have the property of making it difficult for electricity to pass through them, but by charging them in advance, they can be made into electric field relaxation fillers F1 and F2 that have electrophoretic properties.

In addition, it is preferable to set the dielectric constant ε1 of the low dielectric constant filler to be smaller than the dielectric constant ε2 of the insulating resin (i.e., to satisfy the relationship ε1 < ε2). If the dielectric constant ε1 of the low dielectric constant filler is larger than the dielectric constant ε2 of the insulating resin, a problem occurs in which the electric field strength of the gap Ag2 adjacent to the metal member (i.e., the fixed-side external shield 6) is increased, but by satisfying the relationship ε1 < ε2, the above problem can be solved.

By applying a DC voltage to the fixed external shield 6 and the charged fixed insulating porcelain tube 1a, respectively, both the conductive filler and the charged low dielectric constant filler can be efficiently moved toward and brought into close proximity to the nearest gaps Ag1 and Ag2 in a time shorter than the so-called gel time (i.e., the time it takes for the insulating resin 12 to lose its fluidity and rapidly increase in viscosity).

Figure 6 is a comparative diagram showing the relationship between the presence or absence of electric field relaxation fillers F1, F2 and the maximum electric field strength generated in the gaps Ag1, Ag2. This shows that when the electric field relaxation fillers F1, F2 are closely arranged so as to cover the entire surface of the gaps Ag1, Ag2 (or at least the vicinity of the triple points P1, P2), the maximum electric field strength generated in the gaps Ag1, Ag2 is significantly smaller than when the electric field relaxation fillers F1, F2 are not present.

As described above, according to this embodiment, if voids Ag1 and Ag2 occur when insulating resin 12 is added to cover the vacuum vessel 1, electric field mitigation fillers F1 and F2 are placed in close proximity to cover the entire surface of the voids Ag1 and Ag2 (or at least the vicinity of triple points P1 and P2). This makes it possible to suppress the rise in the electric field inside the voids Ag1 and Ag2 (in other words, to mitigate the electrical stress generated inside the voids Ag1 and Ag2) when the vacuum valve P is in operation (i.e., when voltage is applied). As a result, it is possible to prevent partial discharges from occurring inside the voids Ag1 and Ag2.

In this case, by arranging the electric field relaxation fillers F1 and F2 closely so as to cover the entire surface of the voids Ag1 and Ag2, the electric field strength generated inside the voids Ag1 and Ag2 can be significantly reduced. Here, since the electric field strength near the triple points P1 and P2 of the voids Ag1 and Ag2 is the highest within the voids Ag1 and Ag2, even when the electric field relaxation fillers F1 and F2 are closely arranged so as to cover the area near the triple points P1 and P2, the same electric field relaxation effect can be achieved as when the entire surface of the voids Ag1 and Ag2 is covered.

Furthermore, according to this embodiment, by adding the electric field relaxation fillers F1 and F2 to the insulating resin 12 in advance, it is possible to arrange the electric field relaxation fillers F1 and F2 in close proximity to the gaps Ag1 and Ag2 without establishing a new manufacturing process and by utilizing the normally performed manufacturing process as is. As a result, it is possible to prevent the occurrence of partial discharges inside the gaps Ag1 and Ag2 without increasing manufacturing costs.

"Variations"
In this modification, a plurality of electric field relaxation fillers F1, F2 are added to the insulating resin 12 in advance along the periphery of the voids Ag1, Ag2 that are generated in the portion where stress is likely to concentrate. This allows the fillers to be efficiently moved toward and close to the nearest voids Ag1, Ag2 in a time shorter than the so-called gel time (i.e., the time it takes for the insulating resin 12 to lose its fluidity and its viscosity to increase rapidly). Note that other configurations and effects are the same as those of the above embodiment, and therefore description thereof will be omitted.

Although one embodiment of the present invention and modifications have been described above, these embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. These embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims.

P...vacuum valve, Px...virtual axis, E1...fixed electrode, E2...movable electrode, 1...vacuum vessel, 1a...fixed insulating tube, 1b...movable insulating tube, K1...fixed opening, K2...movable opening, 2...fixed sealing metal fitting, 3...movable sealing metal fitting, 4...airtightness maintaining mechanism, 5...arc shield, 6...fixed outer shield, 7...movable outer shield, 8...fixed contact, 9...fixed current-carrying shaft, 10...movable contact, 11...movable current-carrying shaft, 12...insulating resin, 13...ground layer, Ag1, Ag2...gap, P1, P2...triple point, F1, F2...electric field relaxation filler.

Claims (7)

a vacuum vessel formed by combining a metal member and an insulating member so as to house a pair of electrodes in a releasable manner;
an insulating resin molded to cover the vacuum vessel;
an electric field relaxation means which is added to the insulating resin, has electrophoretic properties, and has a function of suppressing an increase in the electric field;
a moving and approaching means for moving the electric field mitigation means toward and approaching the electric field mitigation means when a gap where no insulating resin is present occurs along a portion of the interface between the insulating resin and the metal member and/or the interface between the insulating resin and the insulating member where stress is likely to concentrate, in a state where the insulating resin is added so as to cover the vacuum container,
A vacuum valve that prevents the occurrence of partial discharge within the gap by suppressing an increase in the electric field within the gap when a voltage is applied with the electric field mitigation means brought close to the gap. The electric field mitigation means is disposed close to at least the triple point on the entire surface of the gap,
The vacuum valve according to claim 1, wherein the triple point refers to a location where the insulating resin, the metal member, and the gap are in contact with each other without any gaps, and a location where the insulating resin, the insulating member, and the gap are in contact with each other without any gaps. the electric field mitigation means is disposed close to the triple point where the insulating resin, the metal member, and the void are in contact with each other without any gaps, and is in contact with the metal member without any gaps;
3. The vacuum valve according to claim 2, wherein the electric field relaxation means arranged close to the triple point where the insulating resin, the insulating member and the gap are in contact with one another without any gaps contacts the insulating member without any gaps. the electric field relaxation means is configured to include a plurality of electric field relaxation fillers,
When arranging a portion of the plurality of electric field relaxation fillers in proximity to at least the triple point on the entire surface of the void,
4. The vacuum valve according to claim 2, wherein the plurality of electric field relaxation fillers are aggregated in the region adjacent to the gap and are dispersed in the other region. The vacuum valve according to claim 4, in which a plurality of the electric field relaxation fillers are added to the insulating resin in advance along the periphery of the voids that occur in areas where stress is likely to concentrate. the electric field relaxation filler includes a conductive filler that imparts electrical conductivity to the insulating resin and a low dielectric constant filler that imparts dielectric properties to the insulating resin;
5. The vacuum valve according to claim 4, wherein the insulating resin contains one or both of the conductive filler and the low dielectric constant filler. If the dielectric constant of the low dielectric constant filler is ε1 and the dielectric constant of the insulating resin is ε2, then
7. The vacuum valve according to claim 6, wherein the dielectric constant of the low dielectric constant filler is set so as to satisfy the relationship ε1<ε2.

Images