JP2009205801A - Vacuum switch - Google Patents

Abstract

【Task】
An object of the present invention is to provide a vacuum switch that is insulated and molded so as to prevent cracks and breakage of a mold member.
[Solution]
A vacuum vessel 20 that houses at least a pair of fixed-side electrode 13 and movable-side electrode 12 facing the fixed-side electrode 13, has a vacuum inside, and has a step portion in the radial direction on the outer peripheral surface; In the vacuum switch 10 comprising: the stress relaxation member 4 that collectively covers the empty container 20 including the stepped portion; and the insulating resin 2 that collectively insulates the vacuum container and the stress relaxation member. The annular elastic body 6 surrounding the vacuum vessel 20 is disposed or held in the stepped portion.
[Selection] Figure 1

Description

  The present invention relates to a vacuum switch, and more particularly, to a vacuum switch suitable for a power distribution switchgear in which an outer surface of a vacuum vessel is insulation-molded.

  A vacuum switch is a switch that takes advantage of the high current interruption performance and dielectric strength of a vacuum, is compact and highly reliable, and is widely applied to switchgear for power distribution (hereinafter referred to as switchgear). It is what.

  In recent years, the number of vacuum switches that mold the entire surface of a vacuum vessel with a resin such as epoxy having a higher dielectric strength than the atmosphere has increased in order to further reduce the size of the switchgear and prevent the insulation performance of the vacuum switch from decreasing. ing.

  Resins such as epoxy have a higher dielectric strength than the atmosphere, so the insulation distance can be shortened compared to the case where the surface of the vacuum container is covered with the atmosphere, reducing the space required to ensure the insulation of the vacuum container. Therefore, the switchgear can be made compact.

  In addition, by molding the entire surface of the vacuum vessel with resin, it prevents the fouling substances such as moisture and dust from adhering to the vacuum vessel, and the insulation performance of the vacuum switch caused by the fouling matter adhering to the vacuum vessel. Decline can be prevented.

  However, when the entire surface of the vacuum vessel is directly molded with resin, the thermal expansion coefficients of the resin and the insulating cylinder constituting the vacuum vessel are different. Thermal stress based on the difference occurs. For example, when the impact force generated during the opening / closing operation is transmitted to the resin due to the thermal stress, the resin may be cracked or peeled off due to the impact force. The site where the crack or peeling occurs causes a partial discharge and has a problem that the dielectric strength decreases.

  Further, as a vacuum valve having a function of preventing cracking and peeling of the resin caused by different thermal expansion coefficients of the resin and the insulating cylinder constituting the vacuum container, for example, the insulating cylinder and the end plate constituting the vacuum container Are collectively covered with rubber, and then they are collectively molded with an insulator.

  Furthermore, as a vacuum valve having a function that enables electric field concentration relaxation at the corners of the vacuum vessel, there is one described in Patent Document 1, for example. In Patent Document 1, by applying conductive thermal stress relaxation members to several edge portions (corner portions) protruding in the outer peripheral direction of the vacuum vessel, and molding the outer peripheral surface of the vacuum vessel integrally with a resin, A vacuum valve is described in which electric field concentration relaxation and thermal stress relaxation at the edge portion are achieved.

Japanese Patent Laid-Open No. 2002-358861

  However, in a vacuum container composed of an insulating cylinder and an end plate, a difference in thickness between the two causes a stepped portion in the axial direction at the boundary portion between the insulating cylinder and the end plate. If the rubber is covered with rubber at the same time, the corners of the stepped portion press the rubber, and the rubber becomes thin at the corners of the stepped portion and the rubber is easily broken. When the rubber breaks at the corner of the stepped portion, the resin may crack or peel off due to thermal stress at the corner of the stepped portion after molding.

  In addition, in the vacuum valve described in Patent Document 1, it is difficult in the first place to fix the conductive thermal stress relaxation member to the edge portion of the outer peripheral surface of the vacuum vessel, and when the outer peripheral surface of the vacuum vessel is molded with resin. Further, there is a possibility that the conductive thermal stress relaxation member is detached. When the conductive thermal stress relaxation member is detached, the electric field concentration relaxation cannot be achieved.

  Furthermore, the scale of the thermal deformation of the resin after molding the resin at a high temperature due to the difference in the thermal expansion coefficient of the ceramic cylindrical body, the conductive thermal stress relaxation member, and the resin constituting the vacuum vessel In the vicinity of the triple point where the ceramic tubular body, the conductive thermal stress relaxation member, and the resin face each other, the stress concentration is excessive, and the ceramic tubular body is larger than the conductive thermal stress relaxation member side. There was a problem that the body and the resin peeled, causing partial discharge, and the dielectric strength was likely to be lowered.

  The present invention has been made in view of the above points, and the object thereof is to provide a corner portion of the step portion even if a step portion is generated in the axial direction of the vacuum vessel without providing a special thermal stress relaxation member. An object of the present invention is to provide a vacuum switch that prevents cracking and peeling of the mold member due to the above and does not lower the dielectric strength.

  In order to achieve the above object, a vacuum switch according to the present invention accommodates at least a pair of a fixed side electrode and a movable side electrode facing the fixed side electrode, and has a vacuum inside, and a shaft in the middle of the outer peripheral surface. A vacuum vessel having a direction step portion, an insulating resin that insulatively molds the outer surface of the vacuum vessel, and between the vacuum vessel and the insulating resin and so as to include a step portion of the vacuum vessel A vacuum switch provided with a stress relaxation member that relieves thermal stress due to a difference in thermal expansion coefficient between the insulating resin and the vacuum vessel, and is surrounded by the outer peripheral surface of the vacuum vessel and the stress relaxation member A ring-shaped elastic body is arranged at the step portion.

  According to the present invention, even if a step portion is generated in the axial direction of the vacuum vessel without providing a special thermal stress relaxation member, it prevents the mold member from cracking or peeling off at the corner portion of the step portion, thereby providing a dielectric strength. It is possible to obtain a vacuum switch that does not drop.

  Even if there is a step in the axial direction of the vacuum vessel without providing a special thermal stress relief member, the vacuum switch does not decrease the dielectric strength by preventing cracks and peeling of the mold member by the corner of the step The purpose of providing is realized with a simple configuration.

  An embodiment of the vacuum switch according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a sectional view of an embodiment of a vacuum switch according to the present invention. The vacuum switch 10 includes a vacuum vessel 20, a fixed side electrode 13 accommodated in the vacuum vessel 20, and the fixing device. The movable electrode 12 is arranged to be opposed to the side electrode 13 so as to be movable up and down, and a solid insulating skin 2 (insulating resin) that insulates the entire outer surface of the vacuum vessel 20.

  The vacuum vessel 20 includes a movable end plate 21 and a fixed end plate 22 made of copper, and ceramic insulating cylinders 1 a and 1 b disposed between the movable end plate 21 and the fixed end plate 22. The movable side end plate 21 and the insulating cylinder 1a are connected to each other, and the fixed side end plate 22 and the insulating cylinder 1b are connected to each other. In addition, the radial thickness of the insulating cylinders 1a and 1b is thicker than the radial thickness of the movable side end plate 21 and the fixed side end plate 22, and the movable side end plate 21, the insulating cylinder 1a and the fixed side end plate are formed. When 22 and the insulating cylinder 1b are connected, an axial step portion is generated at the boundary portion between the two due to the difference in the radial thickness between the two. Insulating cylinders 1a and 1b made of ceramics have a baked metal portion on the end face connected to the movable side end plate 21 and the fixed side end plate 22, and are opened and closed between the insulating cylinder 1a and the insulating cylinder 1b. An arc shield 16 is sometimes sandwiched to shield an arc generated from the electrode. Further, between the movable shaft 14 and the movable side end plate 21, one end is connected to the movable side end plate 21, the other end is connected to the movable shaft 14, and the bellows 23 that moves in conjunction with the movable shaft 14 are airtight. Is sealed.

  The fixed side electrode 13 is supported by one end of a copper fixed shaft 15, and the fixed shaft 15 is fixed through the vacuum vessel 20. For example, an external cable on the bus side or load side is connected to the other end. Is done. On the other hand, the movable electrode 12 is supported by one end of a copper movable shaft 14, the movable shaft 14 penetrates the vacuum vessel 20, and the other end is supported by a movable insulating rod 8 connected to an external operation mechanism. The movable mechanism is moved up and down by the operation mechanism, and opens and closes the fixed side electrode 13 and the movable side electrode 12. The movable shaft 14 is connected to a high-voltage conductor 30 outside the vacuum vessel, and a load-side or bus-side conductor, for example, is connected to the high-voltage conductor 30.

  Further, the vacuum container 20 and the heat shrinkable tube 4 are insulated and molded by the solid insulating skin 2, and the surface of the solid insulating skin 2 is covered with the ground conductive layer 3.

  In this embodiment, the conductive ring-like elastic body 6a and the axially stepped portion formed at the boundary portion of the connecting portion between the movable side end plate 21 and the insulating cylinder 1a and the fixed side end plate 22 and the insulating cylinder 1b 6b, for example, conductive silicone rubber in which conductive particles such as carbon black and metal powder are mixed with silicone rubber is disposed. The ring-shaped elastic bodies 6a and 6b are held by their own elastic force so as to surround the periphery of the end portions of the movable side end plate 21 and the fixed side end plate 22, and their cross-sectional shapes are shown in FIG. As shown, it has a substantially circular shape.

  Moreover, the outer peripheral surfaces of the ring-shaped elastic bodies 6a and 6b, the insulating cylinders 1a and 1b, the above-described stepped portions, the partial surfaces of the movable side end plate 21 and the fixed side end plate 22 are mainly composed of the solid insulating outer skin 2 and the vacuum vessel 20. Are collectively covered with a heat shrinkable tube 4 which is a stress relieving member for the purpose of relieving the thermal stress of the ring-like elastic body 6. It is strongly fixed by being sandwiched between the movable side end plate 21 and the fixed side end plate 22. Further, as shown in FIG. 3, the outer circumferences of the ring-shaped elastic bodies 6a and 6b are arranged substantially in line with the outer circumference of the insulating cylinder 1b (or 1a) which is the longer side in the radial direction among the stepped portions.

  The heat shrinkable tube 4 described above needs to withstand the temperature at the time of molding. For example, a heat resistant resin such as a silicone resin or a fluororesin is used.

  Next, the operation of the vacuum switch 10 in the configuration of the above-described embodiment will be described.

  When the movable insulating rod 8 moves up and down by an operating mechanism (not shown) installed outside, the movable shaft 14 supported by the movable insulating rod 8 moves up and down in conjunction with the movable insulating rod 8. Along with this, the movable side electrode 12 supported on one end of the movable shaft 14 also moves up and down and comes in contact with and separates from the fixed side electrode 13 to perform an opening / closing (opening and closing) operation. When the movable side electrode 12 and the fixed side electrode 13 come into contact with each other, the high voltage conductor 30 connected to the movable shaft 14 via the movable shaft 14 and the fixed shaft 15 is connected to the load side or bus side conductor. The current is applied to the external cable on the busbar side or load side connected to the fixed shaft 15.

  Next, a method for forming the solid insulating outer skin 2 by placing the conductive ring-shaped elastic bodies 6a and 6b and the heat shrinkable tube 4 and then casting and molding the resin will be described.

  First, the ring-shaped elastic bodies 6a and 6b are connected to the step portions formed at the connecting portions of the movable side end plate 21 and the fixed side end plate 22 and the insulating cylinders 1a and 1b, and the movable side end plate 21 and the fixed side end plate 22 are connected. It is placed around the periphery and held by its own elastic force. After the ring-shaped elastic bodies 6a and 6b are held by the above-described stepped portions, the insulating cylinders 1a and 1b, the ring-shaped elastic bodies 6a and 6b, the end portions of the movable side end plate 21 and the fixed side end plate 22 are collectively heat-shrinked. Covered with the tube 4, the elastic elastic members 6 a and 6 b are fixed to the surface of the vacuum container 20 by the elastic force of the heat shrinkable tube 4. After disposing the heat shrinkable tube 4 in this way, a resin such as epoxy is molded on the entire surface of the vacuum vessel 20 to form the solid insulating skin 2. After the molding operation is completed, the ground conductive layer 3 is provided on the surface of the solid insulating skin 2.

  By adopting the configuration of the present embodiment described above, the insulating cylinder 1a in the axial step portion formed at the boundary portion of the connecting portion between the movable side end plate 21 and the insulating cylinder 1a and the fixed side end plate 22 and the insulating cylinder 1b. In the vicinity of the corners of the insulating cylinders 1a and 1b, in addition to the compressive force from the corners of the insulating cylinders 1a and 1b, the repulsive force from the ring-shaped elastic bodies 6a and 6b acts on the heat-shrinkable tube 4. Thus, the compressive force applied to the heat shrinkable tube 4 can be dispersed. Thereby, breakage of the heat-shrinkable tube 4 can be prevented, and cracks and breakage of the solid insulation outer shell 2 can be prevented at the corners of the insulating cylinders 1a and 1b, and the reliability of the vacuum switch 10 can be improved. .

  Further, in this embodiment, the ring-shaped elastic bodies 6a and 6b are held by the movable side end plate 21 and the fixed side end plate 22 and further covered and fixed by the heat shrinkable tube 4, so that the ring-shaped elastic bodies 6a are molded. , 6b is eliminated, and workability is not reduced.

  In the present embodiment, since the ring-shaped elastic bodies 6a and 6b are conductive, the electric field concentration generated in the corners of the insulating cylinders 1a and 1b and the gaps 51 to 53 can be reduced, and the ring-shaped elastic bodies 6a and 6b 6b is held by the movable side end plate 21 and the fixed side end plate 22 and further covered and fixed by the heat shrinkable tube 4, so that the risk of the ring-like elastic bodies 6a and 6b coming off at the time of molding can be reduced. Electric field concentration relaxation can be achieved.

  In the present embodiment described above, the cross-sectional shapes of the ring-shaped elastic bodies 6a and 6b are circular as shown in FIG. 2, but for example, as shown in FIG. By making the cross-sectional shape of 6b thicker on the side close to the surface where the level difference exists, for example, in a wedge shape that becomes thinner on the far side, the entire gap can be reduced, and the electric field concentrated in the gap can be easily relaxed. This is effective.

  Moreover, if the air pushed out when the heat shrinkable tube 4 shrinks remains between the insulating cylinders 1a and 1b and the heat shrinkable tube 4, partial discharge may occur and the dielectric strength may be reduced.

  In such a case, as shown in FIG. 5, by providing a hole 6c such as a recess in a part of the ring-shaped elastic bodies 6a and 6b in the circumferential direction, air is formed when the heat-shrinkable tube 4 contracts. The air is reliably exhausted through 6c, and the residual air between the insulating cylinders 1a and 1b and the heat-shrinkable tube 4 can be reduced, and the decrease in the dielectric strength due to the remaining air can be suppressed.

  Next, another embodiment of the vacuum switch according to the present invention will be described with reference to FIG.

  In this embodiment, instead of disposing the conductive ring-shaped elastic body described in the above-described embodiment, as shown in FIG. 6, the heat shrinkable tube 4 in the vicinity of the step portion in the axial direction is made of, for example, conductive silicone rubber. A conductive portion 4c is provided. The conductive portion 4c has a thick section at the end face side of the insulating cylinders 1a and 1b having a stepped portion and a thin side far from the end faces of the insulating cylinders 1a and 1b in the axial direction. The thin portion of the conductive portion 4 c is in contact with the movable side end plate 21 or the fixed side end plate 22.

  At this time, the thickest width in the radial direction of the conductive portion 4c is set to be substantially equal to the radial width of the stepped portion when the heat-shrinkable tube 4 is disposed, and after the heat-shrinkable tube 4 is disposed. In the same manner as in the above-described embodiment, a resin such as epoxy is molded on the entire surface of the vacuum vessel 20 to form the solid insulating skin 2, and the ground conductive layer 3 is provided on the surface of the solid insulating skin 2.

  In this embodiment, the heat-shrinkable tube 4 is provided with the conductive portion 4c in advance, and the conductive portion 4c is located on the short side in the radial direction in the position corresponding to the step portion described in the above-described embodiment. It is arranged in contact with the movable side end plate 21 or the fixed side end plate 22 that hits the part, and the compressive force applied to the heat shrinkable tube 4 from the corners of the insulating cylinders 1a and 1b can be dispersed.

  Thereby, breakage of the heat-shrinkable tube 4 can be prevented, cracks and breakage of the solid insulation outer shell 2 can be prevented at the corners of the insulating cylinders 1a and 1b, and the reliability of the vacuum switch 10 can be improved. . Further, in order to efficiently disperse the compressive force applied to the heat-shrinkable tube 4 from the corners of the insulating cylinders 1a and 1b, the conductive portion 4c may be disposed as close as possible to the insulating cylinder 1 so as to contact, for example. desirable.

  In addition, since the conductive portion 4c is provided in the heat-shrinkable tube 4 in advance, there is no fear that the ring-shaped elastic body used in the above-described embodiment will be removed during molding, and the conductive portion 4c is disposed at the step portion. As a result, electric field concentration relaxation can be achieved.

  In the present embodiment, the width in the radial direction of the conductive portion 4c provided in the heat shrinkable tube 4 is made substantially equal to the width in the radial direction of the step portion when the heat shrinkable tube 4 is disposed. Since the gap between the conductive portion 4c and the heat-shrinkable tube 4 and the vacuum vessel 20 can be reduced and the reduced gap can be occupied by the conductive portion 4c having a dielectric constant larger than that of the atmosphere, electric field concentration relaxation can be achieved. Can be planned.

  By providing the conductive portion 4c in advance in the heat-shrinkable tube 4, it is possible to reduce the gaps 51 and 53 as compared with the case where the annular elastic body as in the above-described embodiment is fixed alone. Compared with the embodiment, the electric field concentration can be further reduced.

  Further, based on the same idea as in the embodiment shown in FIG. 5, by providing a hole such as a recess in a part in the circumferential direction of the conductive portion 4c, the residual air when the heat-shrinkable tube 4 is arranged is reduced. As a result, it is possible to suppress a decrease in dielectric strength due to air remaining.

  Even if there is a step in the axial direction of the vacuum vessel without providing a special thermal stress relief member, the vacuum switch does not decrease the dielectric strength by preventing cracks and peeling of the mold member by the corner of the step Therefore, it is effective for a power distribution switchgear.

It is sectional drawing which shows one Example of the vacuum switch of this invention. It is an expanded sectional view of the vicinity of a ring-shaped elastic body employed in an embodiment of the present invention. It is sectional drawing which expands and shows the part shown in FIG. It is an enlarged view of the axial sectional view of the vicinity of the ring-shaped elastic body showing another example of the ring-shaped elastic body employed in one embodiment of the present invention. It is sectional drawing of the annular elastic body which shows the example which provided the hole in a part of circumferential direction of the annular elastic body. It is an expanded sectional view of the ring-shaped elastic body part which shows the other Example of the vacuum switch of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Insulating cylinder 2 Solid insulation outer shell 3 Ground conductive layer 4 Heat-shrinkable tubes 6a, 6b Annular elastic body 7 Cable connecting part 8 Movable insulating rod 10 Vacuum switch 12 Movable electrode 13 Fixed electrode 14 Movable shaft 15 Fixed shaft 16 Arc shield 20 Vacuum container 21 Movable side end plate 22 Fixed side end plate 23 Bellows 30 High voltage conductors 51 to 53 Air gap

Claims (10)

A vacuum container that houses at least a pair of a fixed side electrode and a movable side electrode facing the fixed side electrode, and has a vacuum inside and an axial step in the middle of the outer peripheral surface; and An insulating resin that insulatively molds the outer surface, and is disposed between the vacuum container and the insulating resin so as to include a stepped portion of the vacuum container, and has a coefficient of thermal expansion between the insulating resin and the vacuum container. In a vacuum switch equipped with a stress relaxation member that relieves thermal stress due to differences,
A vacuum switch comprising a ring-shaped elastic body disposed on the stepped portion surrounded by the outer peripheral surface of the vacuum vessel and a stress relaxation member. It consists of an insulating cylinder and a movable side end plate and a fixed side end plate connected to both ends in the axial direction of the insulating cylinder, and at least a pair of a fixed side electrode and a movable side electrode facing the fixed side electrode are housed inside the vacuum. A vacuum vessel having an axial step on the outer peripheral surface of the connecting portion between the insulating cylinder and the movable side end plate and the insulating cylinder and the fixed side end plate, and an insulating property for insulating molding the outer surface of the vacuum vessel A stress that is disposed between the resin and the vacuum vessel and the insulating resin so as to include a step portion of the vacuum vessel, and relieves thermal stress due to a difference in thermal expansion coefficient between the insulating resin and the vacuum vessel. In a vacuum switch equipped with a relaxation member,
A vacuum opening and closing characterized in that a ring-shaped elastic body is disposed on the stepped portion surrounded by the outer peripheral surface of the connecting portion where the insulating cylinder and the movable side end plate and the insulating cylinder and the fixed side end plate are connected and the stress relaxation member vessel. In the vacuum switch according to claim 1 or 2,
A vacuum switch according to claim 1, wherein the ring-shaped elastic body is conductive. A ceramic insulating cylinder and a movable side end plate made of copper and a fixed side end plate connected to both ends of the insulating cylinder in the axial direction and having a thickness smaller than the radial thickness of the insulating cylinder. And at least a pair of movable side electrodes opposed to the fixed side electrode, and the insulating cylinder and the movable side end plate on the outer peripheral surface of the connecting portion between the insulating cylinder and the movable side end plate and the insulating cylinder and the fixed side end plate. And a vacuum vessel having an axial step due to a difference in thickness between the fixed side end plate, an insulating resin that insulates the outer surface of the vacuum vessel, and the vacuum vessel and the insulating resin. And a vacuum switch comprising a stress relaxation member that is disposed so as to include a stepped portion of the vacuum vessel and that relieves thermal stress due to a difference in thermal expansion coefficient between the insulating resin and the vacuum vessel.
The axial end face of the insulating cylinder, the movable side end plate, the stepped portion surrounded by the stress relaxation member, and the axial end surface of the insulating cylinder, the fixed side end plate, and the stepped portion surrounded by the stress relaxation member. A vacuum switch characterized in that a conductive ring-shaped elastic body is disposed in each. In the vacuum switch according to claim 1, 2, or 4,
The vacuum switch according to claim 1, wherein the ring-shaped elastic body has a circular cross section. In the vacuum switch according to claim 1, 2, or 4,
The ring-shaped elastic body is a vacuum switch characterized in that the cross section is thick on the side of the stepped portion and thin on the side far from the stepped portion in the axial direction. In the vacuum switch according to claim 1, 2, or 4,
A vacuum switch according to claim 1, wherein a hole for exhausting air between the vacuum vessel and the stress relaxation member is provided in a part of the annular elastic body in the circumferential direction. A ceramic insulating cylinder and a movable side end plate made of copper and a fixed side end plate connected to both ends of the insulating cylinder in the axial direction and having a thickness smaller than the radial thickness of the insulating cylinder. And at least a pair of movable side electrodes opposed to the fixed side electrode, and the insulating cylinder and the movable side end plate on the outer peripheral surface of the connecting portion between the insulating cylinder and the movable side end plate and the insulating cylinder and the fixed side end plate. And a vacuum vessel having an axial step due to a difference in thickness between the fixed side end plate, an insulating resin that insulates the outer surface of the vacuum vessel, and the vacuum vessel and the insulating resin. And a vacuum switch comprising a stress relaxation member that is disposed so as to include a stepped portion of the vacuum vessel and that relieves thermal stress due to a difference in thermal expansion coefficient between the insulating resin and the vacuum vessel.
The stress relaxation member in the vicinity of the step portion in the axial direction of the vacuum vessel is provided with a conductive portion whose cross section is thick on the end side of the insulating cylinder of the step portion and thin on the side far from the end surface of the insulating cylinder in the axial direction. A vacuum switch characterized in that a thin part is in contact with the movable side end plate or the fixed side end plate. In the vacuum switch according to any one of claims 1, 2, 4, or 7,
The vacuum switch characterized in that the surface of the insulating resin is covered with a ground conductive layer. In the vacuum switch according to any one of claims 1, 2, 4, or 7,
The vacuum switch according to claim 1, wherein the insulating resin is a heat-resistant resin made of silicone resin or fluorine resin.

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