JP4660303B2 - Solid insulation switchgear - Google Patents

Description

  The present invention relates to a solid-insulated switchgear in which main circuit electric devices such as vacuum valves and connection conductors constituting a power supply system are molded with an insulating material, and more particularly to a solid-insulated switchgear that can improve partial discharge characteristics.

  Conventionally, in a main circuit electric device such as a vacuum valve and a connection conductor constituting a main circuit of a switchgear, a solid insulation type in which an insulating outer skin is formed by molding with an insulating material such as an epoxy resin is known. (For example, refer to Patent Document 1).

  However, since the end of the sealing fitting constituting the vacuum valve has an acute angle shape, stress concentration may occur in the insulating outer skin, and cracks may occur. In addition, the electric field strength increases, and the withstand voltage characteristics may be reduced.

In order to solve this, a technique is known in which an acute-angled portion such as a sealing metal fitting is covered with a round metal shield (see, for example, Patent Document 2). Thereby, the stress concentration of the insulating outer skin is suppressed, and electric field relaxation can be achieved.
JP 2001-286018 A (page 4, FIG. 4) JP-A-9-82186 (3rd page, FIG. 1)

The above-described conventional solid-insulated switchgear has the following problems.
Since the mutual thermal expansion coefficient differs at the interface between the shield covering the sealing fitting or the like and the insulating outer skin, peeling may occur due to temperature changes during molding or operation. In addition, since different materials of a metal material and an insulating material are bonded, it is difficult to keep the adhesive force strong, and the material may be peeled off. When peeling occurs, the electric field strength in this portion increases, partial discharge occurs, and tracking, trees, etc. develop in the insulating shell. This is a phenomenon of insulation deterioration and eventually leads to dielectric breakdown.

  For this reason, there has been a demand for an insulating structure that does not cause insulation deterioration even if partial discharge occurs and does not cause dielectric breakdown. Here, even if partial discharge occurs, if insulation deterioration does not occur, partial discharge characteristics are improved.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid-insulated switchgear that can improve partial discharge characteristics.

In order to achieve the above object, a solid insulated switchgear according to the present invention is a solid insulated switchgear comprising a main circuit electrical device molded with an insulating material to form a main insulation, and constituting a power supply system. The circuit electrical device is a vacuum valve, and is characterized in that an inorganic insulator having a curved portion formed on an inner peripheral surface is provided so as to surround an end portion of a sealing fitting of the vacuum valve .

  According to the present invention, an inorganic insulator is provided so as to surround an electric field strength increasing portion where the electric field strength of the main circuit electrical equipment is increased, and the insulating layer serving as the main insulating is formed by integrally molding these with an insulating material. Since it is formed, the progress of partial discharge is prevented by the inorganic insulator, and the partial discharge characteristics of the main insulation can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a solid insulation switchgear according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view showing a part of a configuration of a solid insulation switchgear according to a first embodiment of the present invention, and FIG. 2 is a block diagram of a blocking portion used in the solid insulation switchgear according to the first embodiment of the present invention. It is sectional drawing which shows a structure.

  As shown in FIG. 1, the solid insulation switchgear includes a main circuit including a cable portion 1a on the back side, an opening / closing portion 1b on the center portion, and a busbar portion 1c on the front side.

  A cable head 2 is provided in the cable portion 1 a, and a power cable 4 penetrating the current transformer 3 is connected to the cable head 2.

  The opening / closing portion 1 b is provided with a blocking portion 5, and one main circuit end of the blocking portion 5 is connected to the main circuit end of the cable head 2 by a U-shaped connection conductor 6. The connection conductor 6 is molded with an organic insulating material such as epoxy resin around a center conductor (not shown).

  The shut-off unit 5 is provided with a vacuum valve 7 having a pair of contact points that can be contacted and separated. Further, for example, an annular inorganic insulator 8 made of an inorganic insulating material such as ceramic or mica is attached to the sealing fittings 7a and 7b for sealing both ends of the insulating container of the vacuum valve 7. It is provided to surround. An insulating layer 9 formed by integrally molding an organic insulating material such as an epoxy resin is provided around the vacuum valve 7 and the inorganic insulator 8.

  An operation mechanism 11 that opens and closes a pair of contacts in the vacuum valve 7 is provided on the movable side serving as the other main circuit end of the blocking portion 5 via an insulating operation rod 10 in the axial direction. In a direction orthogonal to the axial direction, the movable conductor 12 connected to the vacuum valve 7 is in sliding contact with one end of the molded connecting conductor 13.

  The bus bar portion 1 c is provided with a disconnecting portion 15 using a vacuum valve 14 similar to the blocking portion 5. In addition, inorganic insulators 16 are provided at both ends of the vacuum valve 14 similarly to the blocking portion 5. An insulating layer 17 formed by integrally molding an organic insulating material such as an epoxy resin is provided around the vacuum valve 14 and the inorganic insulator 16.

  An operation mechanism 19 that opens and closes a pair of contacts in the vacuum valve 14 in the axial direction via an insulating operation rod 18 is provided on the movable side that is one main circuit end of the disconnecting portion 15. Further, the movable conductor 20 connected to the vacuum valve 14 is in sliding contact with the other end of the connecting conductor 13 in a direction orthogonal to the axial direction. At the other main circuit end of the disconnecting portion 15, a bus bar 21 molded with an organic insulating material for connecting to an adjacent board is provided.

  Note that the main circuit ends of the molded main circuit electrical devices such as the blocking portion 5, the disconnecting portion 15, the connection conductor 6, and the bus bar 21 are all interface connecting portions formed in a tapered shape, for example, not shown. The main circuit ends are connected to each other through a flexible insulator such as silicon rubber. Reference numeral 22 denotes a control room for controlling the blocking unit 5, the disconnecting unit 15, and the like.

  Of these main circuit electric devices, the blocking unit 5 is taken as an example, and the details thereof will be described with reference to FIG.

As shown in FIG. 2, the annular inorganic insulator 8 provided around the sealing fittings 7a and 7b has a bay-shaped curved portion 8a on the inner peripheral surface, and the outer peripheral surface has a predetermined curvature. It becomes the curvature part 8b. And it is being fixed to the sealing metal fittings 7a and 7b by the fixing | fixed part 8c provided in the curved part 8a. The insulating thickness t between the curved portion 8a and the curvature portion 8b, that is, the insulating thickness t of the inorganic insulator 8 is several mm or more having mechanical strength for self-supporting. Further, the insulating thickness t ₀ of the insulating layer 9 is less than t = t _0/2 .

As a result, the insulating thickness (= t ₀ −t) of the insulating layer 9 facing the inorganic insulator 8 becomes larger than the insulating thickness t of the inorganic insulator 8, so that the insulating layer 9 is the main part of the blocking portion 5. It becomes insulation. The same applies to other main circuit electric devices. The main insulating insulating layer 9 made of an organic insulating material is excellent in electrical and mechanical strength and can have a complicated shape.

  The relative dielectric constant ε of the insulating layer 9 is ε = 4, which is typical for an epoxy resin, whereas the relative dielectric constant of the inorganic insulator 8 is set to be larger than that of the epoxy resin. That is, for example, a general ε = 8 is used in the case of ceramic, and a general ε = 7 is used in the case of mica. Note that titanium oxide or the like may be mixed to make the relative dielectric constant larger than the above value. Furthermore, since ceramic is used for the insulating container of the vacuum valve 7, the inorganic insulator 8 is preferably made of the same kind of ceramic. Such an inorganic insulator 8 can be formed by pressurizing and thermoforming in a mold (not shown) and machining as required.

  As a result, when a partial discharge is generated from the tips of the sealing fittings 7a and 7b under the operating voltage of the switchgear, electrons accompanying the partial discharge reach the curved portion 8a of the inorganic insulator 8 and are trapped. And although partial discharge generate | occur | produces also in the inorganic insulator 8, insulation degradation does not occur easily on the performance of an inorganic insulating material. That is, the inorganic insulator 8 prevents the progress even if a partial discharge occurs. As a result, the insulating layer 9 serving as the main insulation is unlikely to cause insulation deterioration, and the partial discharge characteristics can be improved.

  Here, the sealing metal fittings 7a and 7b in the vacuum valve 7 have relatively acute angles at the ends, and are places where the electric field strength increases as compared with other parts. For this reason, the site | part where electric field intensity | strength rises like the sealing metal fittings 7a and 7b is defined as an electric field strength raise site | part.

  Note that, at the interface between the inorganic insulator 8 and the insulating layer 9, a potential difference is generated due to a difference in mutual insulation resistance. However, electric field relaxation at this interface can be achieved by setting the curvature of the curvature portion 8b to a predetermined magnitude. Moreover, since the relative dielectric constant of the inorganic insulator 8 is larger than that of the insulating layer 9, the potential sharing of the inorganic insulator 8 is reduced, and the electric field strength at the ends of the sealing fittings 7a and 7b can be suppressed.

  Furthermore, the insulating layer 9 and the inorganic insulator 8 are each an insulating material, and it is possible to obtain a stronger adhesive force than the conventional bonding between an insulating material and a metal material. If the surface of the inorganic insulator 8 is degreased or roughened, the adhesive strength can be further increased.

  According to the solid-insulated switchgear of the first embodiment, since the inorganic insulator 8 made of an inorganic insulating material is provided around the sealing fittings 7a and 7b of the vacuum valve 7 where the electric field strength is increased, the progress of partial discharge is achieved. Is blocked by the inorganic insulator 8, and the partial discharge characteristics of the insulating layer 9 made of an organic insulating material can be improved.

  Next, a solid insulated switchgear according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a configuration of a blocking portion used in the solid insulated switchgear according to the second embodiment of the present invention. The difference between the second embodiment and the first embodiment is the configuration of the inorganic insulator. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, for example, a conductive layer 23 coated with a conductive paint is provided on the inner surface of the curved portion 8 a of the inorganic insulator 8, and one of the metal fixing plates 24 is fixed to the conductive layer 23. The other is fixed to the sealing fittings 7a and 7b, respectively.

  Thereby, the conductive layer 23 and the sealing fittings 7a and 7b have the same potential. Under the operating voltage of the switchgear, a potential is directly applied to the inorganic insulator 8 and partial discharge is likely to occur. However, the inorganic insulator 8 is less likely to cause insulation deterioration, and as a result, the partial discharge characteristics of the insulating layer 9 are reduced. Can be improved. In addition, generation | occurrence | production of the partial discharge from the sealing metal fittings 7a and 7b is suppressed.

  According to the solid-insulated switchgear of the second embodiment, in addition to the same effects as those of the first embodiment, the occurrence of partial discharge from the sealing fittings 7a and 7b can be suppressed.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above-described embodiment, the inorganic insulators 8 and 16 are provided at both ends of the insulating containers of the vacuum valves 7 and 14, but the U-shaped corner portion or the like also in the connection conductor 6 or the like which is another main circuit electric device. The partial discharge characteristics can be improved by providing an inorganic insulator made of an inorganic insulating material at a portion where the electric field strength increases (field strength increasing portion).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a part of a configuration of a solid-insulated switchgear according to Embodiment 1 of the present invention. Sectional drawing which shows the structure of the interruption | blocking part used for the solid insulation switchgear which concerns on Example 1 of this invention. Sectional drawing which shows the structure of the interruption | blocking part used for the solid insulation switchgear which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Cable part 1b Opening-and-closing part 1c Bus-bar part 2 Cable head 3 Current transformer 4 Power cable 5 Breaking part 6 Connection conductor 7, 14 Vacuum valve 7a, 7b Sealing metal fittings 8, 16 Inorganic insulator 8a Curved part 8b Curvature part 8c Fixing parts 9, 17 Insulating layers 10, 18 Insulating operating rods 11, 19 Operating mechanisms 12, 20 Movable conductors 13 Connecting conductors 15 Disconnecting parts 21 Busbars 22 Control chambers 23 Conductive layers 24 Fixing plates

Claims (2)

A solid-insulated switchgear that constitutes a power supply system by combining main circuit electrical devices molded with an insulating material to form main insulation,
The main circuit electrical device is a vacuum valve, and a solid insulation switch comprising an inorganic insulator having a curved portion formed on an inner peripheral surface so as to surround an end of a sealing fitting of the vacuum valve gear. The solid insulation switchgear according to claim 1 , wherein a conductive layer is provided on a curved portion of the inorganic insulator so as to have the same potential as the sealing fitting .

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