JPH039208Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a capacitor core for capacitor bushings.

(Prior technology) This type of capacitor core is made by winding a fibrous insulating sheet such as kraft paper into a cylindrical shape with an electrode sheet such as metal foil interposed between the layers, and then impregnating the main body with a thermosetting synthetic resin. It is well known that resin-impregnated types are mainly used because they have excellent electrical properties including partial discharge characteristics. (For example, p. 321 of "Insulator" published by the Institute of Electrical Engineers of Japan, June 15, 1983) (Problem that the invention aims to solve) However, in the conventional capacitor core of this type, during the curing of the impregnated resin during the manufacturing process, Cracks occur between the insulating sheet layer and the electrode sheet layer due to differences in shrinkage rate and elastic modulus in the radial tangential direction and axial direction of the insulating sheet wound into a cylindrical shape, making it impossible to obtain the desired characteristics. . Therefore, we have adopted methods of forcibly suppressing the occurrence of cracks by applying crepe processing to the insulating sheet in advance to reduce the difference in shrinkage rate and elastic modulus, or by curing the impregnated resin under high pressure. However, even with the former method, it is not possible to completely prevent cracks when manufacturing a thick and long core with a rated voltage exceeding 287.5KV.
In addition, the latter method requires a huge investment in equipment, and since high-pressure gas is used, it is subject to safety measures and has various problems, such as high costs.

(Means for solving the problems) The present invention aims at a resin-impregnated type capacitor core that solves the above-mentioned problems.
In the case of a resin-impregnated type capacitor core in which a fibrous insulating sheet is wrapped in a cylindrical shape with an electrode sheet interposed between the layers and impregnated with a thermosetting synthetic resin, the main body is equipped with a central conductor. If the main body does not have a central conductor, only the innermost and outermost electrode sheet layers of the main body are provided with a large number of through holes only in the outermost electrode sheet layer. It is characterized in that the insulating sheet layers on both sides of the sheet layer are interconnected with a thermosetting synthetic resin that fills the through holes during resin impregnation.

(Function) With this structure, the insulating sheet layers on both sides sandwiching the electrode sheet layer in the required part of the cylindrical main body, that is, the part where cracks are likely to occur when the impregnated resin hardens, are connected to the electrode. Since the electrode sheet layer is connected with a hardened thermosetting synthetic resin that fills a large number of through holes provided in the sheet layer, the electrode sheet layer is incorporated between both insulating sheet layers. Therefore, even if the impregnated resin is cured under normal pressure to produce a thick and long product, there will be almost no cracks between the insulating sheet layer and the electrode sheet layer, and it will have excellent electrical properties. Become.

(Example) Next, the present invention will be explained in detail using a capacitor core for a resin-impregnated paper capacitor bushing for penetration into oil as an example. The main body is a fibrous insulating sheet overlaid with aluminum foil or other electrode sheets wrapped around a central conductor 2, and the electrode sheet layer 3 on the outside of the main body 1 is made of aluminum foil with a wall thickness of 20 μm and a diameter of 20 μm. A large number of circular through holes 4 each having a diameter of 5 mm are arranged uniformly with an interval of 20 mm between them, except for the peripheral portion,
The electrode sheet layer 5 on the inside is the same as the electrode sheet layer 3.
The wall thickness and material are the same, but they are made of non-porous aluminum foil. And this subject 1
is impregnated and cured with a thermosetting synthetic resin such as epoxy resin by a conventional method, but the insulating sheet layers 6, 6 on both sides of the electrode sheet layer 3 in which the through holes 4 are arranged are impregnated with resin. They are interconnected by a thermosetting synthetic resin 7 which is cured by filling the through hole 4. Note that the thickness and material of the electrode sheet layer 3 or the shape, size, spacing, etc. of the through holes 4 are not particularly limited, and for example, the shape of the through holes 4 may be oval, rectangular, or any other shape. However, when using a thin aluminum foil with a wall thickness of 10 to 50 μm to prevent cracks caused by shrinkage during curing of the resin-impregnated insulating sheet as in the above example, it is necessary to To prevent the aluminum foil from deforming or tearing, and to facilitate the flow of the thermosetting synthetic resin during resin impregnation, to prevent partial discharge due to electric field concentration on the inner surface of the through hole after the resin has hardened. In order to prevent
The distance between the through holes 4 and 4 is set to 5mm as a small hole.
It is generally about 50 mm, preferably about 5 to 20 mm. Note that the size and wall thickness of the main body 1 are not limited, but experiments have shown that even in long objects with an outer diameter of 300 mm and a wall thickness of 100 mm or more that exceed the rated voltage of 287.5 KV, insulating sheets can be used. It has been confirmed that no cracks occur between the layer 6 and the electrode sheet layer 3, and this effect is remarkable in this kind of long material. The illustrated embodiment is equipped with a center conductor 2, and the part where cracks are likely to occur during curing is the interface between the outermost electrode sheet layer 3 and the insulating sheet layer 6 in contact with it. A through hole 4 is provided only in the electrode sheet 3, and an insulating sheet layer 6 on both sides of the electrode sheet layer 3 is formed by a thermosetting synthetic resin 7 which is cured by filling the through hole 4.
6, but if the main body does not have a central conductor, the part where cracks are likely to occur during curing will also be at the interface between the innermost electrode sheet layer and the insulating sheet layer in contact with it. Therefore, through holes are provided in both the innermost and outermost electrode sheets, and the insulating sheet layers on both sides of each electrode sheet layer are connected using a thermosetting synthetic resin that fills the through holes. Even if this is a problem, the electrode sheet layer 3 provided with the through holes 4 may be used only in the portions of the main body 1 where cracks are likely to occur when the impregnated resin is cured. In addition to the above-mentioned metal foil, the electrode sheet layer may be formed by depositing metal on the surface of a conductive sheet made of carbon fiber or an insulating sheet such as glass cloth to form a conductive thin layer. effect can be obtained.

(Effects of the Invention) As is clear from the above description, the present invention provides a resin-impregnated type capacitor core in which an insulating sheet layer sandwiching an electrode sheet layer in a portion where cracks are likely to occur when the impregnated resin is cured is used. A special insulating sheet is used because the electrode sheet layer is incorporated into the insulating sheet layers on both sides by connecting the through holes provided in the sheet layer with the thermosetting synthetic resin filled during resin impregnation. It is possible to provide thick and long capacitor cores with excellent crack-free electrical characteristics without having to harden the impregnated resin under high pressure. It has the advantage of being able to reduce costs because it can be manufactured easily without any restrictions, and it has great practical value as it solves the problems of conventional resin-impregnated type capacitor cores.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the main part. DESCRIPTION OF SYMBOLS 1... Main body, 2... Center conductor, 3... Electrode sheet layer with through holes, 4... Through holes, 5... Non-porous electrode sheet layer, 6... Insulating sheet layer, 7... Thermosetting synthetic resin that fills the holes.

Claims (1)

[Scope of utility model registration request] In the case of a resin-impregnated type capacitor core in which a fibrous insulating sheet is wrapped in a cylindrical shape with an electrode sheet interposed between the layers and impregnated with a thermosetting synthetic resin, the main body is equipped with a central conductor. Only the outermost electrode sheet layer,
If the main body does not have a central conductor, a large number of through holes are provided only in the innermost and outermost electrode sheet layers of the main body to connect the insulating sheet layers on both sides of the electrode sheet layer. 1. A capacitor core characterized in that the through holes are interconnected with a thermosetting synthetic resin that fills the holes during resin impregnation.