JPS6342405B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oil-immersed capacitor, particularly an oil-immersed capacitor that uses only polypropylene film as a dielectric. Conventionally, oil-immersed capacitors impregnated with insulating oil have used capacitor paper as the dielectric material, but with the recent development of plastic film,
This plastic film came to be used as a dielectric material for capacitors, and polypropylene film, which had particularly excellent electrical properties, was often used in combination with capacitor paper as a dielectric material for capacitors. In order to effectively utilize the excellent properties of polypropylene film (hereinafter referred to as PP film), it is natural to use only PP film as a dielectric material, but PP film has a higher surface resistance than capacitor paper. It has the fatal disadvantages of being smooth, making it difficult for insulating oil to impregnate, easily forming voids between film layers, and having a low corona discharge starting voltage. I was making up for it. The present invention eliminates the above-mentioned drawbacks, improves impregnation using only PP film as a dielectric, and provides an excellent oil-immersed capacitor that takes advantage of the characteristics of PP film. Hereinafter, a comparative example shown in FIGS. 1 and 2 and an example according to the present invention will be described. Reference numeral 1 is an electrode, which is a normal aluminum foil.When rolling, two sheets are overlapped and passed through a rolling roll, so after rolling, the side that contacts the rolling roll is a smooth surface, and the side where aluminum foils are in contact with each other is a smooth surface. It forms a slightly rough surface. Reference numeral 3 denotes an electrode, which is formed by mechanically embossing the aluminum foil to form irregularities. As for the shape to be embossed, it is preferable that the embossed foil has a thickness of 10 to 16 μm and a mesh shape with a pitch of 100 to 250 meshes.
2 is a PP film, and the surface of this PP film is made rough by mechanically or chemically processing one or both sides (first
(The figure and FIG. 2 show examples in which only one side is roughened). The degree of surface roughening is the micrometer thickness (referred to as t _M ) of a 100 mm x 300 mm PP film sheet.
It is preferable that the space factor (referred to as Sf) determined by the following formula from the thickness (referred to as _tW ) by the gravimetric method is about 2% or more. Sf = t _M - t _W / t _W × 100 (%) As shown in Figures 1 and 2, the above PP film 2 and electrodes 1 or 3 are stacked alternately and wound to form a capacitor element. do. The present invention uses PP film as a dielectric material in order to effectively utilize the excellent properties of PP film.
Moreover, it is an object of the present invention to provide an oil-immersed capacitor that can be easily and sufficiently impregnated with insulating oil and has excellent corona characteristics. Therefore, embossed electrodes and roughened PP films are the best as oil channels for insulating oil impregnation. Next, an experimental example will be explained.

[Table] The above table shows the corona discharge start voltage and corona discharge extinguishing voltage of 8 types of samples made using two 18μ thick PP films and 7μ thick aluminum foil to fabricate a 2μF capacitor at 20℃. The results are shown below. In the insulating oil shown in the above table, alkyldiphenylthane was used as the diarylalkane, soft dodecylbenzene was used as the alkylbenzene, and diisopropylnaphthalene was used as the alkylnaphthalene. As is clear from the table above, the oil-immersed capacitor of the present invention (Sample D), in which a capacitor element constructed using a roughened PP film and embossed electrodes is impregnated with alkyl diphenylethane, is different from other capacitors (Samples A to C). . In the above example, a case was shown in which alkyldiphenylethane was used as the diarylalkane, but similar effects were obtained using other diarylalkane hydrocarbon compounds. The oil-immersed capacitor of the present invention can obtain a high corona discharge start voltage and corona discharge extinction voltage using only the PP film dielectric, so there is no need to use capacitor paper in conjunction with the conventional method, so the dielectric loss is small and the product is It has effects such as miniaturization and simplification of drying treatment during the manufacturing process, and has great industrial and practical value.

[Brief explanation of the drawing]

1 and 2 are oil-immersed capacitors using a roughened polypropylene film, FIG. 1 is a sectional view of a capacitor element structure for comparison, and FIG. 2 is a sectional view of a capacitor element structure according to the present invention. It is. 1: Electrode (normal metal foil), 2: Roughened polypropylene film, 3: Embossed electrode (embossed metal foil).

Claims (1)

[Claims] 1 The space factor is 2% by roughening the surface.
A capacitor made by alternately laminating and winding a dielectric material made of multiple sheets of polypropylene film as described above, and electrodes made of aluminum foil with a thickness of 10 to 16 μm embossed in a mesh pattern of 100 to 250 mesh. An oil-immersed capacitor characterized in that the element is impregnated with a diarylalkane hydrocarbon compound (diarylalkane) as an insulating oil.