JPH0236518A - Oil-impregnated capacitor - Google Patents

Abstract

PURPOSE:To counteract thermal effect and lengthen the life of a capacitor by a method wherein an insulating power, two sheets of dielectrics comprising a sheet of paper and a plastic film, and a foil electrode are alternately arranged while a lead piece is inserted between the plastic film and the foil electrode and is wound around and the wound element is impregnated with insulating oil. CONSTITUTION:An insulating paper 11 10mum thick, a polypropylene film 22mum thick and an aluminum foil electrode 13 6mum thick are laminated in this order, lead piece 14 50mum thick is inserted between the polypropylene film 12 and the foil electrode 13 and then an element winding around the polypropylene film 12, the insulating film 11 and the foil electrode 13 is impregnated with an insulating oil to manufacture a capacitor 1muF. When this capacitor is compared with another capacitor 1muF comprising respective materials in the same thickness, a lead piece 4 inserted into an insulating paper 1 and an aluminum foil electrode 3 which is wound around and impregnated with insulating oil, the dielectric strength characteristic of the former capacitor is superior to that of the latter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an oil-immersed capacitor using foil electrodes and paper and plastic films as dielectrics.

BACKGROUND OF THE INVENTION A conventional capacitor has two dielectric foil electrodes 3, a plastic film 2 and a paper 1, arranged alternately as shown in FIG.
The lead piece 4 was inserted between the paper 1 and the foil electrode 30 and wound, and the wound element was placed in a case and impregnated with oil. Recently, as a result of studies to improve corona properties, there is a trend towards lower viscosity of impregnating oil.

Problems to be Solved by the Invention However, by reducing the viscosity of the impregnating oil, the impregnating oil penetrates between the lead piece 4 and the foil electrode 3, and a thin oil layer is formed between the lead piece 4 and the foil electrode 3. Electrical discharge may occur between this oil layer. There is a drawback that heat is generated locally due to direct exposure, and the plastic film 2 in contact with the foil electrode 1 in the discharge section is damaged by the heat, significantly shortening the life of the capacitor.

Means for Solving the Problems The present invention consists of alternately arranging two dielectrics made of paper and a plastic film and a foil Kli, inserting a lead piece between the plastic film and the foil ``ti'' and winding it around the wound element. It is found in capacitors impregnated with oil.

Function: Even if a discharge occurs between the lead piece and the foil electrode in the capacitor having the structure of the present invention, since the dielectric material in contact with the foil electrode in the discharge part is paper, the thermal effect is alleviated and the life of the capacitor is extended. extends to a large width, making it a highly reliable capacitor.

Example Examples of the present invention will be described below.

In the embodiment shown in FIGS. 1 and 2, an insulating paper 11 with a thickness of 10 μm, a polypropylene film 12 with a thickness of 22 μm, and an aluminum chamber @ 13 with a thickness of 6 μm are laminated in this order, and a lead piece 14 with a thickness of 50 μm is laminated. Insulating paper 11. Foil electrode 13
The element is wound as shown in Figure 2 and impregnated with insulating oil to
A capacitor of F was obtained. For comparison, in the structure shown in FIG. 4, the thickness of each material is the same as in the above embodiment, and lead piece 4 is used.
was inserted between the insulating paper 1 and the aluminum foil electrode 3 and wound to obtain a 1 μF conventional capacitor impregnated with impregnating oil.

10 units each of both capacitors ■ and @ at 60℃, AC26
Figure 3 shows the breakdown time as a result of applying current at 00V.

From FIG. 3, it can be seen that the capacitor (■) of the present invention has better withstand voltage characteristics than the conventional capacitor (◎). All the broken parts of the conventional capacitor @ are the aluminum foil electrodes 3
and the polypropylene film 1 on the back of the foil electrode 3 at the contact portion of the lead piece 4.

This is because, as shown in Fig. 5, in a conventional capacitor @, impregnated oil enters between the aluminum foil electrode 3 and the lead piece 4, and when a discharge occurs there (part A), the aluminum foil electrode 3 Since the thickness is thinner than the piece 4, the heat during discharge in the A part is directly conducted to the back surface of the aluminum foil-4Wi3, and the B part of the polypropylene film 2 is locally heated. This is because the rE resistance of part B rapidly decreases when it is locally heated under voltage application.

In the case of the present invention, since the back side of the aluminum foil 3 of the discharge part A is paper 1, the influence of heat is small, and it is considered that the withstand voltage is not significantly reduced due to heat.

In this example, a polypropylene film was used as the plastic film, but similar results were obtained with other films such as polyethylene terephthalate, polyethylene, and polycarbonate.

Effects of the Invention The capacitor with a dielectric, foil electrode, and lead piece configuration according to the present invention can reduce the effects of heat generated between the foil electrode and the lead piece and during discharge, and can provide a capacitor with excellent voltage resistance. .

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of a capacitor showing an embodiment of the present invention, Fig. 2 is an exploded perspective view of the same capacitor, and Fig. 3 shows the current-carrying time and survival rate of each capacitor in the embodiment of the present invention and the conventional example. A characteristic diagram showing the relationship, FIG. 4 is a schematic sectional view of a conventional capacitor, and FIG. 6 is an enlarged sectional view of the same essential part. FIG. 6 shows the relationship between the insertion position of the lead piece and the residual withstand voltage. 11... Insulating paper, 12... Polypropylene film, 13... Foil electrode, 14...
...Lead piece. Name of agent: Patent attorney Shigetaka Awano and one other person Atsushi
1 Figure 2

Claims (1)

[Claims] An oil-immersed capacitor is made by sequentially laminating and winding paper, a plastic film, and a foil electrode, and a lead piece is inserted between the plastic film and the foil electrode and impregnated with oil.