JPH0831684A - Flame-retardant capacitor - Google Patents

Abstract

PURPOSE:To provide a flame-retardant capacitor which has a small size and high performance by using either one or both of a plastic film and an insulating paper for a dielectric material and winding them to make a capacitor element and impregnating it with a perfluorocarbon liquid. CONSTITUTION:Aluminum foil is placed upon two sheets of roughened polypropylene films as an electrode to make a capacitor element by winding then. The capacitor element is impregnated with a perfluorocarbon liquid to make a capacitor. The perfluorocarbon which has the boiling point of not less than 80 deg.C; preferably 80 deg.C to 270 deg.C is used. Thereby, the capacitor characteristic is by no means inferior to that of the conventional oil-impregnated capacitor and the capacitor can show much better flame retardancy as compared with the conventional oil-impregnated capacitor.

Description

Detailed Description of the Invention

[0001]

This invention relates to flame retardant capacitors.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to install power receiving / transforming / distribution equipment underground under the influence of increasing power demand and rising land prices. In this case, of course, downsizing, high performance, and high reliability of the equipment are required, as well as prevention of sudden disasters,
In terms of suppression, it is also required to make the equipment nonflammable and flame retardant. The same applies to the capacitors used in the equipment.

Currently, SF6 is used as a flame-retardant capacitor.
A gas filled with an insulating gas such as gas is known. That is, the capacitor element is installed in a case and is filled with an insulating gas. However, such a gas-insulated capacitor has a drawback that the device has a large volume because of its low withstand voltage as a characteristic of the gas.

There is also known a flame-retardant capacitor impregnated with an insulating liquid, for example, a phosphoric acid ester type insulating oil, but this type of insulating oil is extremely difficult to process in the capacitor manufacturing process. Not only does the manufacturing process become complicated, but tan δ is large in terms of performance. On the other hand, a capacitor impregnated with an insulating oil such as mineral oil or synthetic oil is flammable and does not satisfy flame retardant performance.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small size, high performance flame retardant capacitor.

[0006]

According to the present invention, one or both of a plastic film and insulating paper is used as a dielectric, and a capacitor element formed by winding the dielectric is impregnated with a perfluorocarbon liquid having a boiling point of 80 ° C. or higher. It is characterized by

[0007]

FUNCTION The perfluorocarbon has a hydrocarbon structure in which all the hydrogen moieties directly bonded to carbon are replaced with fluorine, and includes those in which other atoms are bonded in the molecule. And its boiling point is 80 ° C or higher, preferably 80 ° C to 270.
Use the one at ℃. Although heat treatment is performed in the process of manufacturing the capacitor, the treatment temperature is lower than about 80 ° C. Therefore, it is not preferable that the impregnated perfluorocarbon liquid boils in the treatment step. Further, the perfluorocarbon liquid is at least −
What is in a liquid state at 20 ° C to 80 ° C is used.
This is because the operating temperature of the capacitor is usually -20 ° C to 80 ° C.

The performance of the perfluorocarbon liquid is shown in Table 1. For comparison, synthetic oil 1-phenyl-1-
The performances of (dimethylphenyl) ethane (hereinafter simply referred to as PXE) and mineral oil are shown together. As can be understood from this, the perfluorocarbon liquid has excellent insulation performance as compared with synthetic oil and mineral oil, and its low viscosity and surface tension have excellent permeability between dielectric layers. Means that.

[0009]

[Table 1]

Table 2 shows a polypropylene film used as a dielectric, a perfluorocarbon liquid, a synthetic oil,
It shows the swelling performance for mineral oil. As can be understood from the following, polypropylene film swells 6% and 9% against synthetic oil and mineral oil,
In the perfluorocarbon liquid, the polypropylene film did not undergo any dimensional change due to swelling.

[0011]

[Table 2]

[0012]

EXAMPLES Examples of the present invention will be described below. Thickness 20μ
Aluminum foil was superposed as an electrode on two roughened polypropylene films of m, and this was wound to form a capacitor element. This capacitor element was impregnated with a perfluorocarbon liquid to manufacture a 10 μF capacitor. For comparison, the same capacitor element as in the example was impregnated with PXE to manufacture a 10 μF capacitor. Table 3 shows the characteristics of both capacitors.

[0013]

[Table 3]

As can be seen from Table 3, the capacitor according to the invention has a lower tan δ than that of the comparative example,
Further, the amount of discharge charge at the start of partial discharge is small. A small discharge charge amount means that the possibility of dielectric breakdown is low.

Next, the flame retardancy of both capacitors was examined. That is, dielectric breakdown is caused in advance in the capacitor element, a hole is opened in the case accommodating the capacitor element to facilitate ignition, and then a short-circuit voltage of 6000 V and 6000 A and a short-circuit current of 5 are applied to the capacitor.
It was supplied for 0 msec.

As a result, in the condenser of the embodiment, only white smoke was ejected after the momentary flame was generated, and the combustion was not continued. This proves that self-extinguishing was performed. Moreover, the bushing was not damaged at all. The case was slightly deformed. On the other hand, in the capacitor of the comparative example, after a large arc discharge, a large-scale flame was ejected and the combustion continued. Also, the bushing was damaged and the case was greatly deformed.

In the above example, a polypropylene film is used as a dielectric, but instead of this, another plastic film or an insulating paper is used, and a plastic film such as a polypropylene film and an insulating paper are combined. It has been confirmed that the same capacitor performance and flame retardant performance are exhibited even when used as a metallized film.

[0018]

As described above, according to the present invention, the capacitor characteristics are not inferior to the conventional oil-immersed capacitor, and moreover, the flame-retardant property is superior to the conventional oil-immersed capacitor. There is an effect that can be.

Claims (1)

[Claims] 1. A capacitor element formed by winding one or both of a plastic film and insulating paper, or a metallized film as a dielectric, and impregnating the capacitor element with a perfluorocarbon liquid having a boiling point of 80 ° C. or higher. Flammable capacitors.