JPS607007A - Oil-immersed capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides an oil-immersed capacitor with improved characteristics, higher withstand voltage, and higher reliability for use in high voltage applications, power applications, electrical equipment applications, electronic communication applications, etc. It is related to.

Conventional structure and its problems Conventionally, in oil-immersed capacitors having a dielectric material of plastic film, insulating paper, or a combination of these,
As insulating oils to replace chlorinated phenyl oils, ester oils such as phthalate esters and fatty acid esters, and various oils such as diallylalkane and alkylbenzene have been studied and put into practical use as impregnating oils. Also, some mixed oils of these have been proposed as impregnating oils for capacitors. The reason why so much research has been conducted and several proposals have been made is that it is extremely important industrially to realize all oil-immersed capacitors that have better capacitor characteristics, higher voltage resistance, and higher reliability. There are many things that can be mentioned.

Furthermore, with regard to additives for impregnated oil, proposals have been made to improve the reliability of oil-immersed capacitors by incorporating various additives.
Publication No. 39 1% Publication No. 1983-35999, Japanese Patent Application Publication No. 1983
4-15168, etc., many proposals have been made for epoxy stabilizers, phenol stabilizers, phosphite stabilizers, and other antioxidants and deterioration inhibitors. However, these additives capture all of the chlorine and water in the impregnating oil, or the decomposition products of the impregnating oil.
This has the great effect of completely suppressing the acceleration of deterioration of the impregnated insulating oil and dielectric during long-term life and actual use, and improving reliability over long periods of use, but the dielectric loss value of oil-immersed capacitors (hereinafter referred to as tan δ) itself is not significantly improved; on the contrary, if the total amount of contamination increases, which increases the probability of capturing chlorine, water, or decomposition products, it has the disadvantage that the tan δ of the oil-immersed capacitor deteriorates. However, the reliability of quality maintenance during long-term use is extremely improved due to the capture effect of decomposition products in the impregnated oil, but it is also possible to completely suppress heat generation due to tanδ loss of oil-immersed capacitors under high temperature and high voltage, and to prevent thermal breakdown. Purpose of the Invention The present invention aims to improve the tan δ of an oil-immersed capacitor equipped with a plastic film, insulating paper, or a composite thereof as a dielectric material under high temperature and high voltage conditions. This has been improved more than ever before, suppressing thermal damage when high voltage is applied, and completely increasing the partial discharge starting voltage of oil-immersed capacitors in low temperature ranges. The overall objective is to obtain an oil-immersed capacitor with extremely high withstand voltage and high reliability.

Structure of the Invention As a structure for this purpose, the present invention provides plastic film or insulating paper. Alternatively, a capacitor element having a composite dielectric material is impregnated with a mixed oil of phthalate ester and alkylbenzene in which a silica/Kublink agent is mixed.

The functional groups described in the examples are silicon compounds with different reactivities. This silane coupling agent can usually be expressed by the general formula %. Here, X represents a hydrolyzable group bonded to 81 atoms, and is an alkoxy group.

Typical examples include acyloxy groups (especially acetoxy groups), halogens (chloro in %), etc. 0 or Y represents various organic functional groups, such as vinyl groups, phenolic groups, mercapto groups, chloro groups, beluoxy 7 Typical examples include organic functional groups such as ureido groups and ureido groups, which are bonded to Si atoms directly or via organic groups Ri.Specific examples of silane coupling agents include γ-meth Acryloxypropyltrimethoxysilane, γ-glycidoxyglobyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-
Chloroglopyltrimethoxy 7rane, γ-mercagutogropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane.

Examples include γ-chloropropylmethyldimethoxysilane and γ-mercaptoglobilmethyldimethoxysilane.

The present inventors conducted research with the aim of improving the tan δ characteristics of oil-immersed capacitors impregnated with insulating oil and improving partial discharge inception voltage in low temperature ranges, and conducted research on phthalic acid mixed with the silane coupling agent. Mixed oil of ester and alkylbenzene? By impregnating the oil, the tan δ of the oil-immersed capacitor was significantly improved compared to the conventional one, and the partial discharge onset voltage in the low temperature range was also improved.

The amount of the silane coupling agent mixed varies depending on the rating and shape of the oil-immersed capacitor, the thickness of the dielectric used, etc., but is generally preferably 0.1 to 10% by weight. This is because if it is less than 0.1% by weight, the above-mentioned tan δ characteristics will not be improved much, and if it exceeds 10% by weight, the insulation resistance of the oil-immersed capacitor tends to decrease. In addition, considering economic efficiency, this silane coupling agent is extremely expensive, and it is desired that the amount thereof be as small as possible.

When the oil-immersed capacitor of the present invention is to be fully put into practical use, it is economical to use a silane coupling agent that is highly effective even when mixed in a small amount.

An example of a silane coupling agent that gives particularly good results is γ-methacryloxyglopyltrimethoxysilane.

The phthalate ester used in the present invention is generally represented by , and there are many molecular structures depending on the number of n or the presence or absence of branching, and many are produced industrially. Typically, di-2-ethylhexyl phthalate, diisodecyl phthalate, dibutyl phthalate, diobutyl phthalate, and dibutyl phthalate.

Dihectyl phthalate, dithychlorohexyl phthalate.

Examples include ditridecyl phthalate and butylbenzyl phthalate.

The alkylbenzene used in the present invention is generally represented by the following, and there are several types of molecular structures depending on the number of n or the presence or absence of branching, and it is widely used as various insulating oils.

Next, a concrete example of the present invention will be described. A polyglopyrene film with a thickness of 08 μm is used as a total dielectric material, and a capacitor element in which metallized paper electrodes are layered and wound is coated with An oil-immersed capacitor was fabricated by impregnating it with a mixed oil of phthalate ester and alkylbenzene, and the tan δ and effective dielectric constant of the oil-immersed capacitor at 100℃, as well as the partial discharge inception voltage at -30''C were measured.The results were as follows. are shown in Table 1 below.

Below is the blank space in Table 1. For the phthalate ester, di-2-ethylhexyl phthalate is used, and for the alkylbenzene, n = 1 to 9 in the above-mentioned membrane structural formula.
A mixture of these was used. The partial discharge inception voltage at -3oC was set to the full partial discharge inception voltage at which the occurrence of a discharge of 10oO picocuilons or more was observed.

As is clear from the results in the above table, tan δ is significantly improved by adding a silane coupling agent, and when a silane coupling agent is added to a mixed oil of phthalate ester and alkylbenzene, ,
It can be seen that an oil-immersed capacitor with an improved partial discharge inception voltage at -30°C and a good tan δ can be obtained. In addition, the effective dielectric constant in Table 1 is the composite dielectric constant of the polypropylene film and impregnated oil that form the capacitance when a wound capacitor element is impregnated with insulating oil to form an oil-immersed capacitor. It is measured as an effective dielectric constant since capacitance is determined, and the larger the effective dielectric constant, the smaller the oil-immersed CO7 will be.

Therefore, the lower the mixing ratio of alkylbenzene, the more economical the oil-immersed capacitor will be, but it is preferable to completely adjust the mixing ratio depending on the rating and application depending on the partial discharge inception voltage of -30°C.

Further, these oil-immersed capacitors were continuously energized and the ambient temperature was repeatedly changed from -30° C. to 100° C., and a continuous energizing cold/heat cycle test was conducted. The results are shown in the following @2 table.

Table 2 The thermal cycle was set at -30° C. for 2 hours and at 100° C. for 2 hours, and this cycle was repeated to determine the number of cycles at which the oil-immersed capacitor broke down as the breaking cycle. Second
From the results shown in the table, the oil-immersed capacitor impregnated with the mixed oil of phthalate ester and alkylbenzene in which the silane coupling agent of the present invention is fully added has an extremely long pressure life in an atmosphere with repeated cycles of low and high temperatures. I know it's expensive.

Almost similar results were obtained with other types of silane coupling agents or other phthalate esters. Similar results were also obtained when a capacitor element was impregnated with an insulating paper or other film alone or a mixture of these dielectrics as a dielectric.

Effects of the Invention According to the present invention, the tan δ in the high temperature range of an oil-immersed capacitor having a glass film, insulating paper, or a composite dielectric of these can be significantly improved, and the total partial discharge inception voltage in the low temperature range can be made extremely high. This makes it possible to create an extremely innovative high-voltage oil-immersed capacitor element that completely prevents damage caused by partial discharge in low-temperature ranges and thermal damage caused by heat generation due to tan δ in high-temperature ranges. It is something.

Claims (1)

[Claims] An oil-immersed capacitor in which a capacitor element entirely composed of plastic film, insulating paper, or a dielectric composite of these is impregnated with a mixed oil of phthalate and alkylbenzene mixed with a silane coupling agent.