KR800001404B1 - Electrical apparatus having an improved dielectric system - Google Patents

Abstract

An electrical apparatus, like a capacitor having an improved dielectrical system was described. The dielectric system has improved dielectrical properties and the polybutene is diodegradable to minimize the pollution of the atmosphere when the dielectric liquid is exposed to the atmosphere. Extended service life can be achieved by the addition of a cyclohexyl amine to the liquid dielectric.

Description

Capacitors with an Improved Dielectric System

1 is a perspective view of a capacitor of the present invention.

2 is a perspective view of a capacitor pack of the present invention.

3 is a diagram showing the flow of a mixture consisting of different ratios of mono-chlorodiphenyloxide and monochlorododecyl diphenyloxide.

4 is a diagram showing the initial discharge voltage at various temperatures of the paper-film capacitor of the present invention compared to the paper-film capacitor using diphenyl chlorinated as a penetrant.

The present invention relates to a capacitor having an improved dielectric system. The capacitor includes a layer formed by alternately overlapping a dielectric material formed by combining a metal foil and a polymer film and paper, wherein the paper is a monohalogenated diphenyl oxide and a monohalogenated alkyldiphenyl oxide (alkyl group having 1-20 A liquid dielectric composition comprising a mixture of carbon atoms). The capacitor of the present invention has improved corona properties, low dielectric loss and the liquid dielectric composition is essentially biochemically degraded.

In the structure of a capacitor, such as a power factor correction capacitor, the capacitor is formed of an alternating layer of metal foil and a solid dielectric material penetrated by a liquid dielectric.

Conventionally, kraft paper was used as a dielectric material. This type of capacitor has a relatively high dielectric loss, and its use is limited only to capacitors having a capacity of 100 kvar or less.

Combinations of paper and polymer films, such as polypropylene Philips, have also been used as dielectric layers in capacitors. Paper-film capacitors generally have lower dielectric losses and more certainty than paper-only capacitors, resulting in capacitors with larger kvar capacities. Although paper is limited in its use in all-day dielectric layers, this paper acts as a wicking material that increases the penetration of the liquid dielectric into the capacitor pack.

For many years, polychlorinated diphenyls have been used as liquid dielectrics in power factor correcting capacitors. And this liquid dielectric has made an effective dielectric system that allows for many improvements in capacitors. For example, the dose per kvar was reduced to a factor of eight, the dielectric loss was reduced to a factor of five or more, and the cost per kvar was reduced to a factor of about five. This improvement is at least partly achieved by using polychlorinated diphenyl as the liquid penetrant.

Although polydipinenels, such as trichlorodiphenyl, make an effective dielectric system for capacitors, polychlorinated diphenyls do not biochemically decompose, causing gaps or cracks in the capacitor vessels, or polychlorination when the capacitors are discarded. Diphenyl will remain as an environmental pollutant, and since it does not decompose as it is after several years, there is an ecological problem due to the use of the substance. In addition, polychlorinated diphenyl is known to accumulate in animals and to be toxic.

The present invention relates to a capacitor having an improved dielectric system. The capacitor includes a layer of alternating metal foil and a dielectric material composed of a polymer film and paper. The dielectric material is impregnated with a liquid dielectric composition consisting of a mixture of monohalogenated diphenyloxide and monohalogenated alkyldiphenyl oxide, wherein the alkyl group contains 1-20 carbon atoms in the molecule. Generally liquid dielectric compositions contain about 5-95% monohalogenated diphenyloxide and about 95-5% monohalogenated alkyldiphenyl oxide. The dielectric material may also contain 0.01-10% of the epoxide compound, which acts as a cleaning agent to neutralize chlorine ions or other degradable substances generated or separated from the impregnation or other material during operation of the capacitor.

The dielectric film of the polymeric material may be formed of a material such as polypropylene, polyethylene, polyester, or the like. The surface of the film and / or the contact surface of the metal foil may form irregular surfaces to have a storage effect of the liquid dielectric so that the liquid may be completely removed during the process. Can be penetrated.

The capacitor casing containing the solid dielectric layer during the capacitor process or assembly is preferably dried at temperatures below 60 ° C. under vacuum conditions and preferably at room temperature for a time sufficient to remove water vapor and other gases from inside the capacitor. The liquid dielectric is circulated under vacuum or stirred to remove gas from the liquid. After degassing the capacitor and the dielectric liquid separately, the liquid is introduced into the capacitor. When the capacitor is filled with the dielectric liquid, the vacuum of the liquid is removed while the temperature of the capacitor is kept below 60 ° C (room temperature is appropriate), or a pressure greater than atmospheric pressure is applied to the liquid. After infiltration, the vacuum is removed and the capacitor is sealed.

The capacitor of the present invention has a low dielectric loss and has excellent corona characteristics in a temperature range of -40 ° C to 90 ° C. Another advantage is that the liquid dielectric composition is less toxic to polychlorinated diphenyl, and therefore less likely to contaminate the environment in that it is less bioaccumulative and more prone to biochemical separation than polychlorinated diphenyl.

The dielectric system treated in accordance with the present invention to remove gases from the dielectric system can be operated without decomposing the polymer layer or liquid dielectric even under electrical stress at elevated temperatures up to 125 ° C. Due to increased stability at elevated temperatures, the dielectric system can be used in small, stable or special capacitors that can be used at operating temperatures up to 100 ° C as well as large power factor correction capacitors with typical operating temperatures (case temperature) -40 ° C to 70 ° C. Can be.

Another advantage is that the method of the present invention does not require post cure, which is often required for process technology.

By eliminating post-processing, which typically takes up to 72 hours, the overall time spent on the capacitor process is generally shortened, thereby reducing manufacturing costs.

Other objects and advantages of the present invention will be described below with reference to the present invention.

1 illustrates a typical capacitor comprising an outer case 1 having a wall 2, a bottom 3, and a cover 4.

The case 1 is sealed and a small hole 5 is made out of which the dielectric material is introduced into the case 1 during manufacture. In addition, a vacuum tube may be connected to the hole 5 for the vacuum drying of the capacitor at the time of manufacture. The pair of terminals 6 protrude through the cover and are insulated from the cover.

A series of capacitor packs 7 are arranged in the case 1, and as illustrated in FIG. 2, each capacitor pack has a metal foil 8 layer separated and wound by a dielectric layer 9, respectively. The electrodes 10 are connected to the thin layer 8 and the electrodes of the various packs are connected together in series so that they are finally connected to the terminals 6.

The thin layer 8 may be made of any electrical conductor material desired, and may generally be made of a metal material such as aluminum and the like. The layer 8 may be in the form of a flat sheet, or the surface may be irregular in a series of deformations formed by recessing one side of the foil and correspondingly raising the other side as described in US Pat. No. 3,746,953. have.

The solid dielectric layer 9 is made by combining a polymer film such as polypropylene, polyethylene, polyester or polycarbonate, and cellulose fiber material such as kraft paper, hygroscopic paper, hygroscopic wood fiber, and the like. The polymer film may be in the form of a strip having a smooth surface and may be in the form of a polymer strip, such as polypropylene, having a layer of fine polyolefin fibers that adhere to the surface as described in US Pat. No. 3,772,578.

Polymeric films generally contain up to 90% (by weight) of dielectric layers, in most cases consisting of 30-90% (by weight), with 70-85% (by weight) being preferred.

It is important that the surface of the weight film and / or the contact surface of the metal foil 8 cause the surface to be irregular or deformed so that the two contact surfaces continue to be in close contact with each other. Surface irregularities act as a wick or capillary of the lamp relative to the liquid dielectric, allowing liquid to fully penetrate the film 9 during the process.

Dielectric layer 9 penetrates into a liquid dielectric composition consisting of a mixture of monohalogenated diphenyloxide and monohalogenated alkyldiphenyl oxide, wherein the alkyl group contains 1-20 carbon atoms.

The monohalogenated diphenyloxide in the mixture is used in an amount of about 5-95% (weight) of the mixture corresponding to the monohalogenated alkyldiphenyloxide. In most cases monohalogenated diphenyl oxides use amounts of 10-70% (weight) of the mixture corresponding to monohalogenated alkyldiphenyloxides.

Of the two components, other halogens such as cancellation can also be used, but chlorine is the halogen choice. Halogen atoms are usually located in parawatches in each component, and about 80-100% of the halogen atoms are present in the para position and the remaining 0-20% are in the ortho position in the process of preparing these compounds. The alkyl group of the monohalogenated alkyldiphenyloxide preferably contains 3-16 carbon atoms, which may be straight chain or branched chain, and the particular position and branched chain number are not important to the present invention.

Specific examples of the dielectric composition used and used in the capacitor of the present invention are as follows.

Monobromo-diphenyloxide 50% and mono-chlorododecyl diphenyloxide 50%: monochlorodiphenyl oxide 30% and monochlorododecyldiphenyl oxide 70%: mono-chlorodiphenyl oxide 80% and mono- Chlorohexyldiphenyl oxide 20%: Mono-chlorodiphenyl oxide 40% and mono-chlorobutyldiphenyl oxide 60%: Mono-chlorodiphenyl oxide 20% and mono-chloropropyldiphenyl oxide 80%: Mono-chlorodi 35% phenyloxide and 65% mono-chlorohexyldiphenyloxide: 17% monochlorodiphenyloxide and 83% mono-chlorobutyldiphenyloxide, and the dielectric composition may contain 0.01-10% by weight of epoxide detergent And 0.2% -1.5% by weight. This epoxide detergent serves to neutralize the decomposition products that are liberated or generated from the liquid penetrant and other materials during operation of the capacitor. Neutralizers or detergents include 1,2-epoxy-3-phenoxypropane; Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate; 1-epoxyethyl-3,4-epoxy-cyclohexane; 3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexanecarboxylate; 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methyl-cyclohexanecarboxylate and mixtures thereof can be used. Epoxy compounds are effective at rapidly neutralizing decomposition products, thereby improving dielectric properties and extending capacitor life.

Mono-halogenated diphenyloxides can be prepared by conventional methods, in which the diphenyl oxide is composed of 0-halo diphenyl oxide and P-halodiphenyl oxide, as described in US Pat. No. 2,022,634. Halogenated by using an aluminum halide such as aluminum chloride, or other protonic acid to prepare the mixture.

Likewise mono-halogenated alkyldiphenyloxides can be prepared by known methods, in which the halogen diphenyloxide is treated with a small amount of aluminum chloride, as described in US Pat. No. 2,170,989, and then the mixture is subjected to reaction temperature. Alkyl halides or olefins are gradually introduced while maintaining the

No special process is required to mix the two components together, which can be mixed with one another at room temperature or at elevated temperatures. The mixture may also be prepared by an alkylation reaction, in which the alkylation reaction is terminated after reaction for a time sufficient to achieve the desired ratio of mono-halogenated alkyldiphenyl oxide and mono-halogenated diphenyloxide. Using this method to obtain lower alkyl alkylation results in some dialkylation.

To produce the capacitor of the present invention, the interior of the capacitor case containing the capacitor pack is first subjected to a pressure below vacuum or atmospheric pressure for a time sufficient to remove water vapor and other gases from the inside of the capacitor. The inside of the case 1 is vacuumed by a tube connected between the vacuum head and the hole 5. The vacuum is less than 100 microns, preferably less than 30 microns. Vacuum time can vary depending on the degree of vacuum, but usually vacuum drying for more than 40 hours.

In order to prevent molecular expansion of the polymer film, the temperature must be maintained at 60 ° C. or lower, and vacuum drying is preferably performed at a temperature of 43 ° C. or lower, such as room temperature. The polymer film is impregnated with a liquid dielectric, in which the liquid dielectric molecules move into the film and move from the high concentration to the low concentration until flatness is achieved. Since heating of the polymer film lowers the diffusion rate due to expansion of the molecular structure, heating the polymer film to a temperature of about 60 ° C. or more when drying the capacitor should be avoided.

The liquid dielectric is then vacuum dried to remove gas in the dielectric liquid. In order to perform the degassing treatment, a vacuum of 500 microns or less is used, and a vacuum of 50 microns or less is preferable. The liquid is vacuum dried for a time sufficient to remove the gas from the liquid. In order to promote outgassing, it is preferred to stir by circulating, stirring or mixing the liquid. The degassing time may vary depending on the viscosity of the liquid, the degree of vacuum, the form of agitation and other factors, and generally a vacuum drying treatment for at least 12 hours.

It is preferable to keep the liquid at room temperature during the vacuum drying treatment. You can heat it. The liquid from which the gas has been removed must be maintained at a temperature of 60 ° C. or lower, and preferably 43 ° C. or lower when introduced into the capacitor. The liquid dielectric from which the gas has been removed is introduced into the capacitor case 1 through a tube attached to the hole 5 while maintaining the vacuum. After filling the capacitor case, a vacuum of 100 microns or less, preferably 30 microns or less, is maintained for a sufficient time so that the solid dielectric layer is completely impregnated with the liquid dielectric. It takes more than 24 hours to saturate to optimal working conditions. During this period, the temperature of the solid dielectric layer 9 in the capacitor and the temperature of the liquid dielectric are kept at 60 ° C. or lower, preferably at 43 ° C. or lower, such as room temperature.

In addition, after filling, a positive pressure of 1-4 psig may be applied to the liquid dielectric in the capacitor to help the liquid dielectric penetrate the solid polymer layer. The pressure applied to the liquid dielectric is usually maintained for at least 30 minutes. In the manner of applying pressure to a liquid, although using a pressurized gas that is in direct contact with the liquid is undesirable because the gas is absorbed into the liquid and the absorbed gas can adversely affect the dielectric properties of the system, the liquid The method of applying pressure is not important.

If vacuum or pressurized after the infiltration or deposition period is over, remove them and seal the capacitor.

In the past, post-treatment operations were often used to heat sealed capacitors at temperatures of about 85 ° C. for up to 72 hours to improve penetration and provide better reliability. There is no need for post-treatment in the method of the present invention. Although no adverse effect occurs even if the post-treatment operation is performed in the present invention, post-treatment is not performed because post-treatment increases the overall process time. The process time is shortened without performing post-treatment work, and this time reduction is also important from the standpoint of productivity.

It has been found that the liquid dielectric compositions used in the capacitors of the present invention penetrate the polymer film faster than conventional dielectrics such as trichlorodiphenyl. This increase in penetration is related to the surface energy of the composition of the invention and at least in part depends on the relatively low viscosity of the composition. This increase in penetration rate can shorten the capacitor assembly time.

The liquid dielectric composition used in the electric bulb of the present invention has a relative dielectric constant that is generally lower than the relative dielectric constant of the polychlorinated diphenyl. For example, the relative dielectric constant of a composition consisting of 17% mono-chlorodiphenyloxide and 83% mono-chlorobutyldiphenyloxide is about 4.4, while the relative dielectric constant of trichlorodiphenyl for capacitor is about 5.9. Due to this fundamental difference in relative dielectric constant, it can be considered that the dielectric composition of the present invention is worse than polychlorinated diphenyl for capacitors. This is because the relative dielectric constant usually directly affects the capacitance, and the smaller the relative dielectric constant, the larger the volume of capacitor per kvar. Surprisingly, however, it has been found that the use of the dielectric composition of the present invention in combination with a paper-film solid dielectric results in little reduction in capacitance compared to similar capacitors penetrated with polychlorinated diphenyl.

On the other hand, a capacitor having a paper-only dielectric layer penetrated by the dielectric composition of the present invention works predictably in that the capacitance is reduced compared to a paper-only capacitor in which polychlorinated diphenyl is penetrated. Thus, the paper only capacitor penetrating the dielectric composition of the present invention should have about 20% greater than the paper only capacitor penetrating the polychlorinated diphenyl, or the paper only capacitor penetrating the polychlorinated diphenyl. In comparison, the electrical stress should be increased by about 10%.

It has been found that the relative dielectric properties of the polymer film slightly increase when the polymer film such as polypropylene is infiltrated with polychlorinated diphenyl such as trichlorodiphenyl. However, surprisingly, when the dielectric composition of the present invention is infiltrated, the relative dielectric constant of the polymer film is further increased, so that the relative dielectric constant of the dielectric composition of the present invention is only about 5.9 relative to the relative dielectric constant of 5.9 of the dichlorinated polyphenyl. Although it is about 4.4, the relative dielectric constant of the film infiltrating the dielectric composition of the present invention is actually slightly larger than the relative dielectric constant of the same film infiltrating polychlorinated diphenyl. The addition of 25-30% paper to the dielectric system using the liquid of the present invention only reduces the electrical capacity by about 1% compared to the capacitance obtained with the same system using polychlorinated diphenyls for capacitors. This is an unexpected result when compared to the expected reduction in capacitance of about 5-6% based on calculations involving the relative dielectric constant of the present invention. Thus, although the relative dielectric constant of the liquid of the present invention is generally lower than that of the polychlorinated diphenyl, the capacitance of the paper-film capacitor infiltrating the dielectric composition of the present invention is comparable to that of the capacitor using polychlorinated diphenyl. Do.

The liquid composition of the present invention, although monochlorinated, produces a stable dielectric system. Traditionally, stability has been known to increase with increasing chlorination, but the dielectric liquid compositions of the present invention have been found to make a stable system comparable to the stability of drichlorodiphenyl and tetrachlorodiphenyl. Is more easily biochemically decomposed, and has a significant advantage such as less toxicity and less accumulation in the living body.

Since the liquid dielectric composition of the present invention is completely biochemically decomposed, even if the composition is exposed to the environment by leaking, breaking, or abandoning the capacitor case, the liquid dielectric material is decomposed into non-toxic compounds and does not adversely affect the environment. . Polychlorinated diphenyls for capacitors, on the other hand, are environmentally resistant and are not readily biochemically decomposed.

Polychlorinated diphenyls have also been found to be toxic by accumulating in fish and animals. In contrast, the dielectric liquid of the present invention is less harmful to the environment because of less accumulation in living organisms and less toxicity to fish and mammals. For example, polyphenyldiphenyl chloride for capacitors accumulates 100-200 times or more in fish in vivo than a mixture of 17% monochlorodiphenyloxide and 83% (weight) monochlorodiphenyloxide of the present invention. Moreover, the acute oral toxicity of the polychlorinated diphenyls for the capacitor is about 10 times greater than the toxicity of the dielectric liquid composition of the present invention.

One of the important considerations in capacitor design is the partial initial discharge voltage (DIV). In the presence of partial discharge, it is important to disable the dielectric under partial discharge, conditions because the efficiency of the dielectric system is reduced and the lifetime is severely reduced.

The curve in FIG. 3 shows the pour point data of several mixtures of mono-chlorodiphenyloxide and mono-chlorododecyldiphenyloxide obtained under test conditions where the temperature was stabilized (at constant temperature) for several hours before measurement. As shown in this curve, the pour point of mono-chlorododecyldiphenyloxide alone is about 0 ° C and the crystal point of mono-chlorodiphenyloxide alone is about -81 ° C. Nevertheless, the pour point of the mixture of these two substances is much lower than the pour point of the individual components. For example, the pour point of a 50:50 mixture of two components is about -45 ° C, and the pour point of most mixtures is lower than -20 ° C.

It is desirable for the dielectric liquid to have a low pour point because the capacitor may be exposed to very low ambient temperatures in use. When the pour point is lowered by the mixture of the two components, the liquid dielectric does not crystallize above the full operating temperature of the capacitor and remains in the liquid state.

Since the dielectric liquid of the present invention has a lower pour point than that of capacitor-grade polychlorinated diphenyl, the capacitor of the present invention can be used at a temperature of -45 ° C, and -60 ° C depending on the mixing conditions of the components used in the liquid dielectric. It can be used even at a temperature.

Most dielectric systems have been found to have poor operating reliability at low temperatures. Dielectric systems that are allowed to stabilize at very low temperatures under electrical stress are susceptible to breakage too quickly, especially when operating the system at very low temperatures. Because of this, at low temperatures, the dielectric system must have a high loss rate. This is because at higher dielectric temperatures, which are more reliable, higher losses are the driving force for the capacitor. The dielectric loss characteristic of the dielectric system of the present invention satisfies the basic requirement of high loss rate at low temperature, thus improving the reliability of the capacitor. This feature provides a very good low temperature dielectric system with a low pour point of the dielectric liquid.

The discharge voltage of the film-paper capacitor of the present invention infiltrated with the dielectric liquid of the present invention is higher than that of similar capacitors using polychlorinated diphenyl in the normal operating temperature range (DIV). For comparison experiments, a set of test capacitors were fabricated using two electric grade polypropylene films of 0.0005 inches thick and one piece of kraft washer (74% polypropylene film and 26% kraft paper) with a thickness of 0.0005 inches and a dielectric layer. This flaky dielectric is located between 0.00025 inches of aluminum foil.

The test capacitor set is a polychlorinated diphenyl for capacitors (Arocolr 1016, a mixture of trichlorodiphenyl and tetrachlorodiphenyl mainly) and bis (3,4-epoxy-6-methylcyclohexyl-methyl) adipoxy additive as a cleaning agent. Infiltrate the pate with 0.5% by weight).

Another set of capacitors for testing is infiltrated into the dielectric liquid of the present invention, which is a mixture of 17% by weight monochlorodiphenyl oxide and 83% by weight monochlorobutydiphenyloxide and 0.5% of the epoxide additive above. All test capacitors are vacuum dried in an oven at 105 ° C. for 48 hours in a vacuum of 100 microns or less. In each case, the dielectric liquid is vacuum dried separately to 20 ° C. for 48 hours in a vacuum of 100 microns or less. The capacitor is cooled to 60 ° C. and the dielectric liquid is placed in the capacitor case and infiltrated at a temperature of 60 ° C. for 72 hours, at which time the liquid maintains a vacuum below 100 microns. After this penetration time is over, the vacuum of each sheet is removed and the capacitor is sealed.

All test capacitors are operated under conditions of electrical stress for 24 hours at 1,800 volts per mil at room temperature. After the end of the run time, the initial discharge voltage is determined at various temperatures from -45 ° C to 90 ° C. The results of this test are shown in FIG. 4 shows the initial discharge voltage values of the test film-paper capacitor infiltrating polychlorinated diphenyl and the test film-paper capacitor infiltrating the dielectric composition of the present invention as a function of temperature.

As can be seen in FIG. 4, the test capacitor of the present invention has a higher discharge voltage value than the test capacitor using polychlorinated diphenyl at normal operating temperature. Moreover, the characteristic dip shown at about −20 ° C. to 0 ° C. in the test capacitor using polychlorinated diphenyl is not shown in the test capacitor infiltrated into the dielectric composition of the present invention. The absence of this dip characteristic increases the safety zone, which results in higher electrical stress if the normal operating electrical stress is lower than the corona voltage, or vice versa, if the safety factor of the system remains about the same as when using polychlorinated diphenyl. It is important because it can be used.

This leads to the same kvar with a capacitor with a smaller volume.

This experiment illustrates that the capacitor of the present invention can be fabricated to have a discharge voltage greater than 1.5 kv / mil in all temperature ranges from -40 ° C to 90 ° C.

Film-paper capacitors of the invention are also stable under operating conditions. The stability and reliability of the system is shown in the data in the following table (I). In this experiment, the experimental capacitors used two 0,00075-inch-thick polypropylene films and one 0.00035-inch kraft washer as the dielectric material, and the laminar structure was sandwiched between 0.00025-inch thick aluminum foil. . This was made to penetrate into a mixture of 17% monochlorodiphenyl oxide and mono-chloro butyldiphenyloxide, with 0.5% epoxy additive (ERL-4289) used. Test film-paper capacitors are manufactured by the method described in the original discharge voltage-temperature test.

TABLE I

Table I shows the initial discharge voltage (kv / mil), the discharge voltage (kv / mil) after 192 hours of operation at 1,800V, and the discharge voltage (kv / mil) after 192 hours of operation at 2,100V.

As can be seen from Table I, operating under electrical stress improves the discharge voltage value, which is important because it shows that it actually improves the system without damaging the system when operating under voltage.

The capacitor fabricated by the present invention has good corona characteristics and low dielectric loss since it has a relatively high initial discharge voltage value in all operating ranges. The high initial discharge voltage increases the safety zone so that the voltage per mill is lower than the initial discharge voltage, or allows the increase in voltage per mill without reducing the safety zone.

Claims (1)

A capacitor comprising a pair of electrical conductors arranged separately from each other and adapted to provide a potential therebetween, and a capacitor constituting a dielectric system inserted between the electrical conductors, the dielectric system comprising a dielectric film composed of a polymer film and a cellulose fiber material. The dielectric composition is composed of a material and a dielectric solution composition injected into the dielectric material, and the dielectric composition constitutes a mixture of monohalogenated diphenyl oxide and a monohalogenated alkyldiphenyl oxide which is an alkyl group containing 1 to 20 carbon atoms in a molecule. And a capacitor having an improved dielectric system.

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