Claims
- 1. In a method of preparing an electrical capacitor including the steps comprising:
- (i) rolling a metal foil electrode together with a dielectric material in layers to provide capacitor elements,
- (ii) disposing said elements in a container and
- (iii) impregnating said elements with an electrical insulating oil which can be used at temperatures as low as -40.degree. C., the improvement which comprises:
- employing as said electrical insulating oil an oil composition comprising 45% by weight or more of at least 2 members selected from the group consisting of the following 6 components and the remainder of non-condensed bicyclic aromatic hydrocarbons having not more than 17 carbon atoms except said 6 components:
- (a) m-ethylbiphenyl,
- (b) p-ethylbiphenyl,
- (c) o-benzyltoluene,
- (d) m-benzyltoluene,
- (e) p-benzyltoluene, and
- (f) 1,1-diphenylethane and is characterized in that, when the temperature of said composition is -40.degree. C.,
- (I) the total quantity of solid phase obtained by calculating according to the following solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of said composition, and
- (II) in the liquid phase composition calculated by the following solid-liquid equilibrium equation, the total quantity of said compounds (a) to (f) is 40% by weight or more and the viscosity of this liquid phase is 500 cSt or lower, ##EQU3## wherein X.sub.i is the equilibrium mole fraction of a component i in the liquid phase of said composition,
- .DELTA.H.sup.f.sub.i is the heat of fusion (cal.mol.sup.-1) of said component i as a pure substance,
- T.sup.f.sub.i is the melting point (K) of said component i as a pure substance,
- T is the temperature (K) of the system, and
- R is the gas constant (cal.mol.sup.-1.K.sup.-1)
- 2. The method of claim 1 wherein the temperature of step (iii) is -50.degree. C. and the portion of solid phase is at a temperature of -50.degree. C.
- 3. The method of claim 1 wherein the dielectric material is a plastic film.
- 4. The method of claim 3 wherein the plastic film is a polyolefin film.
- 5. The method of claim 4 wherein the polyolefin film is polypropylene film.
- 6. In the method of operating an oil filter capacitor of the type capable of operating at temperatures as low as "40.degree. C., said method including the steps of charging and discharging said capacitor at a temperature as low as -40.degree. C., the improvement which comprises:
- employing as said electrical insulating oil an oil composition comprising 45% by weight or more of at least 2 members selected from the group consisting of the following 6 components and the remainder of non-condensed bicyclic aromatic hydrocarbons having not more than 17 carbon atoms except said 6 components:
- (a) m-ethylbiphenyl,
- (b) p-ethylbiphenyl,
- (c) o-benzyltoluene,
- (d) m-benzyltoluene,
- (e) p-benzyltoluene, and
- (f) 1,1-diphenylethane
- and is characterized in that, when the temperature of said position is -40.degree. C.,
- (I) the total quantity of solid phase obtained by calculating according to the following solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of said composition, and
- (II) in the liquid phase composition calculated by the following solid-liquid equilibrium equation, the total quantity of said compounds (a) to (f) is 40% by weight or more and the viscosity of this liquid phase is 500 cSt or lower, E1 ? ##STR4## wherein X.sub.i is the equilibrium mole fraction of a component i in the liquid phase of said composition,
- .DELTA.H.sup.f.sub.i is the heat of fusion (cal.mol.sup.-1) of said component i as a pure substance, T.sup.f.sub.i is the melting point (K) of said component i as a pure substance,
- T is the temperature (K) of the system, and
- R is the gas constant (cal.mol.sup.-1.K.sup.-1)
- 7. The method of claim 6 wherein the operating temperature is as low as -50.degree. C. and the charging and discharging is at a temperature as low as -50.degree. C.
- 8. The method of claim 6 wherein the capacitor comprises a dielectric material of a plastic film.
- 9. The method of claim 8 wherein the plastic film is a polyolefin film.
- 10. The method of claim 9 wherein the polyolefin film is polypropylene film.
Priority Claims (1)
Number |
Date |
Country |
Kind |
61-208541 |
Sep 1986 |
JPX |
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CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 093,813, filed Sept. 4, 1987, now U.S. Pat. No. 5,017,733.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
4586972 |
Yokotani et al. |
May 1986 |
|
4750083 |
Sato et al. |
Jun 1988 |
|
5015793 |
Sato et al. |
May 1991 |
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5017733 |
Sato et al. |
May 1991 |
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Foreign Referenced Citations (1)
Number |
Date |
Country |
3127905 |
Feb 1983 |
DEX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
93813 |
Sep 1987 |
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