Abstract: An ester dielectric fluid for an AC capacitor with improved corona properties contains a minor amount of tert-butylanthraquinone. The ester may be 2-ethylhexylphthalate or diisononylphthalate, and an epoxide stabilizer is present.

Abstract: Dielectric compositions comprising benzyl esters of .alpha.-branched chain alkyl-substituted saturated monocarboxylic acids having improved thermal and chemical stability for extended periods of operation under varying conditions are provided.

Abstract: Electrical devices such as transformers and capacitors containing divinyltetramethyldisiloxane or methylvinylcyclosiloxanes as dielectric fluids are disclosed.

Abstract: Electrical devices such as transformers and capacitors containing certain silacyclopentenes as dielectric fluids are disclosed.

Abstract: An electrical capacitor having an improved dielectric system. The capacitor includes alternate layers of metal foil and polymeric dielectric film which is impregnated with a liquid dielectric composition composed of a mixture of mono-halogenated diphenyl oxide and a mono-halogenated alkyl diphenyl oxide where the alkyl group contains from 1 to 20 carbon atoms in the molecule. In processing the capacitor, the capacitor casing is vacuum dried at room temperature and the dielectric liquid is separately agitated under vacuum to remove gas from the liquid. The degassified liquid is introduced into the casing and the liquid is subjected to a vacuum while maintaining the capacitor at room temperature to impregnate the polymeric layers with the liquid. The capacitor has improved corona characteristics and low dielectric losses, and the liquid dielectric composition is substantially biodegradable.

Abstract: An oil-impregnated capacitor comprising a thin insulator sheet solely consisting of a plastic film and impregnated with an insulating oil, the aptitude of which is defined by both the oil absorption and the expansion coefficient of the film.

Abstract: A capacitor is disclosed of layers of metal foil alternating with insulating sheets impregnated with a dielectric fluid. The dielectric fluid comprises a mixture of 80 to 99% by weight mono-ethylated, mono-propylated, or mono-butylated biphenyl, biphenyl oxide, or biphenyl methane and about 1 to about 20% by weight di-ethylated, di-propylated, or di-butylated biphenyl, biphenyl oxide, or biphenyl methane.