Mcgraw-Edison Company

Fred S Sadler

John Lapp

Vu H Viet

Paul F Hettwer

Clarance R Acker

Clarence R Acker

An insulating system is described that incorporates a cellulosic material which is impregnated with a nitrogen content no less than 0.2% by weight and a overall density not greater than 0.9 gm/cm.sup.3. This cellulosic material when impregnated by a dielectric liquid such as transformer oil, exhibits a more uniform electrical stress distribution than papers having a density greater than 0.9 gm/cm.sup.3. The insulating system thereformed is particularly useful for application in low stress areas such as the layer insulation in a distribution class transformer.

Electrical insulating system

The invention relates to a method for improving the thermal stability and dielectric integrity of a cellulosic web product. The cellulosic web is impregnated with a nitrogen donor compound such that the web contains not less than 0.2% by weight of the compound and thereafter impregnated with an aqueous vegetable protein solution at a pH of not less than about 8.5.

Process for making electrical insulating paper and the product thereof

An improved dielectric system for an electrical apparatus. The dielectric system includes a polymeric film impregnated with low molecular weight polybutene having an average number molecular weight in the range of 300 to 500. The dielectric system has improved dielectrical properties and the polybutene is biodegradable which minimizes the pollution of the atmosphere if the dielectric liquid is exposed to the atmosphere. Further extended service life can be achieved by the addition of a cyclohexyl amine to the liquid dielectric.

Dielectric system for an electrical apparatus

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.

Electrical capacitor having an impregnated dielectric

An electrical apparatus, such as a capacitor, having an improved dielectric system. The capacitor includes alternate layers of metal foil and a dielectric material comprising polymeric film, or a combination of polymeric film and paper, 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. The capacitor has improved corona characteristics and low dielectric losses, and the liquid dielectric composition is substantially biodegradable.

Electrical capacitor having an impregnated dielectric system

An electrical apparatus, such as a capacitor, having an improved dielectric system. The dielectric system includes a polymeric film impregnated with low molecular weight polybutene having an average number molecular weight in the range of 300 to 500. The dielectric system has improved dielectrical properties and the polybutene is biodegradable which minimizes the pollution of the atmosphere if the dielectric liquid is exposed to the atmosphere. Further extended service life can be achieved by the addition of a cyclohexyl amine to the liquid dielectric.

Capacitor with liquid polybutene dielectric

Cellulose material having improved resistance to thermal deterioration and having particular application as insulation material for electrical apparatus. The cellulose material is treated with an aqueous dispersion of a liquid, uncured, crosslinkable thermosetting resin, such as an epoxy resin, and a water soluble, nitrogen-containing compound. During curing of the resin, the cellulose molecules are believed to enter into the crosslinking reaction to provide a treated cellulosic product capable of withstanding the deteriorating action of heat over extended periods of time. A protein material, such as casein or isolated soy protein, can be added to the treating liquid and the protein not only contributes additional nitrogen groups to the treating media to further increase the thermal stability of the cellulose, but also acts as a film former. The thermal stability of the cellulose material can be further improved by the addition of an organic amine, such as melamine, to the treating liquid.

Growing community of inventors

Racine, WI, United States of America

Fred S Sadler