Gaseous dielectric compositions

A process for substantially eliminating carbon tracking formation and for improving dielectric strength in a dielectric fluid during an electrical discharge from an electrical conductor which comprises maintaining in contact with the electrical conductor during operation a gaseous dielectric composition consisting essentially of at least one mixture selected from the group consisting of SF.sub.6 --(C.sub.2 F.sub.5).sub.2 O over the range of about 1 to 55 mole percent of SF.sub.6, CO.sub.2 --(CF.sub.3).sub.2 O over the range of about 1 to 45 mole percent of CO.sub.2, and CO.sub.2 --(C.sub.2 F.sub.5).sub.2 O over the range of about 1 to 50 mole percent of CO.sub.2.

A composition for substantially eliminating carbon tracking formation, characterized in that the composition consists essentially of a mixture of at least one perfluorinated ether and a member selected from the group consisting of about 1 to 99 mole percent of SF.sub.6 and about 1 to 99 mole percent of SF.sub.6 plus about 1 to 75 mole percent of CO.sub.2, said perfluorinated ether having from 2 to 6 carbon atoms and a vapor pressure of at least about 100 Torr at 20.degree. C.

In combination:

• a. electrical apparatus having a chamber in which electric arcing occasionally occurs and in which dielectric strength is maintained;
• and
• b. a gaseous dielectric composition in said chamber for substantially eliminating carbon tracking formation and for electrical and insulating purposes, said gaseous dielectric composition consisting essentially of a mixture of at least one perfluorinated ether with from about 1 to 99 mole percent of SF.sub.6 and/or with from about 1 to 75 mole percent of CO.sub.2, said perfluorinated ether containing from 2 to 6 carbon atoms and having a vapor pressure of at least about 100 Torr at 20.degree. C.