Gaseous dielectric mixtures for suppressing carbon formation
AssigneeAllied Chemical Corporation
InventorsWhitney H. Mears, Sabatino R. Orfeo
Life of this patent
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Abstract
Carbon formation on voltage breakdown and sparking, and consequent carbon deposits on insulators and other surfaces, is suppressed in dielectric gases of halogenated alkanes by adding SF.sub.6 and/or CO.sub.2 to the halogenated alkane to form a gaseous dielectric mixture. Moreover, certain of the gaseous dielectric mixtures evidence unexpectedly high dielectric breakdown voltages. The gaseous dielectric mixtures are useful in high voltage coaxial lines, in transformers, in minisubstations, and the like.
Claims29
A process for suppressing carbon formation in a dielectric fluid during an electrical discharge from an electrical conductor which comprises contacting the electrical conductor during operation with a gaseous dielectric mixture consisting essentially of at least one halogenated alkane plus one member selected from the group consisting of CO.sub.2, in an amount of at least 15 mole percent, and a combination of SF.sub.6 and CO.sub.2 which, when plotted on a ternary diagram in mole percent of SF.sub.6 -CO.sub.2 -halogenated alkane, lies in regions rich in SF.sub.6 and CO.sub.2 defined by a line having at its extremities the points defined by
- 1 SF.sub.6 - 15 CO.sub.2 - 84 halogenated alkane
- 10 SF.sub.6 - 1 CO.sub.2 - 89 halogenated alkane,
- said halogenated alkane containing from 1 to 4 carbon atoms and at most one hydrogen atom, with the remaining hydrogen atoms replaced by at least one halogen selected from the group consisting of fluorine, chlorine and bromine, and having a vapor pressure of at least about 100 torr at 20.degree. C.
A process for suppressing carbon formation in a dielectric fluid during an electrical discharge from an electrical conductor which comprises contacting the electrical conductor during operation with a gaseous dielectric mixture consisting essentially of at least one halogenated alkane selected from the group consisting of CCl.sub.2 F.sub.2, CHClF.sub.2, CBrF.sub.3, CClF.sub.2 CClF.sub.2 and CClF.sub.2 CF.sub.3 plus one member selected from the group consisting of CO.sub.2, in an amount of at least 15 mole percent, and a combination of SF.sub.6 and CO.sub.2 which, when plotted on a ternary diagram in mole percent of SF.sub.6 - CO.sub.2 -halogenated alkane, lies in regions rich in SF.sub.6 and CO.sub.2 defined by a line having at its extremities the points defined by
- 1 SF.sub.6 - 15 CO.sub.2 - 84 halogenated alkane
- 10 SF.sub.6 - 1 CO.sub.2 - 89 halogenated alkane,
- said gaseous dielectric mixture evidencing improved dielectric strength.
A process for suppressing carbon formation in a dielectric fluid during an electrical discharge from an electrical conductor which comprises contacting the electrical conductor during operation with a gaseous dielectric mixture consisting of a mixture selected from the group consisting of
- a. 40 to 80 mole percent of SF.sub.6, balance CCl.sub.2 F.sub.2 ;
- b. 75 to 85 mole percent of SF.sub.6, balance CClF.sub.3 ;
- c. 60 to 85 mole percent of SF.sub.6, balance CBrF.sub.3 ;
- d. 40 to 50 mole percent of SF.sub.6, balance CHClF.sub.2 ;
- e. 25 to 90 mole percent of SF.sub.6, balance CClF.sub.2 CF.sub.3 ;
- f. a composition within an area on a ternary diagram defined by a polygon having at its corners the points defined by
- 45 SF.sub.6 - 5 CHF.sub.3 - 50 CHClF.sub.2
- 49 sf.sub.6 - 1 chf.sub.3 - 50 chcf.sub.2
- 98 sf.sub.6 - 1 chf.sub.3 - 1 chclF.sub.2
- 94 sf.sub.6 - 5 chf.sub.3 - 1 chclF.sub.2 ;
- g. a composition within an area on a ternary diagram defined by a polygon having at its corners the points defined by
- 30 SF.sub.6 - 55 CCl.sub.2 F.sub.2 - 15 CClF.sub.2 CF.sub.3
- 30 sf.sub.6 - 1 ccl.sub.2 F.sub.2 - 69 CClF.sub.2 CF.sub.3
- 98 sf.sub.6 - 1 ccl.sub.2 f.sub.2 - 1 cclF.sub.2 CF.sub.3
- 44 sf.sub.6 - 55 ccl.sub.2 F.sub.2 - 1 CClF.sub.2 CF.sub.3 ;
- and
- h. a composition within an area on a ternary diagram defined by a polygon having at its corners the points defined by
- 30SF.sub.6 - 15 CClF.sub.3 - 55 CClF.sub.2 CF.sub.3
- 30 sf.sub.6 - 1 cclF.sub.3 - 69 CClF.sub.2 CF.sub.3
- 98 sf.sub.6 - 1 cclF.sub.3 - 1 CClF.sub.2 CF.sub.3
- 84 sf.sub.6 - 15 cclF.sub.3 - 1 CClF.sub.2 CF.sub.3.
A carbon formation suppressant composition consisting essentially of at least one halogenated alkane plus both SF.sub.6 and CO.sub.2, said halogenated alkane containing from 1 to 4 carbon atoms and at most one hydrogen atom, with the remaining hydrogen atoms replaced by at least one halogen selected from the group consisting of fluorine, chlorine and bromine, and having a vapor pressure of at least about 100 Torr at 20.degree. C, said composition, when plotted on a ternary diagram, lying in the regions rich in SF.sub.6 and CO.sub.2 defined by a line having at its extremities the points defined by
- 1 SF.sub.6 - 15 CO.sub.2 - 84 halogenated alkane
- 10 SF.sub.6 - 1 CO.sub.2 - 89 halogenated alkane.
Dependencies are inferred from the claim text.