Ternary gas mixtures for high-voltage industrial insulation

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5898735

Pace, M O; Chan, C C; Christophorou, L G

New gas dielectrics for insulating power apparatus (e.g., gas insulated transmission lines (GITL) are evaluated. The comprehensive Oak Ridge National Laboratory gas dielectrics program has found that a mixture of gases, chosen via the fundamental physics of electron density and energy control and other chemical and physical properties, is best for insulation in a given application. Particular attention was given to mixtures using large proportions of an electron-moderating gas (viz., N/sub 2/, CHF/sub 3/, or 1,1,1-C/sub 2/H/sub 3/F/sub 3/) and smaller quantities of two electron attaching gases: SF/sub 6/ and one fluorocarbon (e.g., c-C/sub 4/F/sub 8/). The proportions were sought at which the three gases function best as a team, moderating free electrons from higher to lower energies and there attaching them. Small amounts of the electron attaching additives can drastically raise the dielectric strength of the moderator. Certain combinations of SF/sub 6/ and fluorocarbons do not produce the undesirable spark by-products associated with either SF/sub 6/ or fluorocarbons alone and also show improved negative polarity impulse breakdown characteristics over pure SF/sub 6/. Small scale breakdown measurements were made of various ternary mixtures in the GITL geometry: concentric cylinders, with intentionally roughened surfaces. It was found that nitrogen moderates electrons to extremely low energies, where SF/sub 6/ attaches; the dipolar gases moderate to somewhat higher energies, where some fluorocarbons attach best. Optimum ternary mixtures are identified (e.g., 20% SF/sub 6/ + 10% c-C/sub 4/F/sub 8/ + 70% N/sub 2/; 20% SF/sub 6/ + 15% c-C/sub 4/F/sub 8/ + 65% CHF/sub 3/). These will be discussed for possible use in power apparatus.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5898735
• Report Number(s): CONF-8110129-1; ON: DE82002779
• Country of Publication: United States
• Language: English

Related Subjects

200300* -- Electric Power Engineering-- Power Transmission & Distribution-- (-1989)
24 POWER TRANSMISSION AND DISTRIBUTION
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
BREAKDOWN
CABLES
CARBON COMPOUNDS
CARBON FLUORIDES
CONDUCTOR DEVICES
DATA
DIELECTRIC PROPERTIES
DISPERSIONS
ELECTRIC CABLES
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATION
ELECTRICAL PROPERTIES
ELEMENTS
EQUIPMENT
EXPERIMENTAL DATA
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GAS-INSULATED CABLES
GASES
HALIDES
HALOGEN COMPOUNDS
INFORMATION
MIXTURES
NITROGEN
NONMETALS
NUMERICAL DATA
PERFORMANCE TESTING
PHYSICAL PROPERTIES
POWER TRANSMISSION LINES
SULFUR COMPOUNDS
SULFUR FLUORIDES
TESTING