High voltage research (breakdown strengths of gaseous and liquid insulators) and environmental effects of dielectric gases. Semiannual report, April 1-September 30, 1981

Technical Report · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5278719

Christophorou, L G; James, D R; Pai, R Y

Electron attachment studies were performed on three perfluoroalkanes, two thioethers, n-C/sub 3/F/sub 8/, (CF/sub 3/)/sub 2/S, 1-C/sub 3/F/sub 6/, and 3,3,3-C/sub 3/F/sub 3/H/sub 3/. The attachment rates for CC1/sub 3/F were measured. The energies in dissociative electron attachment of C/sub 3/F/sub 8/, n-C/sub 4/F/sub 10/, and n-C/sub 6/F/sub 14/ were evaluated. For gases used in diffuse discharge interrupting switches, desirable characteristics and some candidate gas mixtures are discussed: The pressure effect on breakdown voltage was investigated in SF/sub 6/, N/sub 2/, and 1-C/sub 3/F/sub 6/; for the latter, (E/N)/sub lim/ increased approximately 25% from 26 kPa to 200 kPa. The breakdown voltages have been measured for SF/sub 6//1-C/sub 3/F/sub 6//moderating gas (CHF/sub 3/ or N/sub 2/) mixtures under both polarities of lightning impulse (1.2 ..mu..s rise, 50 ..mu..s fall) voltages. The effect of electrode by sparking on observed breakdown voltages were studied. The observed variations of time-to-breakdown for various mixutres are discussed. Methods for reducing the harmful effects of small conducting particles in gas-insulated apparatus were studied. The possible use of gases to form an insulating coating on offending particles, the effect of coating particles and ways to perform the coating were investigated. The immediate breakdown products of ternary mixtures containing SF/sub 6/, c-C/sub 4/F/sub 8/, and either N/sub 2/ or CHF/sub 3/ were observed. Long-term electrical and thermal stress of SF/sub 6/, c-C/sub 4/F/sub 8/ and N/sub 2/ mixtures produced no observable decomposition products. For sparking in SF/sub 6/, SF/sub 4/ was found to be a major product. The toxicity of gas mixtures before and after sparking was assessed. Nitrogen and unsparked SF/sub 6/ were found non-toxic, while sparked SF/sub 6/ and unsparked 2-C/sub 4/F/sub 6/ were found to be toxic. Studies of the effects of capacitance on the observed breakdown strengths of dielectric liquids showed that. Increased capacitance lowered the breakdown voltage, but less for external capacitance than for internal capacitance.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5278719
• Report Number(s): ORNL/TM-8158; ON: DE82011299
• Country of Publication: United States
• Language: English

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AC SYSTEMS
BREAKDOWN
CARBON COMPOUNDS
CARBON FLUORIDES
DATA
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELECTRON ATTACHMENT
ELEMENTS
ENERGY SYSTEMS
ENVIRONMENTAL EFFECTS
EXPERIMENTAL DATA
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HVAC SYSTEMS
INFORMATION
IONIZATION
MATERIALS
NITROGEN
NONMETALS
NUMERICAL DATA
PHYSICAL PROPERTIES
POWER SYSTEMS
PRESSURE DEPENDENCE
SULFUR COMPOUNDS
SULFUR FLUORIDES
TOXICITY