High voltage research (breakdown strengths of gaseous and liquid insulators). Fourth quarterly report, period ending March 31, 1977

Technical Report · Wed Jun 01 00:00:00 EDT 1977

DOI:https://doi.org/10.2172/7102319· OSTI ID:7102319

Christophorou, L. G.; James, D. R.; Pai, R. Y.; Pace, M. O.; Mathis, R. A.; Bouldin, D. W.

The dc breakdown strengths of C/sub 7/F/sub 14/ (perfluoromethylcyclohexane), C/sub 7/F/sub 14/ (perfluoroheptene-1), and C/sub 4/F/sub 6/ (hexafluorobutadiene) have been found to be superior to SF/sub 6/ by a factor of 2.1, 1.2, and 1.4, respectively. Electron attachment rates and cross sections have been measured for C/sub 6/F/sub 10/ (perfluorocyclohexene) and C/sub 6/F/sub 12/ (perfluorodimethylcyclobutane) and were found to be very large to energies of approx. 1 eV. They correlate nicely with the superior breakdown strengths of these systems which are more than twice that of SF/sub 6/. The dc breakdown voltage, V/sub s/, for c-C/sub 4/F/sub 8/, iso-C/sub 4/F/sub 8/, and SF/sub 6/ was extended to higher voltages (to 300 kV). For the former two compounds, V/sub s/ obeys Paschen's law, but it deviates from it for SF/sub 6/. Mixtures of our best dielectric fluorocarbon gases such as C/sub 4/F/sub 6/ and c-C/sub 4/F/sub 8/ with N/sub 2/ do not show a ''saturation'' effect as does SF/sub 6/ and exhibit a synergistic behavior. Very importantly, the direct effect of the inelastic scattering properties of the gas via low-lying (approx. 1 to 4 eV) negative ion resonances on its breakdown strength has been demonstrated. Construction of a new high pressure, high voltage, variable temperature test chamber continued. Fabrication of cylindrical electrodes of variable degree of surface roughness, material composition and radius for applied testing has been completed. The results of the first phase of our diverter studies are reported.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7102319
• Report Number(s): ORNL/TM-5917
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
ELECTRICAL INSULATION
BREAKDOWN
RESEARCH PROGRAMS
CARBON FLUORIDES
DIRECT CURRENT
FABRICATION
GASES
NITROGEN
SULFUR FLUORIDES
TEST FACILITIES
CARBON COMPOUNDS
CRYOGENIC FLUIDS
CURRENTS
ELECTRIC CURRENTS
ELEMENTS
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
NONMETALS
SULFUR COMPOUNDS
200302* - Power Transmission & Distribution- DC Systems- (1989-)