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Dielectric Gases 371

FIGURE 14 Schematic of a compressed-gas insulated (CGI) cable. (Courtesy of Westinghouse Electric Corporation.)

By far the largest use of gas-insulated cables has been in optimize this benefit, a well-balanced growth in basic and
installations that are 100–200 m in length. The longest ca- applied research and industrial development in this area is
ble is 700 m (420 kV/1386 MVA). Research and develop- necessary.
ment have been conducted to develop gas-insulated cables
using SF 6 for 1200-kV transmission. Three-conductor ca-
bles (three-in-one), where the three-phase conductors are SEE ALSO THE FOLLOWING ARTICLES
arranged in a single enclosure, are also used up to 362 kV
transmission voltage. Gas-insulated technology is being
ATOMIC AND MOLECULAR COLLISIONS • MOLECULAR
further developed by considering flexible enclosure de-
ELECTRONICS • NANOELECTRONICS • POWER TRANSMIS-
signs for easier installation.
SION,HIGH VOLTAGE
Compressed-gas insulated cables have about two to
three times the load-carrying capability of comparable oil-
filled cables. Typically, a gas-insulated transmission cable
at a 242 kV system voltage can carry 3000 A, equivalent BIBLIOGRAPHY
to 1250 MVA, while at 1200 kV, 10,000 A, equivalent to
16 GVA, has been demonstrated. Christophorou, L. G. (ed.). (1980). “Gaseous Dielectrics II,” Pergamon
Press, Oxford.
Christophorou, L. G. (ed.). (1982). “Gaseous Dielectrics III,” Pergamon
V. CONCLUDING REMARKS Press, Oxford.
Christophorou, L. G. (ed.). (1984). “Electron–Molecule Interactions and
Their Applications,” Vols. 1 and 2, Academic Press, New York.
Recent advances in basic research, especially in electron- Christophorou, L. G., and Pace, M. O. (eds.). (1984). “Gaseous Di-
and ion-collision physics, have resulted in improved un- electrics IV,” Pergamon Press, Oxford.
derstanding of the dielectric properties of gases. This un- Christophorou, L. G., and Sauers, I. (eds.). (1991). “Gaseous Dielectrics
derstanding, in turn, has aided efforts to identify, improve, VI,” Plenum Press, New York.
Christophorou, L. G., Sauers, I., James, D. R., Rodrigo, H., Pace, M. O.,
and tailor new dielectric gases for a variety of electrical
Carter, J. G., and Hunter, S. R. (1984). IEEE Trans. Elect. Insul. EI-19,
insulation needs. 550–566.
Basic research is still needed to provide better under- Kunhardt,E.E.,andLuessen,L.H.(eds.).(1983).“ElectricalBreakdown
standing and a sounder scientific basis for the expected and Discharges in Gases,” Plenum Press, New York.
expansion in the uses of dielectric gases as insulants in Meek, J. M., and Craggs, J. D. (eds.). (1978). “Electrical Breakdown of
Gases,” Wiley, New York.
high-voltage transmission and distribution and other high-
Nasser, E. (1971). “Fundamentals of Gaseous Ionization and Plasma
voltage electrical equipment. The full potential of and ben- Electronics,” Wiley, New York.
efit from the use of gas dielectrics is yet to be realized. To Special Issue. (1990). IEEE Trans. Elect. Insul. 25 (1, February).