KIEE International Transactions on Electrophysics and Applications

The Korean Institute of Electrical Engineers (대한전기학회)
권호 표지

Effects of Temperature and Pressure on the Breakdown Characteristics of Liquid Nitrogen

  • Baek, Seung-Myeong (Dept. of Electrical Engineering, Gyeongsang National University and Engineering Research Institute) ;
  • Joung, Jong-Man (Dept. of Electrical Engineering, Gyeongsang National University and Engineering Research Institute) ;
  • Kim, Sang-Hyun (Dept. of Electrical Engineering, Gyeongsang National University and Engineering Research Institute)
  • Published : 2003.10.01
Download PDF
⟨ Previous Next ⟩

Abstract

For practical electrical insulation design of high temperature superconducting (HTS) power apparatuses, knowledge of the dielectric behavior of both liquid nitrogen (L$N_2$) and subcooled liquid nitrogen (SL$N_2$) are essential. To achieve SL$N_2$ at atmospheric pressure, cryostat was designed and constructed. By pumping up the L$N_2$ in the outer dewar, the temperature of L$N_2$ in the inner dewar at atmospheric pressure can be controlled. The breakdown characteristics of L$N_2$ in quasi-uniform and non-uniform electrical fields for temperatures ranging from 77 K to 65 K at atmospheric pressure and pressure ranging from 0.1 to 0.5 MPa were investigated experimentally. The experimental data suggested that the breakdown voltage (BDV) of L$N_2$ is both highly temperature and pressure dependent. We also carried out statistical analysis of the experimental results using the Weibull distribution. The Weibull shape parameter m for the sphere-to-plane electrodes in SL$N_2$ was estimated to be 11 to 18.

Keywords

References

  1. F. Y. Chu, 'Application of High Temperature Superconducting Materials in the Electric Power System and Ontario Hydro Perspective', World Congress on Superconductivity, Houston, pp. 129-138, 1998
  2. B. B. Gamble, G. L. Snitchler, and R. E. Schwall, 'Prospects for HTS Applications', IEEE Trans. On Magnets, vol. 32, No.4, pp. 2714-2719, 1996
  3. J. Gerhold, 'Properties of cryogenic insulants', Cryogenics, vol. 38, pp. 1062-1081, July 1998
  4. J. Gerhold, 'Cryogenic Liquids-A Prospective Insulation Basis for Future Power Equipment', IEEE Trans. on Dielectrics and Electrical Insulation, vol. 9, No.1, pp. 68-75, 2002
  5. N. Harakawa, H. Sakakibara, H. Goshima, M. Hikita and, H. Okubo, 'Breakdown mechanism of liquid nitrogen viewed from area and volume effects', IEEE Trans. on Dielectrics and Electrical Insulation, vol. 4, No. 1, pp. 127-134, 1997
  6. Sang-Hyun Kim, Jong-Man Jeong, Young-Seck Kim, Cheon-Oh Kim and, Seung-Myeong Baek, 'Influence of bubble size and flow velocity on AC electrical breakdown characteristics of $LN_2$,' Cryogenics, vol. 42, pp. 411-414, 2002
  7. J. Suehiro, T. Takahashi, M. Miwama, and M. Hara, 'Influence of Liquid Temperature and Electrode Size on Insulated Breakdown Characteristics in Saturated Superfluid Helium', Electrical Engineering in Japan, vol. 128, No.3, pp.16-23, 1999
  8. M. Butcher, A. Neuber, H. Krompholz, and L. L. Hatfield, 'Surface Flashover in Liquid Nitrogen', Conference on Electrical Insulation and Dielectric Phenomena, vol. 2, pp. 645-657, 1999