Progress in Superconductivity and Cryogenics (한국초전도ㆍ저온공학회논문지)

The Korean Society of Superconductivity and Cryogenics (한국초전도저온학회)
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Study on the Dielectric Characteristics of Gaseous Nitrogen for Designing a High Voltage Superconducting Fault Current Limiter

  • Heo, Jeong-Il (Dept. of Electrical Engineering, Korea National University of Transportation) ;
  • Hong, Jong-Gi (Dept. of Electrical Engineering, Korea National University of Transportation) ;
  • Nam, Seok-Ho (Dept. of Electrical Engineering, Korea National University of Transportation) ;
  • Kang, Hyoung-Ku (Dept. of Electrical Engineering, Korea National University of Transportation)
  • Received : 2012.04.13
  • Accepted : 2012.05.08
  • Published : 2012.05.31
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Abstract

The study on the dielectric characteristics of gaseous insulation medium is important for designing current leads of superconducting machines using a sub-cooled liquid nitrogen ($LN_2$) cooling method. In a sub-cooled $LN_2$ cooling system, the temperature of gaseous insulation medium surrounding current leads varies from the temperature of coolant to 300 K according to the displacement between the electrode system and the surface of sub-cooled $LN_2$. In this paper, AC withstand voltage experiments on gaseous nitrogen according to temperature are conducted. Also, AC withstand voltage experiments on gaseous nitrogen according to pressure, size of electrode, and gap length between two electrodes are performed. It is found that there is a functional relation between the electrical breakdown voltage and the field utilization factor (${\xi}$). As a result, the empirical formula for estimating an electrical breakdown voltage is deduced by adopting the concept of field utilization factors. It is expected that the experimental results presented in this paper are helpful to design current leads for a high voltage superconducting apparatus such as a superconducting fault current limiter (SFCL) using a sub-cooled $LN_2$ cooling system.

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References

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Cited by

  1. Study on the Dielectric Characteristics of Gaseous, Liquid, and Solid Insulation Materials for a High Voltage Superconducting Apparatus vol.23, pp.3, 2013, https://doi.org/10.1109/TASC.2012.2236875
  2. A Study of the Dielectric Characteristics of Gaseous Nitrogen With Respect to the Electrode Material for Developing a High Voltage Superconducting Fault Current Limiter vol.25, pp.3, 2015, https://doi.org/10.1109/TASC.2014.2373654