Journal of the Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회논문지)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Shape and Dielectric Strength of Thermal Bubbles in Liquid Nitrogen

액체질소 중 열기포 형상 및 절연 특성

  • Baek, Seung-Myeong (Department of Fire Safety Engineering, Changwon Moonsung University) ;
  • Kim, Hae-Jong (Korea Electrotechnology Research Institute, HVDC Research Division)
  • 백승명 (창원문성대학 소방안전공학과) ;
  • 김해종 (한국전기연구원 HVDC 연구본부)
  • Received : 2015.04.20
  • Accepted : 2015.04.24
  • Published : 2015.05.01
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Abstract

In this paper, we study the insulating properties of the liquid nitrogen(LN2) including the thermal bubbles. The shape of the thermal bubbles in accordance with the current change was observed in the 77 K and 65 K LN2. According to the temperature of liquid nitrogen, bubbles were generated differently. The round shape of the bubble is occurred in 77 K LN2. But the layer shape of bubble is occurred in 65 K LN2. When the bubbles present, the dielectric strength of liquid nitrogen is low. However, the breakdown patterns were different according to the electrode arrangement. AC breakdown voltage(BDV) was lower than the DC BDV due to the influence of bubbles. Therefore, the design of a high-voltage superconducting equipments should consider the bubbles.

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References

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