The electrical breakdown characteristics of liquid nitrogen (LN 2) should be investigated for developing of a high voltage superconducting machine. This paper deals with the experimental study for the verification of dielectric characteristics of sub-cooled LN2 in accordance with utilization factors. AC dielectric experiments were carried out by using sphere-plane electrode systems. The utilization factors of simulated electrode systems were controlled by gap distance between two electrodes and diameter of a sphere electrode. Also, dielectric experiments according to various pressures, 1.25, 1.5 and 2 bar, by gaseous nitrogen were carried out. In this paper, the electrical breakdown criteria of sub-cooled LN2 conditions are derived with various sphere diameters. In addition, the sub-cooled LN2 condition and saturated LN2 condition were compared with AC dielectric characteristics. Research results could be applicable to designing of high voltage superconducting applications such as superconducting fault limiters (SFCLs), cables and large-capacity transformers.
Bibliographical noteFunding Information:
Manuscript received October 20, 2009. First published March 25, 2010; current version published May 28, 2010. This research was supported by the National Research Laboratory Program through the Korea Science and Engineering Foundation funded by the Ministry of Education, Science and Technology (R0A-2007-000-20063-0).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering