Skip to Main Content
Measurements were made to assess the AC breakdown voltages in liquid nitrogen (LN2) with different electrode configurations such as sphere-sphere, needle-needle, hemisphere-hemisphere, plane-plane, sphere-needle, etc. Experimental results reveal that the breakdown voltage is a function of electrode geometry and gap length. This study also addresses the effect on the breakdown strength of solid insulating materials under LN2 environment with a sphere-sphere electrode configuration. In this paper, special emphasis has been attributed to the effect on loss index of a variety of dielectrics dipped in LN2. The measured values of breakdown strength and loss index have been compared with those obtained under atmospheric condition. The study reveals that the breakdown strength of cellulosic materials like paper or pressboard increases manifold while the loss index decreases significantly when dipped in LN2 with variations of the order of 50% to 90%. However, for impervious noncellulosic materials like Perspex (acrylic glass) or presspahn, the increase in breakdown strength is not that pronounced and the decrease in loss index is of the order of 2 to 30%.
Dielectrics and Electrical Insulation, IEEE Transactions on (Volume:9 , Issue: 6 )
Date of Publication: Dec 2002