Optical observation of arcs in liquid nitrogen

Abstract

Liquid Nitrogen (LN2) has good insulation and arc-quenching properties. It can minimize the switchgear losses to a low level due to its cryogenic nature. Optical observation of LN2-arcs is very important for the future design of the Liquid Nitrogen Insulated metal enclosed Switchgear (LNIS). It would help in determining the spacers sizing, and the clearance distances between the LN2 Switch and the other equipment inside the LNIS system. Until now, no one has ever done the optical analysis of high-luminance arcs in the LN2 environment. The objective of this work was to determine the shape, size and current-density effects of arc plasmas in LN2. One type of electrode geometry and three types of electrode materials were used to study the LN2-arc characteristics. The influence of cryogenic environment on the arcs were thoroughly studied. Results showed that the arcs in LN2 have a direct relationship with the applied voltages, interrupting currents and the magnetic fields. The higher the interrupting current, the larger is the size of the arc. It was also observed that different electrodes materials have different shapes of arc plasmas. Magnetic fields can significantly influence the LN2-arc by increasing its size, patterning its shape and reducing its arcing time.