Fundamental Study on Charging Potential of Floating Electrode Modeled on Vacuum Interrupter under AC Voltage Application

This paper is described on the charging characteristics of floating electrode modeled on Vacuum Interrupter (VI). The experimental sample has a floating electrode between two ceramics cylinders. We prepared two kinds of samples which are equipped with or without shield rings inside of the floating electrode to relax an electric field around the triple junction of floating electrode. A charging signal was measured by a surface potential meter as a charging potential.As a result, in case of low voltage application, only an induced voltage in the floating electrode was measured depending on the capacitive dividing voltage of the sample and grounded objects around the sample. In case of high voltage application, not only induced voltage but also a positively charging potential was observed in the floating electrode regardless of sample configuration or polarity of applied voltage. This is due to the field electron emission from the floating electrode itself. The positive charging potential was increased almost linearly to the applied voltage. Comparing the samples, it was found that the sample without shield rings began to form a positive charge at a lower voltage application rather than the sample with shield rings.