Effect of Space Charge Accumulation in Insulating Material Formed by DC Voltage Application Through Air Gap on Discharge Inception Voltage

Abstract

In this paper, an accumulation of space charge in insulating materials and its effect on the discharge inception voltage were investigated by measuring the space charge distribution formed in the materials by applying a dc voltage to it through an air gap. In previous studies, the space charge accumulations in insulating materials were observed by applying the dc voltage to them through contacted electrodes. However, the voltage is applied to the material through the air gap in the actual usage of some insulating materials for motor windings. Therefore, we conducted the measurement of the space charge distribution in a sample with an air gap. The results showed that as space charge accumulates inside the insulating material, the voltage applied to the air gap increases, and the discharge inception voltage decreases.