Analysis of discharge magnitude and discharge luminescence of phase angle area on tree initiation

This research is performed to analyze the treeing phenomena by discharge magnitude and discharge luminous quantity in each phase angle. The purpose of this study is to predict the tree initiation from the void. The discharge magnitude and the discharge luminous image are measured by the special measurement system to analyze discharge pulses and discharge luminescence at several phase angle areas of applied voltage. One cycle of an applied voltage was divided into twenty areas, labeled φ_1-20 in order from the negative peak point of applied ac voltage. The discharge magnitude and luminous quantity in φ₃ increase immediately before tree initiation. In this experimental condition, φ₃ is the phase angle area in which the discharge initiates. The discharge magnitude is proportional to the product of (dv/dt) and instantaneous value (Veb) of applied voltage, dv/dt is the differential value of applied voltage. However, the discharge magnitude at φ₃ increases just before tree initiation and then it is not the proportional relation. Therefore, that it is not the proportional relation is imminent in the tree initiation. It is considered to be useful information for prediction of tree initiation