Analysis of treeing phenomena by simultaneous measurement of discharge magnitude and discharge luminescence of single pulse

This paper reports on the investigation of the treeing phenomena by measuring simultaneously discharge magnitude and discharge luminescence of single pulse. Treeing experiments were conducted using a PMMA block which had a needle shape void on the tip of needle electrode. One cycle of the ac applied voltage was divided into twenty equal phase angle areas, and they were named φ₁-φ₂₀ in order from the negative peak point of the applied voltage. The ac voltage was applied to the needle electrode, and the discharge pulses and discharge luminescences were measured at the same time at φ₃-φ₉ in positive polarity. As a result, the discharge luminescence at φ₃,φ₄ occurred mainly in the void area independently of the discharge magnitude. At φ₃-φ₉, the discharge luminescence was observed in the void area when the discharge magnitude was small, in the tree area when it was comparatively large. The discharge luminescence reached near the tip of tree channel. However at these phase angles, the discharge luminescence was observed only in the void area