Simultaneous measurement of microscopic image and discharge pulses at the moment of electrical tree initiation

摘要

The initiation and growth of an AC electrical tree has been considered to be an important factor of electrical breakdown in a solid insulator. The growth of an AC tree after its initiation is accompanied by partial discharges in the tree pipe, and eventually leads to the complete breakdown. There are some reports which dealt with the treeing phenomena and the transition of its discharge pulse pat terns[1]–[3]. However, most of them dealt with largely grown trees. On the other hand, it is very important for the fundamental understanding of treeing, to clarify the phenomena of initiation and growth of an "initial tree", whose length is below 10–20μm. However, as the phenomena of tree initiation and growth of initial tree take place within a few seconds, it has been very difficult to observe and record them.