Influence of frequency on electrical tree initiation in high-density polyethylene

In this paper, the electrical tree initiation characteristics of high-density polyethylene (HDPE) under AC voltage with frequency ranging from 50 Hz to 100 kHz were studied. With the increase of frequency, the tree initiation voltage (TIV) firstly increases and then decreases after a peak value at 10 kHz is reached. However, the increase of frequency results in the decrease of the minimum of TIV and the increase of the dispersivity of TIV. There are 4 kinds of tree initiation shape (TIS): branch tree, bush tree, trunk tree and breakdown tree. With the increase of frequency, the kinds of TIS increase and the primary TIS changes from branch tree to bush tree. The influence of frequency on TIV and TIS were discussed.