Characteristics of electrical tree defect during the growth period in high‐voltage DC cable under stepped DC voltage.

In this study, the electrical tree mechanisms during a growth period from tens of microns to hundreds of microns were investigated for cross‐linked polyethylene under a stepped DC voltage. The results show that the electrical tree grows along the direction of the needle tip pointing to the ground, and the tree growth follows a typical single branch type. The growth of the electrical tree is mainly detected during the voltage rising process and is rarely observed during the voltage maintenance step. Moreover, the length increment of the tree decreases with the increase in the length of the initial tree. The simulation results for the charge transport in the needle–plane electrode suggest that these growth characteristics are associated with the energy released near the needle tip during the charge trapping and detrapping processes. [ABSTRACT FROM AUTHOR]