Voltage Zero-crossing as a Factor Inducing Water Trees

Tomoya Maeda, Daisaku Kaneko, Yoshimichi Ohki, Takeshi Konishi, Yoshinobu Nakamichi, Minoru Okashita

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


We have been examining the effects of superposition of a high-frequency voltage to various voltages such as dc, low-frequency (0.1 to 5 Hz), and power-frequency voltages on the development of water trees in polyethylene. We have made clear that the number of voltage zero-crossings is a decisive factor in the length of water trees. In the present research, the water tree shapes grown under the various superposed voltages were carefully observed. As a result, the water tree tends to become a hand-like shape if the frequency of the lower-frequency component is between 0 and 0.5 Hz, while it becomes spherical if the frequency is higher than 1.0 Hz. This result is explained by assuming that the water tree shape is governed by the number of consecutive voltage zero-crossings. By combining the results reported in our former papers, it can be concluded that the voltage zero-crossing is a decisive factor for the formation of water trees. Frequent mechanical oscillation at the tree tip due to the Maxwell stress should play a significant role.

Original languageEnglish
Pages (from-to)51-56
Number of pages6
JournalThe transactions of the Institute of Electrical Engineers of Japan.A
Issue number1
Publication statusPublished - 2005


  • dielectric aging
  • polyethylene
  • power cable
  • water tree

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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