TY - JOUR

T1 - Role of number of consecutive voltage zero-crossings in propagation of water trees in polyethylene

AU - Kaneko, Daisaku

AU - Maeda, Tomoya

AU - Ito, Toshihide

AU - Ohki, Yoshimichi

AU - Konishi, Takeshi

AU - Nakamichi, Yoshinobu

AU - Okashita, Minoru

N1 - Funding Information:
This work was partially supported by the Research on Creative Energy and Environments, a research project in the Advanced Research Institute for Science and Engineering, Waseda University, Japan.

PY - 2004/8

Y1 - 2004/8

N2 - Effects of superposition of a low-frequency (0.1 to 50 Hz) voltage and a high-frequency 2 kHz voltage on the growth of water trees in polyethylene are examined. It has become clear that both the number of total voltage zero-crossings during the whole voltage application period and the number of consecutive voltage zero-crossings in the instant of the polarity reversal of the low-frequency voltage play important roles in the length and shape of water trees. Namely, the water tree length becomes longer as the number of total zero-crossings increases. Furthermore, among the voltages with the same number of total zero-crossings, the length becomes even longer with a prolonged shape in the direction of electric field as the number of consecutive zero-crossings increases. Effects of superposition of a high-frequency voltage onto a dc voltage are also examined. In this case, the dc voltage seems not to have any influence to the tree growth. By assuming the presence of space charge around the water-tree tip, the effective zero-crossings become only sensitive to the high-frequency component. Therefore, this result also indicates that the number of voltage reversals at the tree tip plays a crucial role in the growth of water trees.

AB - Effects of superposition of a low-frequency (0.1 to 50 Hz) voltage and a high-frequency 2 kHz voltage on the growth of water trees in polyethylene are examined. It has become clear that both the number of total voltage zero-crossings during the whole voltage application period and the number of consecutive voltage zero-crossings in the instant of the polarity reversal of the low-frequency voltage play important roles in the length and shape of water trees. Namely, the water tree length becomes longer as the number of total zero-crossings increases. Furthermore, among the voltages with the same number of total zero-crossings, the length becomes even longer with a prolonged shape in the direction of electric field as the number of consecutive zero-crossings increases. Effects of superposition of a high-frequency voltage onto a dc voltage are also examined. In this case, the dc voltage seems not to have any influence to the tree growth. By assuming the presence of space charge around the water-tree tip, the effective zero-crossings become only sensitive to the high-frequency component. Therefore, this result also indicates that the number of voltage reversals at the tree tip plays a crucial role in the growth of water trees.

KW - Low density polyethylene

KW - Polymeric insulation

KW - Power cable

KW - Tree length

KW - Water tree

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U2 - 10.1109/TDEI.2004.1324360

DO - 10.1109/TDEI.2004.1324360

M3 - Article

AN - SCOPUS:6344243611

VL - 11

SP - 708

EP - 714

JO - IEEE Transactions on Dielectrics and Electrical Insulation

JF - IEEE Transactions on Dielectrics and Electrical Insulation

SN - 1070-9878

IS - 4

ER -