Frequency dependence of breakdown performance of XLPE with different artificial defects

In this paper, the effect of the applied field frequency on the breakdown performances of cross-linked polyethylene (XLPE) insulation was investigated. Three kinds of artificial defects, namely an inserted needle, a needle void and a knife void, were introduced into a 10 kV commercial XLPE cable, to simulate real defects that may be introduced during on-site service. Breakdown tests were conducted in transformer oil at room temperature using a frequency-tuned resonant test system in a frequency range from 20 to 300 Hz. It was found that the breakdown voltage of specimens with the inserted needle was sensitive to the applied field frequency, and the breakdown voltage showed a maximum value at about 240 Hz. However, for other two kinds of specimens with the needle void and knife void, the breakdown behavior shows a weak relation with the applied field frequency. The breakdown voltages of the specimens with the needle and void are 25 kV and 20 kV respectively. It was further found that side channels appeared on the flank of the main channel of the breakdown path in the specimen with the inserted needle, and the frequency dependence of fractal dimension D of the side channel in the breakdown path are similar to that of electrical trees before breakdown, which may consequently lead to the maximum value in the experimental results.

[1]  J. Devins.  The physics of partial discharges in solid dielectrics , 1984, Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1984.

[2]  Noriyuki Shimizu,et al.  Initiation mechanism of electrical tree under alternating stress-electron impact or UV photo-degradation? , 2001, ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117).

[3]  R. Ross,et al.  Graphical methods for plotting and evaluating Weibull distributed data , 1994, Proceedings of 1994 4th International Conference on Properties and Applications of Dielectric Materials (ICPADM).

[5]  J. Devins,et al.  The 1984 J. B. Whitehead Memorial Lecture the Physics of Partial Discharges in Solid Dielectrics , 1984, IEEE Transactions on Electrical Insulation.

[6]  N. Shimizu,et al.  Electrical tree initiation , 1998 .

[7]  Yu Li,et al.  Partial Discharge Pattern Characteristic of HV Cable Joints with Typical Artificial Defect , 2010, 2010 Asia-Pacific Power and Energy Engineering Conference.

[8]  Katsutoshi Kudo,et al.  Fractal analysis of electrical trees , 1998 .

[9]  Weibull statistics in short-term dielectric breakdown of thin polyethylene films [comments and reply] , 1995 .

[10]  S. Katakai.  Design of XLPE cables and soundness confirmation methods to extra high voltage XLPE cables , 2002, IEEE/PES Transmission and Distribution Conference and Exhibition.

[11]  H. Ahmad,et al.  Partial discharge characteristics of XLPE cable joint and interfacial phenomena with artificial defects , 2008, 2008 IEEE 2nd International Power and Energy Conference.

[12]  E. Gockenbach,et al.  The selection of the frequency range for high-voltage on-site testing of extruded insulation cable systems , 2000 .

[13]  Hitoshi Inoue,et al.  Study on detection for the defects of XLPE cable lines , 1996 .

[14]  R. Ross,et al.  Bias and standard deviation due to Weibull parameter estimation for small data sets , 1996 .

[15]  L. Pietronero,et al.  Fractal Dimension of Dielectric Breakdown , 1984 .

[16]  G. Stevens,et al.  Stochastic modelling of electrical treeing: fractal and statistical characteristics , 1990 .

[17]  R. Densley,et al.  An Investigation into the Growth of Electrical Trees in XLPE Cable Insulation , 1979, IEEE Transactions on Electrical Insulation.

[18]  Masayuki Hikita,et al.  Partial discharge characteristics till breakdown for XLPE cable joint with an artificial defect , 2003, Proceedings of the 7th International Conference on Properties and Applications of Dielectric Materials (Cat. No.03CH37417).

[19]  C. Laurent,et al.  Weibull statistics in short-term dielectric breakdown of thin polyethylene films , 1993 .

[20]  A. Bulinski,et al.  The frequency effect of HV and electroluminescence in XLPE , 2002, Annual Report Conference on Electrical Insulation and Dielectric Phenomena.

[21]  Y. Ohki,et al.  The World's first long-distance 500 kV-XLPE cable line. 3. Underground apparatus , 2002 .

[22]  Allan Greenwood,et al.  Effects of Charge Injection and Extraction on Tree Initiation in Polyethylene , 1978, IEEE Transactions on Power Apparatus and Systems.

[23]  Shengtao Li,et al.  Investigations of electrical trees in the inner layer of XLPE cable insulation using computer-aided image recording monitoring , 2010, IEEE Transactions on Dielectrics and Electrical Insulation.

[24]  V. Englund,et al.  Synthesis and efficiency of voltage stabilizers for XLPE cable insulation , 2009, IEEE Transactions on Dielectrics and Electrical Insulation.

[25]  John C. Fothergill,et al.  Electrical degradation and breakdown in polymers , 1992 .

[26]  R. Eaton,et al.  Physical Model of Electric Aging and Breakdown of Extruded Pplymeric Insulated Power Cables , 1982, IEEE Transactions on Power Apparatus and Systems.

[27]  L. Dissado,et al.  Weibull Statistics in Dielectric Breakdown; Theoretical Basis, Applications and Implications , 1984, IEEE Transactions on Electrical Insulation.

[28]  Sweeney,et al.  Physical model for breakdown structures in solid dielectrics. , 1993, Physical review. B, Condensed matter.

[29]  R. Ross,et al.  Formulas to describe the bias and standard deviation of the ML-estimated Weibull shape parameter , 1994 .

[30]  W. Weibull.  A Statistical Distribution Function of Wide Applicability , 1951 .