Effect of Applied Voltage Frequency on Electrical Treeing in 22 kV Cross-linked Polyethylene Insulated Cable
This paper presents the experimental results on effect of applied voltage stress frequency to the occurrence of electrical treeing in 22 kV cross linked polyethylene (XLPE) insulated cable.Hallow disk of XLPE insulating material with thickness 5 mm taken from unused high voltage cable was used as the specimen in this study. Stainless steel needle was inserted gradually into the specimen to give a tip to earth plane electrode separation of 2.50.2 mm at elevated temperature 105-110°C. The specimen was then annealed for 5 minute to minimize any mechanical stress build up around the needle-plane region before it was cooled down to room temperature. Each specimen were subjected to the same applied voltage stress level at 8 kV AC rms, with various frequency, 50, 100, 500, 1000 and 2000 Hz. Initiation time, propagation speed and pattern of electrical treeing were examined in order to study the effect of applied voltage stress frequency. By the experimental results, initial time of visible treeing decreases with increasing in applied voltage frequency. Also, obviously, propagation speed of electrical treeing increases with increasing in applied voltage frequency.Furthermore, two types of electrical treeing, bush-like and branch-like treeing were observed.The experimental results confirmed the effect of voltage stress frequency as well.
 J. V. Champion, S. J. Dodd, Y. Zhao, A. S. Vaughan, M. Brown, A.E.
Davies, S. J. Sutton and S. G. Swingler, "Morphology and Growth of Electrical Trees in a Propylene/ethylene Copolymer", IEEE Transaction on Dielectric and Electrical Insulation, Vol. 8, pp. 284-292, 2001.
 J. V. Champion, S. J. Dodd, A. S. Vaughan, Y. Zhao, and S. J. Sutton,
"Effect of Voltage, Temperature and Morphology on Electrical Treeing
in Polyethylene Blends", Proceedings of Dielectric Materials,
Measurement and Applications, No.473, pp. 35-40, 2000.
 E. David, J. Parpal, and J. Crine, "Influence of Internal Mechanical Stress and Strain on Electrical Performance of Polyethylene", IEEE
Transaction on Dielectric and Electrical Insulation, Vol. 3, pp. 248-57,
 Y. Zhao, A. S. Vaughan, J. V. Champion, S. J. Dodd, and S. J. Sutton,
"The structure of Electrical Trees in Semi-crystalline Polymers",Proceedings of Dielectric Materials, Measurement and
Applications,London Guildhall University UK, IEE Conference Publication, No. 473, pp. 314-319, 2000.
 A. Xie, X. Zheng, S.Li and G.Chen. "Investigations of electrical trees in
the inner layer of XLPE cable insulation using computer
recording monitoring",IEEE Transaction on Dielectric and Electrical Insulation,Vol.17, pp.685-693, 2010.
 A. Rawangpia, B. Marungsri and N. Chomnawang "
accelerated ageing test of 22 kV XLPE cable for distribution system
applications in Thailand", World Academy of Science, Engineering and
Technology, Issue 65, pp.220-225, 2010.
 N. Hozumi, M.Okamoto and H.Fukagawa
morphology on electrical tree initiation in polyethylene under AC and
impulse voltages", IEEE Transaction on Dielectric and Electrical
Insulation,Vol.25, pp.707-714, 1990.
 X.Zheng and G.Chen, "Propagation mechanism of electrical tree in
XLPE cable insulation by investigating a double electrical tree
structure",IEEE Transaction on Dielectric and Electrical
Insulation,Vol.15, pp.800-807, 2008.
 A.S.Xie and X.Q.Li, "Electrical trees in inner and outer layer of
different voltage rating XLPE cable insulation",
Symposium on Electrical Insulating Materials
 N. Yoshimura, E. Hirade, Y. Changmin, H. Miyata and T. Niwa,
"Effect of Interface Pressure on Treeing Deterioration in
Polyethylene", Proceeding of International Conference on Property
and Application of Dielectric Material, pp. 444
 M.N. Arbab and D.W. Auckland: "Growth of electrical trees
insulation" IEE Proceeding of Science, Vol. 136, No
 F. Noto and N. Yoshimura, “Voltage and Frequency Dependence of
Tree Growth in Polyethylene”, IEEE Conference on Electrical
Insulationand Dielectric Phenomena (CEIDP), pp. 206-217, 1974.