The effect of water treeing on the electric field distribution of XLPE. Consequences for the dielectric strength

This paper describes the influence of water trees on dielectric properties of flat samples cut from a HV crosslinked polyethylene (XLPE) cable insulation. In order to obtain experimental results in a short period of time, we used accelerated aging conditions of voltage and frequency as well as different techniques for producing a multitude of artificial water tree inception points. The average value of the water tree permittivity and a law for the time-dependence of permittivity inside the treed degraded areas were deduced from measurements of capacitance and water tree lengths. On the basis of the experimental knowledge of permittivity and water tree length, we determined with analytical numerical methods, the distribution of the electric field for different shapes of treed regions. Because of the increase in length and permittivity of the water tree, the electric field in front of the degraded area is amplified, which is an important factor of risk leading to the electric breakdown.

[1]  M. Acedo,et al.  The cylindrical capacitive model for water treeing degradation in extruded HV cables , 1995, Proceedings of 1995 IEEE 5th International Conference on Conduction and Breakdown in Solid Dielectrics.

[2]  I. Radu,et al.  Electric field calculations in polymers in the presence of water trees , 1995, Proceedings of 1995 IEEE 5th International Conference on Conduction and Breakdown in Solid Dielectrics.

[3]  R.D. Naybour,et al.  Water treeing-a personal saga , 1990, IEEE Electrical Insulation Magazine.

[4]  J. Filippini,et al.  Some mechanical aspects of the propagation of water trees in polyethylene , 1982, Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1982.

[5]  J. D. Cross,et al.  Electrical behaviour and structure of water trees in relation to their propagation , 1983, Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1983.

[6]  R. J. Densley,et al.  Final Breakdown Mechanism Of Water Treeing , 1991, 1991 Annual Report. Conference on Electrical Insulation and Dielectric Phenomena,.

[7]  J. Filippini,et al.  The morphology and behavior of the water tree , 1993 .

[8]  H. Tanaka,et al.  A Study of Electrical Tree Initiation from Water Tree , 1991, 1991 Annual Report. Conference on Electrical Insulation and Dielectric Phenomena,.

[9]  P. Notingher,et al.  A study on the dependence of water tree permittivity with time , 1996, Proceedings of Conference on Electrical Insulation and Dielectric Phenomena - CEIDP '96.

[10]  J. Filippini,et al.  Water tree induced breakdown in polyethylene , 1992, [1992] Proceedings of the 4th International Conference on Conduction and Breakdown in Solid Dielectrics.

[11]  A. Bulinski,et al.  Water treeing in binary linear polyethylene blends: the mechanical aspect , 1994 .

[12]  Takao Miyashita,et al.  Deterioration of Water-Immersed Polyethylene-Coated Wire by Treeing , 1971, IEEE Transactions on Electrical Insulation.

[13]  F. Stucki,et al.  Dielectric properties of single water trees , 1992, [1992] Proceedings of the 4th International Conference on Conduction and Breakdown in Solid Dielectrics.