In this paper, previous theoretical developments by one of the authors -relevant to the "enlargement law" - are applied for a benchmark between two alternative compounds candidate for the realization of the solid-extruded insulation of power cables. By resorting to the results of dielectric strength tests relevant to cable models, breakdown performances of full-size cables are investigated as a function of cable length. In particular, the focus is on the existence of the so-called crossing length, such that one of the two compounds performs better for cables longer than crossing length, and conversely the other for cables shorter than this. As a practical case-study, the breakdown performances of two cross-Linked Polyethylene (XLPE) compounds are compared on the basis of lightning impulse strength tests relevant to cable models, by analyzing various power cable voltage ratings, i.e. 6 kV, 20 kV, 150 kV and 400 kV. The application shows that, though the crossing length in fact exists, it is a strong function of cable size and voltage rating. As a general consequence, the choice of the best compound should be based on a comparison between the value of crossing length and typical installation lengths of real cables
[1]
Wolfgang Hauschild,et al.
Statistical techniques for high-voltage engineering
,
1992
.
[2]
John C. Fothergill,et al.
Electrical degradation and breakdown in polymers
,
1992
.
[3]
G. C. Montanari,et al.
A robust technique for the estimation of the two-parameter Weibull function for complete data sets
,
2002
.
[4]
M. Marzinotto.
On the application of the “enlargement law” to cable lines
,
2005,
2005 IEEE Russia Power Tech.
[5]
E. Occhini,et al.
A Statistical Approach to the Discussion of the Dielectric Strength in Electric Cables
,
1971
.
[6]
M. Pompili,et al.
Impulsive strength of power cables with different XLPE compounds
,
2006,
2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena.