High voltage cables with extruded insulationߞStatistical controls and reliability evaluation

Fluctuations as a basis for the Weibull statistics of dielectric breakdown

“…Exchanges between the clusters can occur and if the material is weakly conducting these exchanges lead to electrical noise (6). It has been shown that the noise power generated in this manner is that of the commonly observed power law form in frequency P ( w ) ex w-2 ( 1 -m ) ( 1 ) where w is the frequency and m the correlation index for the inter -cluster exchanges. In the particular case of diffusive transport m takes the value of 0.5, giving the inverse frequency relationship so commonly observed in conductors (7).…”

“…Weibull plots are commonly used (1)(2)(3)(4) to present the cumulative probability of breakdown as a function of either electric field or of time. In general linear plots have been obtained which allow the ageing characteristics of the material under investigation to be predicted.…”

On the statistical testing of solid dielectrics

“…Generally, most authors agree on the validity of the two-dimensional Weibull distribution, which is in fairly good agreement with experimental results. Metra et al [4] Solid materials in practical insulation systems are stressed in conjunction with one or more other materials.…”