THE SIGNIFICANCE OF THE WEIBULL THRESHOLD IN SHORT-TERM BREAKDOWN STATISTICS

Routine breakdown tests performed on large populations of laboratory-a ged polyethylene insulated power cable slices and slices taken from ag ed cables are analyzed according to a Weibull model. The unaged refere nce populations are described by a three-parameter distribution, i.e. with a non-zero location parameter or threshold. On the contrary, the aged populations may be fitted by a simple two-parameter model. A tent ative interpretation stating a threshold dependence on aging is propos ed on the basis of previous results.