The significance of the Weibull threshold in short-term breakdown statistics

Routine breakdown tests performed on large populations of laboratory-aged polyethylene insulated power cable slices and slices taken from aged cables are analysed according to a Weibull model. The unaged reference populations are described by a three-parameter distribution, i.e. with a nonzero location parameter or threshold. On the contrary, the aged populations may be fitted by a simple two-parameter model. A tentative interpretation stating a threshold dependence on aging is proposed on the basis of previous results