Risk assessment of leakage current-based insulation failure
Leakage current has been shown to depend on both the sand’s contamination layer thickness and on its salinity and hence its electrical conductivity. The above two variables were reported to be random and may thus be expressed in statistical terms. Subsequently, the leakage current can also be viewed as a random variable, whose probability density distribution is inevitably a product of the probability density distributions of the pollution layer conductivity and that of the pollution layer thickness, which is – in turn – dictated by the sand grain size.
The two variables, conductivity c and sand grain size g, are reasonably assumed to be statistically independent. If the probability distributions of the conductivity and sand grain size are, respectively, p(c) and p(g), then the probability distribution of leakage current p(I) would be