Long-term mechanical life testing of polymeric post insulators for distribution and a comparison to porcelain

Results and analyses of long-term cantilever strength tests on polymeric post insulators are reported. The time-to-failure data for static cantilever loads are represented by the Weibull distribution. The life distribution, obtained from the maximum-likelihood estimates of the accelerated failure times, fits an exponential model. An extrapolation of the life distribution to normal loads provides an estimate of the strength rating and mechanical equivalence to porcelain line post insulators