An explanation for the decline in URD cable failures and associated nonhomogeneous Poisson process

The possible need to remove from service approximately 2000 miles of high molecular weight polyethylene URD cable has been a topic of concern at American Electric Power. Earlier projections indicated that failures would increase at an exponential rate and that a typical section of cable would be replaced prior to reaching 30 years of age. However, data analysis shows a downward trend in failures after a cable system has been operating for about 18 years. A possible explanation for this finding is the elimination of cable defects through the failure repair (splicing) process. The authors´ findings suggest that, in addition to age and failure history, the decision to remove a cable section from service should be based on the condition of the cable after repair