A survey of URD cable installed on rural electric systems and failures of that cable

Abstract

Several surveys have been conducted with the purpose of determining the history of failure of underground power cables. Typically, these surveys are used to compare data related to cables of various types or installation conditions. The Rural Electrification Administration (REA) has determined that most of the studies have not supplied valid or meaningful information, because neither the vintage of the cables nor their age at failure was considered. In 1988 and 1989, REA conducted a survey which supplied results which are both valid and meaningful. Analysis of the data reported by over 100 rural electrical cooperatives revealed trends related to several variables, such as insulation material and thickness, jacketing, conductor type, and installation methods. The cumulative total of failures, to date, of the cable installed in each year since 1970 was calculated and broken down according to the same variables. The results of the survey are discussed, and recommendations concerning ways that electric utilities can effectively use the results in considering replacement of aged cables are presented.<>