An overview of aging mechanisms and diagnostics for extruded power cables

Distribution- and transmission-class cable systems represent a large capital investment for electrical utilities and have to be highly reliable to avoid lost revenues resulting from premature failure. Deregulation will increase pressure to cut costs and cause transmission systems to operate closer to, or even exceed their maximum limits in the future. As a result electrical utilities are now being faced with decisions to maintain, repair, refurbish, or replace their cable systems. To do this requires knowledge of the condition of cable systems by understanding the aging mechanisms and the development of diagnostic tests to assess the aging. The paper describes the main aging and failure mechanisms of extruded cable systems used in transmission cables, usually dry insulation, and distribution cables, usually wet insulation. The advantages and limitations of diagnostic tests are included