Transmission Line and Substation Insulators Asset Health and Preventive Maintenance

This paper presents a new technique to assess, display and prioritize maintenance on energized insulators in substations. The technique is based on the proven Electric field (E-field) method used on overhead Porcelain and Composite suspension insulators. This method measures the E-field distribution along insulators, detects, displays and records defects, their severity and location of any internal or external conductive defects. The results are stored in a database to enable a full overview of the T&D assets. It is also used to show degradation over time for maintenance prioritization and to assess reliability. This technology is now used for both, the suspension insulators found on transmission lines and the insulators/bushings found in substations. An overview of some of the most frequent defects obtained over the years on Porcelain and Composite suspension insulators is presented, followed by new examples of defective insulators found in substations. Defects include punctured or leaking discs, connected and floating defects caused by moisture ingress, carbon tracking, manufacturing defects, etc. The E-field methodology is safe to use and makes no electrical/metallic contact with the insulator. It immediately alerts workers of a dangerous situation. It is used for maintenance purposes and as a safety tool.