Self-repairing secondary underground residential distribution cable. I. Design and testing

In the past, costs associated with repairing secondary URD cables, while not acceptable, were not viewed as a serious enough problem to warrant attention. In an effort to reduce operating costs and to provide customers with uninterrupted service, electrical utilities are taking a fresh look at secondary failures. The main mechanism of failure has been corrosion of the aluminum conductor once the electrical insulation has been breached. For this reason, new designs have been developed to prevent conductor corrosion by limiting the conductor exposure to the environment. "Self-Repairing" cable has been designed with a viscous but flowable elastomer situated within the cable to effectively seal the site should damage occur and continue to provide reliable service. Extensive laboratory and field testing has shown leakage currents greatly decrease or even fall to zero after the insulation breach. Voltage breakdown testing on cable which has self-repaired, demonstrate fully appropriate retention of dielectric strength.