Assessment of water logged cables by very low frequency tan delta testing technique

Distribution cables rated 22 kV which were submerged under water for more than 45 days due to flash floods in one of the processing industry were assessed using VLF technique in addition to other techniques like insulation resistance and dc voltage withstand test. Special technique used for extraction of water from the cable termination is discussed. The consequences of bad crimping of cable lugs and improper cable terminations on the penetration of water into the cable length are highlighted. The study showed abnormal dielectric losses in the cable insulation as a result of highly polar contaminants in the cable. The precaution to prevent water entry into the cable are suggested in this paper.