Characterization of Aged PVC Coating for Electric Cables

Some aged cables used in the control circuits of a power plant and the “green fluid” discharged from their polyvinyl chloride (PVC) coatings were characterized by dielectric relaxation, nuclear magnetic resonance, and infrared spectroscopy. The chemical composition of the discharged fluid was determined to contain segments of PVC, PVC/polyvinylacetate (PVAC) copolymer, ester fillers, and <1% copper dissolved to present the green color. The electrical conductivity of the “green fluid” was found to be lower than 10−12 S/cm, falling in the same range as virgin PVC. The dielectric relaxation analysis confirmed the chemical structure results and further revealed that the dielectric properties of the aged cables were little changed as compared to those of the normal.