A Study on the Degradation of Dielectric Characteristics of Polypropylene for an Eco-friendly Power Cable according to White Rust

Cross linked polyethylene (XLPE) has been widely used for power cables as an insulation material due to its excellent dielectric and mechanical characteristics. However, XLPE can not be recycled after the lifetime of power cables because of its thermosetting property. In many countries, power cables have been developed and installed actively since 1970. It means that the lifetime of power cables is reaching over 50 years. It is known that the lifetime of power cables is around 50 years. Therefore, many power cables in a power grid installed in 1970s should be replaced with new power cables in order to improve the reliability of a power system. In this replacement, there are many studies to change thermosetting materials, XLPE into thermoplastic materials, polypropylene (PP) which can be recycled. This paper deals with the analysis on the dielectric degradation characteristics of PP according to white rust. White rust may occur in power cables due to curvature and scratch which could be caused by bending stress and friction. Especially bending stress is inevitable because of narrow installation area and process of installation. The dielectric degradation characteristics of PP are analyzed under AC as well as lightning impulse voltage test. It is found that the dielectric degradation characteristics of PP according to white rust is more degraded at lightning impulse voltage test than AC voltage test.