Lifetime Estimation of a Tape Lapped Joint for a XLPE Cable

Abstract

EPR tape is employed as the insulator of tape lapped joint (TJ), which is used for 66kV class XLPE cable. It has been found that, in case a TJ is operated at higher than the short-time allowable temperature of XLPE cable (105°C), its EPR tape is oxidized, which may break the tape to lead to dielectric breakdown in the TJ. Therefore, when one operates a XLPE cable at higher than this temperature, it is necessary to catch the degree of oxidation of the EPR tape.
In this research, we have developed a technique to investigate the degree of the oxidation of EPR tape. Oxygen induction time (OIT) observation gives the volume of remaining antioxidant in EPR tape, from which the degree of the oxidation is derived. We investigated the oxidation of EPR tape of the TJ which had been operated at high temperature by this technique. The result shows that the oxidation concentrates to the surroundings of the inner conductor.