Study on heating mechanism of GRP rod in a composite insulator

An abnormal temperature rise of the composite insulator, which was reported as the early stage of decay-like fracture of the composite insulator, has drawn the close attention of the operation and maintenance department of the power grid. In this study, the heating mechanism of GRP rod in composite insulator was studied. At first, the current, partial discharge and temperature rise of 30 mm-length short GRP rods were tested in high and low humidity environment. According to the experimental results, the simulation model for the temperature rise of the GRP rod was established. It was proved that the temperature rise was caused by the volume current. At last, the circuit model of the GRP rod was set up and the contribution of polarisation loss and conduction loss to the temperature rise was discussed. It could be concluded that the power of temperature rise of the GRP rods was mainly supplied by polarisation loss and the invasion of moisture was the main reason for the increase of polarisation loss in high humidity. In low humidity environment, both polarisation loss and conduction loss would play an important role in temperature rise and the deterioration of the material was the main reason for the increase of the dielectric loss.