PD inception characteristics of polypropylene laminated paper/liquid nitrogen composite insulation system under local heating

A high-Tc superconducting (HTS) power cable is one of the major candidates for reinforcing power transmission grids dynamically. For operation of the HTS cable, a quench phenomenon would occur due to over-current operation, degradation of the HTS materials, and so forth. In that case, local heating would occur and local evaporation of liquid nitrogen would occur, which may lead reduction of the electrical insulation capability and generate partial discharge (PD) under operational voltage application. This paper deals PD inception characteristics with local heating simulating local quench of HTS material. As a result, it is revealed that there is a time delay from the start of heating to PD generation, and the delay depends on the pressure of liquid nitrogen.