Effect of Electric Field Profile Changes on Partial Discharge Phenomenon in a Loaded HVDC Cable

This paper deals the effect of electric field distribution on the triggering of partial discharge phenomenon in a loaded HVDC model cable. The electric field profiles have been obtained starting from the measurement of space charge accumulation carried out by means of a novel PEA cell. Measurement results show that the electric field distribution along the radial direction of the cable changes during the application of a DC high voltage stress and thermal gradient. In particular, it has been observed that after 20 minutes of the beginning of the test the maximum value of the electric field moves from the inner to the outer dielectric interface. This increment, occurring in correspondence of the cable radius in which a defect is present, reaches the electric field inception of PD.