A study on the origin of space charge accumulation in polymeric HVDC cables

The paper covers results from a study aimed to elucidate the underlying mechanisms behind accumulation of space charge in polymeric high voltage direct current (HVDC) cables. It was observed that the charges in cable samples were mainly located in the outer part of the insulation while space charge profiles obtained on plaque specimens showed almost symmetrical shapes. In both cables and plaques hetero-charge accumulation was the dominant process. The performed experiments include space charge measurements using a pulsed electro-acoustic (PEA) system on cables with and without outer semi-conductive layer. The results suggest that the migration of polar species from the semi-conductive layers is not a prerequisite for space charge accumulation.