Investigation of the breakdown characteristic of LDPE including cumylalcohol under DC high electric field

Space charge accumulation and conduction current in low density polyethylene (LDPE) incuding cumylalcohol under dc high electric field were investigated using improve PEA (pulsed electro-acoustic) measurement system. In the bulk of XLPE that is being used for power transmission cables, there remain some chemical residues of crosslinking by-products such as α-methylstyrene, acetophenone and cumylalcohol. Such residues are assumed to affect the space charge formation and the increase of the conduction current followed by the breakdown. Especially, cumylalcohol seems to remain in XLPE for long time even in thin test film because it is non-volatile at room temperature. Therefore, several kinds of research about the effect of cumylalcohol on the space charge behaviors in LDPE have been carried out. To elucidate the breakdown mechanism in the sample, we measured the space charge density distribution and the external current simultaneously using the improved PEA measurement system. Moreover, we discussed the process of the breakdown based on the conduction current and dissipation energy distributions which are calculated from the measurement results.