The influence of antioxidants on electrical tree generation in XLPE

Abstract

AbstractIn conjunction with previous experiments studying the effect of decomposition products of dicumyl peroxide (DCP) and antioxidants (AOs) in cross‐linked polyethylene (XLPE) insulation on electrical tree generation, the authors conducted experiments investigating tree inhibition by phenolic AOs. The experiments were conducted using XLPE slabs containing four different phenolic AOs. Among the specimens containing these AOs, the specimen containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) was found to show the highest tree inception voltage. To examine the reasons for the significant increase in tree inception voltage in this specimen, further experiments were carried out on XLPE specimens containing both phenolic AO and a sulfur‐containing AO. The results demonstrated that the tree inception voltages of specimens containing both phenolic AO and sulfur‐containing AO were higher than those of the specimens containing only one of these two types of AOs. The roles of antioxidants in XLPE dielectrics are discussed with reference to the mechanisms of autoxidation of polymeric materials. The great increase in the tree inception voltage of XLPE specimens containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) appears to be due to a synergistic effect between the phenolic AO and the sulfur‐containing AO. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 1–7, 2001