Nh. Turner et Am. Bruning, ANALYSIS OF ELECTRICAL INSULATOR SURFACES BY X-RAY PHOTOELECTRON-SPECTROSCOPY, IEEE transactions on dielectrics and electrical insulation, 2(6), 1995, pp. 1140-1146
Our earlier studies centered on understanding the incipient failure me
chanism in polyethylene (PE) as an insulation material. The results si
mulated conditions not measured in routine manufacturing or electric u
tility test procedures. These findings indicated that detectable chang
es with pure PE can occur on the surface of cavities (artificially pro
duced), as observed by X-ray photoelectron spectroscopy (XPS). Because
the prior studies were done with pure PE and cavities that were made
for easy XPS analysis, the question remained ''would the findings from
the earlier inquiry be relevant to materials used by the electrical u
tilities?'' To answer this question PE insulation was analysed from a
series of commercial type cables that had undergone long-term testing.
Occasionally oxygen was found by XPS on the interior surfaces of the
more highly stressed PE cable samples. The estimated amount of oxygen
was lower than that often found previously. The oxygenated carbon spec
ies were similar to those found previously, i.e., alcohols and/or ethe
rs and carbonyls. Some outgassing, probably hydrocarbons, of the PE wa
s observed. The role, if any, of these outgassing components on the fa
ilure of PE as an insulation material is unclear.