Scanning with the micro-PIXE technique was employed to analyze water trees
in the XLPE insulation of a field-aged underground Hv cable. X-ray spectra
of bow tie and vented water trees, the inner and outer semiconductive compo
unds, and an insulation spot free from any water tree were acquired. Simult
aneously, two-dimensional elemental distribution profiles across the water
trees were also measured. Various trace element impurities were identified
in the analyzed spots and their possible sources are suggested. Differences
in elemental distribution profiles in the scanned areas were observed and
have been discussed on the basis of the mechanism of incorporation of these
elements into the insulation. This study demonstrates the effectiveness of
: the micro-PIXE facility available in this laboratory in analyzing water t
rees in underground power cables.