At present, the measure of Tan delta for oil impregnated
kraft paper in PILC cables is only gross measurement by using
very low frequency (VLF) and power frequency in which the
MUT is usually several to tens of meters long of medium
voltage (MV) power cables. These measurements have no way
to determine the localized aging of the insulation material as
the paper is in a form of strip with width and thickness of
about 2.8 cm and tenth of a millimeter only. In order to make
localized measurement in the laboratory, a new sample holder
is needed for the samples. As the dimensions of the samples
are very small hence the high frequency technique to
determine the complex permittivity is more suited as available
equipment such as the network analyzer can be employed for
the measurement at a much lower cost.