• The investigation of frequency impact on XLPE
cable is very complicated process in terms of
experiment setup, material, testing tools and results
monitoring. Although such work needs specialized
laboratories of international scale, the achieved
results are of great importance.
• Increasing of harmonics level in power grid is highly
affecting the expansion of electrical tree in XLPE
insulation of power cables. This is attributed to the
intensive partial discharges and photo ionization
occurring at high frequency.
• The initiation mechanism of electrical tree is the
same at all applied frequencies. This is strongly
related to electron injection and extraction at the
needle electrode due to the high electric field. Part of
the insulation in the front of needle is deteriorated by
this process. This is followed by an intensive partial
discharge and photo-ionization due to charge
recombination in the channel of the tree. The
continuous micro-breakdown at the tree tips and the
electron avalanche mechanisms play a great role in
this process.
• Material morphology is less dependent on high
frequency harmonics.