Investigation in to growth of electrical trees in XLPE cables under transient voltages

The problem of development of electrical trees under transient voltage profiles is discussed including the methods of generating the experimental database. The physico-chemical changes in the treed zone are analyzed using the wide angle X-ray diffraction (WAXD) and through Fourier transform infrared spectroscopy (FTIR) analysis, which gives clear emphasis that the tree propagation causes degradation in the zone forming different structural composition. It is observed that the tree inception voltage is less under oscillatory impulse voltages (OIV) compared to the SI voltages, and much less under sine-bidirectional oscillatory impulse voltages (SBOIV) compared to unidirectional oscillatory impulse voltages (UOIV).