Estimation of electric field force density in water-treed XLPE insulation under variable frequency AC Voltage

Water-tree behavior have been investigated for 400kV cross-linked polyethylene using water needle method by applying variable frequency AC voltages. The microstructure shape of water-trees along with interconnected channels are simulated by finite element analysis. A comparison for different state of water-tree channel model is implemented with 50 Hz, 400 Hz and 3 kHz frequency cycles, demonstrates the calculation of electric field force density. It has been concluded that the influence of ion concentration in water-filled channel region collide with micro voids at high frequency cycles. With increased permittivity, it is noticed that force density increases monotonically in 50Hz and 400Hz frequency cycles, while it behaves nearly linear for 3 kHz.