Effect of excitation current waveform on PD induced electromagnetic wave propagation and attenuation in straight 154 kV GIS model tank with epoxy spacers

This paper deals with effect of excitation current waveform on PD induced electromagnetic wave propagation and attenuation in straight 154 kV GIS model tank with epoxy spacers. An attempt was made to determine a standard wave shape of experimentally obtained EM wave for the simulated ones obtained by changing the rise time t_r of the excitation waveform of Gaussian pulse from 25 ps to 200 ps with the propagation attenuation in GIS considered. This comparison was performed in terms of both transmission rate T_v of peak to peak value V_pp of EM wave intensity and transmission rate T_w of accumulated energy of the EM wave. The simulation revealed that as t_r is shortened, both T_v and T_w decrease. As a result, it was found that simulated excitation pulse with the rise time of 25-50 ps allows the best fit to experimentally obtained T_v and T_w when the calculation was made for a straight GIS structure with two epoxy spacers for a free metal particle on the tank. Furthermore, the rise time of 25-50 ps for T_v and 100-150 ps for T_w was found to give the best fit to the experimental results for a protrusion on the high voltage conductor.