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Typical towers of the 150 kV and 400 kV double-circuit overhead lines of the Hellenic transmission system.
Source publication
Estimation of the minimum lightning current causing backflashover of line insulation is of great importance for the calculation of the backflashover rate of overhead transmission lines. The minimum backflashover current can be estimated through simplified expressions or, more accurately, through computer simulations. The latter allow for the detail...
Contexts in source publication
Context 1
... addition, as a result of a decreasing IBF, BFR increases with R0 tending to asymptotes at relatively high R0 values. This dependence is less pronounced when BFR is estimated according to (13) than (9). Fig. 11 shows a comparison between the results of expressions (9) and (13); the latter yields higher BFR, especially as R0 decreases and when considering soil ionization due to a higher IBF. These deviations are intensified for the 400 kV overhead transmission line. Power frequency ground resistance, R 0 ...
Context 2
... backflashover rate of the 150 kV and 400 kV overhead lines is calculated using the minimum backflashover current estimates obtained through simulations. For BFR calculations a new expression is proposed; results are compared and discussed with those obtained using the traditional BFR expression of CIGRE [2]. Fig. 1 shows typical transmission towers of the 150 kV and 400 kV double-circuit overhead lines of the Hellenic transmission system employed in ATP-EMTP [6], [7] simulations; line characteristics are given in Table ...
Context 3
... (9) and (13) the BFR of the evaluated overhead transmission lines was calculated as the average of the BFR values corresponding to each phase angle of the power frequency voltage of the line, in accordance with [3], by considering the corresponding IBF estimates obtained from simulations. Fig. 10 shows the variation of BFR with power frequency ground resistance by neglecting or considering the effects of soil ionization on tower impulse ground resistance. In the former case the BFR estimates are on the safe side due to a lower IBF (Figs. 5 and ...
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