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This paper presents preliminary results related to the impulse breakdown characteristics of XLPE-covered cables. Tests with standard lightning impulse voltages (1.2/50 μs) applied to a typical single-phase structure employed in compact distribution lines used in Brazil were performed. Results in terms of breakdown voltage, time to breakdown and pinhole location are presented.
This work presents a discussion on the traditional methodologies presented by CIGRE and IEEE to calculate the lightning outage rate of high voltage transmission lines in terms of backflashover occurrence. The main aspects of such methodologies are reviewed. The simplifications and approximations adopted to determine the outage rate are discussed. Systematic simulations are developed considering a...
This work aims to discuss the impact of considering the soil ionization effect on evaluations of the lightning performance of transmission lines, in terms of backflashover occurrence. The representation of this effect is considered by means of a methodology that assumes the increase of the electrode equivalent radius. Computational simulations using the Hybrid Electromagnetic Model were developed...
The Hybrid Electromagnetic Model was used systematically to determine lightning overvoltages across insulator strings due to direct strikes to the tower top in order to assess the importance of subsequent strokes on backflashovers for 138-kV transmission lines. It was found that for some specific conditions, especially for lines with high towers and low tower-footing grounding resistances, subsequent...
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