Lightning Protection of Electric Power Overhead Distribution Lines by Long-Flashover Arresters in Russia

A simple and effective method for lightning protection of power overhead distribution lines by long flashover arresters (LFAs) is presented. Even large lightning currents do not pose any threat to these arresters because the discharge develops in the air and not inside the device. LFAs, which are based on the creeping discharge effect, increase the lightning flashover length significantly and thus eliminate Power Arc Follow (PAF). To protect a line against induced overvoltages, a single arrester should be mounted on a pole. To protect a line against direct lightning strokes, LFA-M arresters should be mounted in parallel with each insulator. For covered-conductor overhead lines (CCL) using conductors with three-layer insulation a new lightning protection approach is suggested, involving use of antenna-type long flashover arresters whose essential component is the protected conductor itself. The essence of antennatype long flashover arresters (LFA-A) is that the arrester which is connected to the antenna gets flashed over well before the lightning leader comes in immediate contact with the line. The toroid-shaped antenna made of a metal tube is mounted on the covered conductor’s surface midway between the protector’s edge and the piercing clamp with the help of the toroid fixation unit. As the lightning leader progresses from a thunderstorm cloud to the CCL a high potential gets induced on the LFA antenna. A voltage drop that develops between the electrode and the zero-potential conductor core gives rise to development of a creeping discharge. Even before the lightning leader hits the line the creeping discharge channel flashes over the covered conductor’s surface Thereby the conductor insulation get bypassed by the discharge channel and thus protected against puncture. LFA’s main applications and field experience are presented

Lightning Protection of Electric Power Overhead Distribution Lines by Long-Flashover Arresters in Russia

A simple and effective method for lightning protection of power overhead distribution lines by long flashover arresters (LFAs) is presented. Even large lightning currents do not pose any threat to these arresters because the discharge develops in the air and not inside the device. LFAs, which are based on the creeping discharge effect, increase the lightning flashover length significantly and thus eliminate Power Arc Follow (PAF). To protect a line against induced overvoltages, a single arrester should be mounted on a pole. To protect a line against direct lightning strokes, LFA-M arresters should be mounted in parallel with each insulator. For covered-conductor overhead lines (CCL) using conductors with three-layer insulation a new lightning protection approach is suggested, involving use of antenna-type long flashover arresters whose essential component is the protected conductor itself. The essence of antennatype long flashover arresters (LFA-A) is that the arrester which is connected to the antenna gets flashed over well before the lightning leader comes in immediate contact with the line. The toroid-shaped antenna made of a metal tube is mounted on the covered conductor’s surface midway between the protector’s edge and the piercing clamp with the help of the toroid fixation unit. As the lightning leader progresses from a thunderstorm cloud to the CCL a high potential gets induced on the LFA antenna. A voltage drop that develops between the electrode and the zero-potential conductor core gives rise to development of a creeping discharge. Even before the lightning leader hits the line the creeping discharge channel flashes over the covered conductor’s surface Thereby the conductor insulation get bypassed by the discharge channel and thus protected against puncture. LFA’s main applications and field experience are presented

Statistical Characterization of Lightning Induced Overvoltage Waveforms in Overhead Lines

The proper insulation coordination of power apparatuses requires the knowledge of the withstand capability of the insulation against overvoltages stressing the given apparatus. By using a multivariate Monte Carlo procedure and the parameter probability distributions of the Cigr\ue9 waveforms of the lightning current at the channel base, we provide a characterization of the parameter distributions of the induced voltage waveforms in a single conductor overhead line. A simplified formula is proposed to reproduce the curve that represents the expected annual number of lightning that induce voltages larger than the insulation level of the line in case insulators flashovers are not considered in the appraisal. The results for the case of an ideal insulation level are compared to those obtained by considering the flashovers in medium voltage insulators represented by means of the disruptive effect (DE) criterion. The parameters of the DE model are estimated by using the voltage-time-to-breakdown curve inferred from laboratory test results