Analysis of lightning-induced currents in supply cable shields and their impact on LLS sensor site errors

Abstract. Lightning location system (LLS) sensors, which detect and locate atmospheric discharges, are typically powered by cables buried up to one meter underground. Within the LLS community, it is well known that these cables can create spurious magnetic fields, which can in turn adversely impact the sensor measurements and the resulting data. This issue arises from currents induced in the cable shield by the lightning electromagnetic fields that penetrate the ground. The magnetic field generated by these currents lead to “site errors”, causing inaccuracies in estimating the angle of incidence and the peak current of lightning strokes. Although these sensor-specific errors can be partially corrected, a better understanding of the coupling mechanism between the lightning electromagnetic field and the cable could help in minimizing the site errors. This study presents an analysis of the lightning electromagnetic field interaction with cables and examines the influence of various ground and cable properties on this interaction. This work represents a first step toward understanding the physical mechanism leading to LLS sensor site errors. Considering simplified scenarios involving a single insulated or bare conductor, this work provides practical insights that LLS operators can use to estimate worst-case site errors for a provisioned sensor site. Additionally, we show that some site errors observed in operational sensors can be successfully reproduced with good agreement using the proposed approach.