Lightning overvoltages of lighthouse electrical systems and protection methods

The issue of lightning protection of the electrical systems of lighthouses located in Russia is being considered. The lightning strike calculation is based on the theory of lightning formation – a leader discharge: a low-temperature plasma channel is considered, in which the leader head at the end of the lightning carries a charge until it is short-circuited to earth or a lightning rod. A leader discharge is a “streamer”, a pretrial stage of an electric discharge, a channel of a leader charge. Lightning formation is completed by the main discharge, which in turn changes the direction of the electromotive force in the lightning channel. The materials of statistical observations of lightning formation, as well as studies of various sources, are collected and analyzed. The problem of overvoltage in lighthouse electrical systems related to the high resistivity of the ground, as well as the electromagnetic component of a lightning strike, is considered. To find a full-wave solution to Maxwell's equations, the FIDELITY simulator program based on LS-FDTD was used. It is noted that the discharge intensity and current amplitude depend not only on the ground resistance, but also on the frequency of the lightning current. The result of the calculation of overvoltages, which can lead to the failure of the lighthouse electrical systems, is presented. An example of installing a lighthouse in an area with soil having a high resistivity, which in turn does not allow the use of classical grounding systems, is given. At the calculation stage, an answer was received about the propagation distance of the dangerous voltage for the beacon systems. Variants of a non-standard design solution for the lightning removal system are proposed, which is optimally suited for the task at hand – reducing the resistance of the grounding conductor.