The grounding of the supports determines the resistive, the most significant component of the overvoltage acting on the insulation gap between the lightning rod and the equipment of the electrical substation when lightning strikes the lightning rod. (Research purpose) The research purpose is in developing recommendations for the grounding devices for lightning rod supports and means of suppressing sliding spark channels in a multi-wire system. (Materials and methods) The estimation of the share of lightning current in the grounding conductor of the lightning rod support can be calculated simplistically. This makes it possible to abandon the solution of long-line wave equations and switch to a substitution scheme with concentrated parameters, in which the active and inductive resistances of sections of an electric circuit loaded with lightning current should be considered, with mandatory consideration of inductive connections between them. (Results and discussion) The article presents the calculation for a pulse with an oblique front and a flat head, which is traditionally used to estimate the number of reverse overlaps on an overhead power transmission line when a lightning strike hit a support. It was assumed that the lightning strike occurred in the extreme thunderstorm, the current load mode of which is the least favorable. The greatest current load of the grounding conductor of the support corresponds to a direct lightning strike, when the current amplitude there differs from the current amplitude of the first component in the lightning channel by no more than 25 percent, this mode should be taken as the calculated one when estimating the maximum length of the sliding spark channel. (Conclusions) The maximum lengths of sliding spark channels in soils of different conductivity were determined using computer modeling of an emergency situation of a lightning strike, provided that the reinforced concrete foundations of the lightning rod supports connected by an underground horizontal bus are used as grounding conductors of lightning rods. The most effective means of limiting the danger of sliding spark channels is their forced orientation to the side, which is safe for the grounding circuit of an electric substation.

The article presents the results of theoretical calculating the parameters of a corona discharge when protecting the territory of substations from direct lightning strikes using multi-drop lightning protection. The parameters of the corona discharge are important when calculating the energy losses in the wires of overhead power lines in bad weather. (Research purpose) The research purpose is in developing a computational model and analyze the processes of lightning protection of a substation by placing parallel grounded cables suspended on supports that are placed outside the substation territory. (Materials and methods) The solution is based on a well-known relation for a typical dipole model of a charged thundercloud cell. (Results and discussion) The article present the calculated theoretical dependences, mathematical formulation and algorithm for numerical calculation of the two-dimensional problem that form the basis for calculating multi-wire lightning protection, as well as the calculation results of cable lightning protection of a transformer substation based on two-dimensional numerical modeling and comparison of the results of calculations using analytical expressions with the results of two-dimensional numerical modeling. Despite the noticeable difference between the limit currents calculated by different methods, the difference between the average current between them is small compared to the currents themselves, so one can use its arithmetic mean to determine the actual current. (Conclusions) The obtained results allow to take into account changes in the parameters of the corona formed in the electric field of a thundercloud along its cable length due to its sag, since such changes in the input parameters have a noticeable effect on the corona process, in some cases it is more significant than the effect associated with the actual sag of the cables.