The aim of the presented work was to examine the reliability assessment model on the example of a selected power grid object. The analyzed object was tested based on assumptions about technological breaks that were caused by overvoltage, among others. The study was conducted to check the reliability of integral elements of the power grid object and to assess the change in reliability level as a function of the frequency of inspections. The test results are to determine the optimal frequency of inspections of individual power grid objects in order to increase its reliability. In addition, the possibility of correlating optimal inspection periods resulting from the findings of this paper with periodic inspections of power network facilities was assessed.

The paper aims to analyze the parameters of prototypes of new overvoltage protection devices for power grids—a multi-chamber insulator arrester (MCA) and a long flashover arrester (LFA). The article presents the research results on determining the actual MCA and LFA impact characteristics. Moreover, the results were compared to assess the effectiveness of the overvoltage protection devices. The research results presented in this article will supplement missing information about the devices. They will make it possible to evaluate the possibility of using overvoltage protection devices for a new type of spark gap based on a multi-segment system in high-voltage networks of a specific country. The analysis of its properties against the background of atmospheric overvoltages and their impact on high voltage lines will be carried out by assessing the effectiveness of the tested overvoltage protection device in laboratory conditions. The tests will also be carried out by applying standardized lightning and switching surges to the tested device to map the overvoltage processes on the power grid elements. Two different generators will be used for this purpose. The proposed research will also allow learning about the influence of structural elements on the operation of the tested devices.

Long linear antennas for very low frequency radio transmissions, supported by aerostats, unanchored, and raised to high altitudes, present themselves as slow-moving, highly conductive disturbances in cloud layers, acquiring an electrical charge and being subjected to intense coronae. High electric field strength values around those objects increase the risk of lightning strikes, which could be disastrous to the mechanical structures of the balloon mission (both the antenna and the balloon) and the radio transmitter. This paper aims to investigate the inception of lightning strikes over two essential elements of such missions: a talc-covered latex (balloon material) and the model of the linear antenna, made of different materials. Based on the high-voltage experiments with the recorded electrical discharges, the properties, functions, and possible ameliorations of the talc cover are presented, as well as the basic characteristics of lightning forms around the very long antenna system, with a proposition of design requirements and constraints reflecting the safety of the balloon missions employing a VLF antenna from lightning strikes.

Grounding is one of the key elements ensuring the reliable operation of overhead lines. The purpose of this paper is to provide a comprehensive assessment of grounding using a 400 kV overhead line as an example. The paper presents the results of diagnostic grounding measurements of various types of 400 kV overhead line poles, performed according to technical documentation and taking into account local terrain characteristics. The paper examines a large number of overhead line poles in both uniform and varied terrains, taking into account soil conditions based on geotechnical documentation. Furthermore, the paper presents a simulation analysis of lightning current dissipation through the grounding of a selected pole, taking into account geotechnical soil investigations with respect to soil stratification. The final section of the paper includes guidelines on grounding and assessment of the technical condition of grounding systems, which may be useful to transmission and distribution network operators.