This paper presents a comprehensive assessment of the accuracy of high-frequency (HF) earth meters in measuring the tower-footing ground resistance of transmission line structures, combining simulation and experimental results. The findings demonstrate that HF earth meters reliably estimate the harmonic grounding impedance (R25kHz) at their operating frequency, typically 25 kHz, for a wide range of soil resistivities and typical span lengths. For the analyzed tower geometries, the simulations indicate that accurate measurements are obtained for adjacent span lengths of approximately 300 m and 400 m, corresponding to configurations with one and two shield wires, respectively. Acceptable errors below 10% are observed for span lengths exceeding 200 m and 300 m under the same conditions. While the measured R25kHz does not directly represent the resistance at the industrial frequency, it provides a meaningful measure of the grounding system's impedance, enabling condition monitoring and the evaluation of seasonal or event-related impacts, such as damage after outages. Furthermore, the industrial frequency resistance can be estimated through an inversion process using an electromagnetic model and knowing the geometry of the grounding electrodes. Overall, the results suggest that HF earth meters, when correctly applied with the fall-of-potential method, offer a reliable means to assess the grounding response of high-voltage transmission line structures in most practical scenarios.

The aim of this work is to analyze the effectiveness of Bentonite, Kenaf and Pine Wood mixtures as enhancement materials for grounding system purposes. Grounding systems are designed to dissipate high-magnitude fault currents to Earth and provide safety to persons working in or living near power system installations. They are also necessary to protect equipment from being damaged caused by lightning strikes. The safety and reliable operation of various applications in an electrical system is highly depending on the effectiveness of the grounding system installed which could be achieved with a low resistance path, and this can be obtained by employing grounding enhancement materials to the surrounding soil of the installation site. Hence, this is highlighted in this work where NEM mixtures grounding systems were installed at a site near to SGS, UPM with a high resistivity soil profile. Kenaf is a natural fiber that has been shown to be effective in improving the performance of grounding systems as it has a high conductivity and a high dielectric constant. This means that it can carry electrical current well and it can also store electrical energy. Kenaf is also a relatively inexpensive material, which makes it a cost-effective option. The unique properties of Bentonite, a clay material, and Pine wood, a natural insulator, make them promising options for improving grounding systems. Six grounding systems were installed with 100% Bentonite, 100% Pine, Bentonite and Pine Mix, Bentonite and Kenaf Mix, Pine and Kenaf Mix, and Reference grounding systems. A comparison was made between them using daily measured earth resistance from 2nd March 2023 until 10th July 2023, i.e. for 130 days. It was found that mixtures of Bentonite and Pine Wood performed better than the 100% Bentonite.