Who is this course for?
For engineers and consultants who want to learn more about measuring tower footing resistances. A basic level of electrical engineering knowledge is recommended.
Module A12
After following this course you will be an expert on the topic of tower footing resistance and tower footing impedance, of towers in an overhead line. The theory for low frequency and high frequency behaviour is treated in different sections. This online course provides detailed descriptions of the different methods (such as the Fall of Potential method) to measure the tower footing resistance (in low frequency) and impedance (at higher frequencies). The advantages and disadvantages are explained and some examples are presented to get some experience.
Some simple tools are provided to estimate values through calculations and perform an analysis of measurement results. At the end of the module your knowledge will be tested. What you should know is that only the questions in the final chapter (“Test your knowledge”) are used for grading your final score. All other questions are for feedback and learning purpose only. In order to finish the course successfully, all modules shall be graded 70% or higher. Then, at the end of the course you will receive a certificate.
Tools
Three simple excel tools are made available; The first tool can be used to calculate the earthing resistance of a tower, using the geometric and contact resistance method. The two other tools help with the interpretation of measurements on towers: one for the Fall of potential method and the other for the Oblique probe method.
Update: as per 2025 we are also offering web-based tools via our ‘tools-page‘.
Other
Prerequisites for the use of the excel-tools: Microsoft Office Excel shall be installed with the option to run VBA macro’s. If you want to extend or change the tool you are free to do so. This is easy if you have experience with Excel. Prerequisites for the use of the web-based tools: a recent browser (such as Chrome or Edge) supporting Javascript.
References: this module refers to the EPRI Guide for transmission line grounding (Grounding guide), Cigre technical brochure 781 and other documents.
Key words: Overhead line; tower; transmission; distribution; tower footing impedance; tower footing resistance; measurement; low frequency; high frequency; fall of potential method; oblique method; impulse method; soil resistivity
