Problems Encountered With The Average Potential Method of Analyzing Substation Grounding Systems

This paper describes some problems which can be encountered when using the average potential method to analyze sub- station grounding systems. Several examples are shown which illustrate how some of the assumptions made in developing the average potential method affect the accuracy of the results. The sources of error in some of these assumptions are explored. The paper concludes that caution should be exercised in interpreting the results of this analysis technique and suggests further research to determine the error to be expected and/or corrections to the method.