Effects of deteriorated and contaminated substation surface covering layers on foot resistance calculations

摘要

It is shown that significant inaccuracies can occur when the ANSI/IEEE Std 80 method for calculating foot resistances is applied in substations covered by a thin layer of crushed rock or similar covering layers. In particular, the errors obtained by using the infinite series expression of the foot resistance are consistently larger than those produced by the simplified expression for clean and contaminated surface layers.