A review on testing and evaluating substation grounding systems

A systematic approach of testing and modeling grounding system performance of large multi-grounded power stations is described. Simple and detailed test methods using 65-70 Hz current injection are explained. A simple model including distribution neutrals and shielding factors has been developed to validate measurements and is based on hand calculations. The testing and modeling procedure has been successfully used at more than 20 Ontario Hydro stations spanning a period of more than a decade. Results at one transformer substation are presented as an example