A Review of System Grounding Methods and Zero Sequence Current Sources

The purpose of this paper is to provide a tutorial or "refresher" on grounding methods, sources of ground current, ground current flow in the power system, and how each impacts protective relaying. With retirements, new hires, reorganization, cross training, and so on, this subject, like many others, requires regular review to maintain the experience level of our protection engineers and we trust that the authors accomplished this task.