Abstract: The technical requirements of grounding systems for petrochemical substations are analyzed, and the design methods of equal and unequal spacing arrangement of grounding network are analyzed through case studies, which are verified by calculations and simulation of EDSA software model. It is concluded that, compared with the equal spacing arrangement of traditional grounding network, the unequal spacing arrangement of grounding network results in a more uniform distribution of contact voltage, higher utilization rate of grounding conductor, higher investment savings, and more optimized grounding design for substations.

Key words: grounding, equal spacing, unequal spacing, EDSA