A substation grounding system is an important part of any electrical system since it allows dissipating of electric current to the ground and also ensures personnel near or using an electrical equipment don’t suffer from dangers of electric shock.
A substation grounding system is comprised of all interconnected grounding equipment in the substation area which include ground grid, neutral conductors, overhead ground wires, foundations, underground cables, deep well, etc.
A substation ground resistance which is low is not a safety guarantee and no simple relation has been found between resistance of a grounding system in totality and the highest shock current which a person can be exposed to. A relatively low ground resistance in a substation could be dangerous while one with high ground resistance could be safe due to careful design.
Voltages are site-dependent and it is impossible designing a grounding system acceptable for every location. The voltage in and around a grounding substation area is affected by soil resistivity, fault duration, grid current, surface material, shape and size of the grid.