Since the early days of the electric power industry, the safety of personnel in and around electric power installations has been a primary concern. With ever increasing short-circuit powers and, thus, fault current levels in today typically interconnected power systems, there is a suitable renewed emphasis on safety.
The safety of people may be compromised by the rise in the ground potential of grounded structures during unbalanced electric power faults. In such conditions, humans touching grounded structures can be subjected to high voltages.
Safe operation of electrical installments calls for a properly designed and installed earthing and grounding system, in order to ensure that the magnitude and duration of the electric current conducted through body are not sufficient to cause ventricular fibrillation.
In general terms, and for substations in particular, a proper grounding path of low impedance ensures low potential rise and also a fast clearing time for faults (a fault remaining for long within a system may cause several critical issues, including those related with power system stability. Thus, faster clearing improves overall reliability, more than ensures better safety, because any person coming into contact with available metallic parts and/or metallic enclosures is exposed to higher risk increasing potentials and fault durations).
Here attached a small introduction to grounding system design, especially following IEEE std 80.
Moreover I attach the link for downloading a pdf copy of the MILITARY HANDBOOK - GROUNDING, BONDING AND SHIELDING FOR ELECTRONIC EQUIPMENTS AND FACILITIES from which some interesting concepts can be added to those included in the std80.
This last document should be copyright free[link Point to another website Only the registered members can access]
I will try to complete the measurements section and, possibly, prepare some worksheet for simple calculations.
Regards,
hope this can be of use for someone,
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