Grounding protection studying Substations in Industrial Zones – Insights, Innovations, and Challenges

In the development of a grounding system for a high, extra high voltage substation or any

FACTS or HVDC system, several situations may arise that may facilitate or, by other hand, greatly complicate the design of the grounding grid. One of them is a correct ground resistivity measurement as stipulated in the international standard IEEE 81 “IEEE Guide for

Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Grounding

System”. After ensuring a correct measurement of the ground resistivity, an analysis of the characteristics of the soil where the grounding grid is going to be built is made. The area available for the substation is also a critical parameter in the design of a grounding system, since, as shown in the standard, the grounding system must be designed in such a way as to ensure a reliable, safe and economical design, As shown in the IEEE 80 “IEEE Guide for

Safety in AC Substation Grounding” the resistance of the grounding grid Rg is inversely proportional to the area “A” defined by the perimeter of the grounding system conductor, for a smaller area the resistance will be higher, this is a critical parameter to fulfill with depending on the regulations and standards to which the design must be governed.

The most critical cases occur in substations that are located in industrial areas, where the area is reduced and the soil resistivity is bad, factories can represent internal risks with flammable materials and especially, the validation of touch and step voltages becomes critical in these cases, where there are existing enclosures parallel to the enclosures projected for the new substation and the metal-to-metal touch voltages must be validated, which become critical in this type of designs.