An Analytical Procedure to Identify a Global Earthing System

Global Earthing System (GES) is defined by international standards IEC 61936-1 and EN 50522 as an equivalent Earthing System (ES) created by the interconnection of local ESs. Thanks to this interconnection, just a percentage of the total fault current is injected to ground in a single ES, with a significantly reduction of touch voltages in case of fault. If a GES is officially certified, the procedure to verify the effectiveness of an ES can be simplified, with advantages in terms of time and money. Unfortunately, Standards do not provide any practical guidelines to identify a GES. In this work, a methodology is proposed for MV network with the neutral point isolated from ground. A practical example is provided.