A Comparative Review of the Methodologies to Identify a Global Earthing System

International Standards IEC 61936-1 and EN 50522 define a global earthing system (GES) as the earthing network, created by the interconnection of local earthing systems that should guarantee the absence of dangerous touch voltages. Despite that, standards do not provide any official practical guidelines for its identification. The official classification of GES areas would lead to a simplification of the design and verification procedures of medium voltage/low voltage (MV/LV) substations grounding systems with associated economical savings for both distribution system operators and MV users. To overcome this regulatory vacuum, several teams of researchers proposed methods to identify the presence of a GES. In this paper, the main methods developed to identify a GES are presented. The different methodologies are applied to a real urban scenario and compared.