Transient Ground Potential Rise in Gas Insulated Substations - Assessment of Shock Hazard

Breakdowns and disconnect switch operations in gas insulated switchgear (GIS) generate short duration high potentials on the grounded GIS enclosures. These high potentials cause breakdowns between the GIS enclosures and other nearby grounded components, and have resulted in low voltage protection and control wiring failures and personnel shocks. The mechanism of the transient ground rise phenomenon and the equipment related problems are discussed in two companion papers. The question of the degree of personnel shock hazard imposed by transient ground rise is discussed in this paper. The physiological effects of short duration impulses are reviewed and it is concluded that further biomedical research is required.