Effective management of earth potential rise through alternative installation strategies for counterpoise conductors

Abstract

Earthing systems must be designed to provide adequate performance and safety for the life of the asset. However, a major issue encountered with older substations in Australia is where MEN encroachment related voltage hazards occur. Touch voltages between the substation EPR and the relatively low potential of the encroaching MEN are difficult to correct with traditional earthing methods. Newer substations can also incur such encroachments, particularly when established in rural growth areas. Earthing designs under such circumstances may therefore be required to be dynamic and scalable. This paper presents two case studies in which the innovative use of the oft-thought traditional counterpoise conductor has contributed to effective management of EPR through a number of stages of development of the substation and surrounding infrastructure. The paper will focus on utilising counterpoise conductors in the management of EPR at both `Brownfield' and `Greenfield' substations by considering transfer hazards, touch voltage hazards, compliance with telecommunications assets and commonly ignored mutual coupling benefits between fault current carrying conductors and the counterpoise. The issues, concepts and opportunities discussed may offer additional strategies to those from various industries with a role in either the detailed design, commissioning testing and specification and ongoing management of earthing systems.