Safety Compliance of Substation Earthing Design

As new challenges emerge in power electrical workplace safety, it is the responsibility of the systems designer to seek out new approaches and solutions that address them. Design decisions made today will impact cost, safety and serviceability of the installed systems for 40 or 50 years during the useful life for the owner. Studies have shown that this cost is an order of magnitude of 7 to 10 times the installed cost of the power distribution equipment. This paper reviews some aspects of earthing system design in power substation surrounded by residential houses. The electrical potential rise and split factors are discussed and a few recommendations are provided to achieve a safety voltage in the area beyond the boundary of the substation. Keywords—EPR, Split Factor, Earthing Design I. INTRODUCTION HE benefits of electricity are numerous but mishandling it can cause damages to properties and may inflict injuries and fatalities. Electrical management is the key element in human safety, also not underestimating the importance of protection equipment in the wide area of electrical infrastructure can be another added factor in raising the risk factor. Earthing must be the primary concern during the design and operations of electrical infrastructure. People often assume that any grounded object can be safely touched. A low substation ground resistance is not, in itself, a guarantee of safety. Step and Touch voltage need to be assessed in and around the substation boundaries. A serious hazard may result during a ground fault from the transfer of potential between the substation ground grid area and outside locations. This transferred potential may be transmitted by communication circuits, conduits, pipes, metallic fences, low0 voltage neutral wires, etc. The danger is usually from contact of the touch type. An investigation into possible transferred potential hazards is essential in the design of a safe substation grounding network. This paper discusses the management of earthing system design to meet the safety requirements as per the Australian and IEEE standards. In addition this paper investigates the area of concerns when dealing with the earthing system and what factors should be taken into when reviewing the design