Grounding system-knowledge of soil resistivity

This paper presents techniques important for the design of different grounding systems. Such system can be found in substations, power grids, wind farms, hydropower plants etc. Grounding system can have a lot of reasons of what they are supposed to fulfil. Often it could be a combination of many things. Even if that is the case, a main purpose must be clearly defined and controlled. The main objective for designing a good grounding system is often one of three: personal safety; lightning protection; or functional grounding systems. If we focus on personal safety the step and touch voltage are the main issues. Design of grounding system is dependent of current, soil resistivity, area and proximity to other existing grounding system. Soil resistivity is the factor where electric power engineers have least knowledge. And it is a factor which is difficult to change.