This working group seeks the definition of innovative criteria for the design and safety analysis of electrical earthing grids, based on risk analysis.
Currently, an earthing grids safety analysis is based on setting tolerable limits for step and touch voltages on metallic elements, which are based on an implicitly probabilistic curve. The working group's approach to this matter goes through the explicit quantification of the risk associated to an earthing system, and its reduction to a residual level.
This methodology maintains or increases the safety on electrical facilities when compared to the currently applied methodology, while being advantageous in economic and technical terms, given that it accounts for greater factor diversity, i. e. the probabilities of simultaneous contact with a metallic element and the occurrence of a fault in the electrical grid.
Two representatives of both companies in the Joint Working Group were in charge of this initiative and hosting this meeting, namely Carlos Cardoso from EDP Labelec/Energy Consulting Area and Miguel Louro from EDP Distribuição/Dispatch and Operation Department.
The first meeting day took place at the riverside Electricity Museum and was concluded with a guided tour for the working group participants around the Museum. The second meeting day was held at EDP Labelec's facilities and ended with a tour around the different company's laboratories, with special focus on the High Voltage Laboratory. This meeting and the tours had a very positive feedback from the working group meeting participants.
The next meeting will take place in Czech Republic next September, and the working group's conclusion is set for 2017.