DETERMINATION OF THE SIZE OF PRESSURE RELIEF OPENINGS IN A COMPACT SUBSTATION DUE TO FAULT ARCS

摘要

This paper addresses pressure calculations due to a fault arc in typical air-insulated medium voltage switchgear in a compact substation in order to determine the size of relief openings in the substation. Two calculation methods are analysed. The first method employs a computational fluid dynamics (CFD) solver and the second one is based on a new refined method providing spatially averaged results (improved standard calculation method, ISC). Fault arc experiments with pressure recordings at different positions inside the substation are used as references. The ISC method provides rather accurate results and proves to be well-suited for such kind of pressure calculations. For an exemplary case a series of experiments and pressure calculations are performed. Maximum overpressure values are determined as function of the size of the relief opening to the environment and of the volume of the substation. Such results are of importance for the design of substations with respect to acceptable maximum overpressure values.