Estimation of Burn-Through Probability in SF6 Insulated Substations

Enclosure burn-through in SF6 insulated substations is a rarely occurring event; however, in view of the possibly damaging effects to equipment and personnel, its probability of occurrence warrants a closer examination. This paper presents a model for estimating the likelihood of enclosure burn-through or pressure relief disc bursting during an in-service fault in SF6 substations. Results of a simulation show a 25% burn-through probability per fault in substations with the most probable fault currents in the 50 kA range. The probability of personnel being exposed to the hazardous arcing by-products is discussed.