Fire Dynamics Simulation of High Energy Arcing Fault in Medium Voltage Switchgear : Evaluation of Modeling Approach with Radiant Fraction Application

High Energy Arcing Fault (HEAF) is a critical accident type in electrical equipment. Unlike ordinary fires, HEAF can release large of energy in a very short time, producing extremely high temperatures, rapid pressure rises, and strong mechanical shocks. Such phenomena pose severe risks of equipment damage and secondary hazards, and thus cannot be regarded simply as fire events. Instead, they require dedicated engineering approaches and quantitative assessment methods. Accurate understanding of HEAF mechanisms and numerical analysis of the released energy, including its thermal and fluid dynamic characteristics, are essential for accident prevention and for establishing design criteria. Fire Dynamics Simulation (FDS) provides a useful framework for this purpose, as it enables scenario-based modeling that incorporates arc initiation location, released energy, heat release rate, and pressure effects. Through such simulations, it becomes possible to predict fire development patterns and to estimate the Zone of Influence (ZOI) with greater precision. In this study, a numerical HEAF model for medium voltage switchgear was developed, focusing on a generator-fed fault scenario. The impact of HEAF was evaluated by comparing cases with and without the application of the radiant fraction according to arc power. The analysis results indicate that, while slight variations appear depending on the radiant fraction, enclosure damage and ZOI remain largely unchanged. This finding supports the use of maximum arc power with radiant fraction as an efficient analysis method. Overall, the FDS-based HEAF modeling approach provides a useful tool for assessing HEAF risks, supporting equipment design, improving protective measures, and contributing to regulatory development.