Hybrid arc flash protection within electrically classified areas

Electrical equipment installed within electrically classified areas; Class I, Division 1 (Zone 1), or Division 2 (Zone 2) locations, require techniques to mitigate flame propagation. Class I, Division 1 and 2, or explosion-proof (NEMA 7) techniques are the most commonly used for this purpose. Other techniques, like, enclosed break, flame proof and restricted breathing, are common available methods. A previous PCIC paper [1], explored the electrical arc flash mitigation of the NEMA 7 design. It was found that this design mitigated the electrical arc flash energies, and helped protect personnel from electrical hazard. This paper will explore, reduction in electrical arc flash energies using simpler, lighter weight, explosion protected design. Results using analytical approach, Computational Fluid Dynamics (CFD) analysis, and proto typing shows enhanced personnel protection.