Arc Flash and Coordination Study Conflict in an Older Industrial Plant

Once arc flash hazard analysis became a requirement for many industrial power system studies, the reduction of arc flash hazards has become an important concern. Inevitably, the factors that lead to reductions in arc flash hazards do not always lead to an improvement in other areas, i.e., in particular, protective device coordination. This paper will examine several particular cases where an arc flash hazard analysis of an older industrial plant yielded several cases of buses where the hazard level was ldquoextreme dangerrdquo above category 4. By changing protective device settings and, if necessary, the devices themselves, the hazard level can be reduced. Methods to maintain coordination, if possible, are discussed.