Arc Flash and Coordination Study Conflict in an Older Industrial Plant

Abstract

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, 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 "Extreme Danger" 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.

Application of Time-Voltage Characteristics in Overcurrent Scheme to Reduce Arc-Flash Incident Energy for Safety and Reliability of Microgrid Protection

“…Therefore, finding the optimum settings of OCRs that consider the AFIE categories, definite regions, and DGs would provide a significantly more secure environment for workers and equipment. Several studies have used a light sensor (energy sensor) or differential protection to detect the occurrence of AF [36][37][38][39]. The occurrence of AF with circuit breakers inside sub-stations makes it possible to use the existing voltage transformers inside those substations to obtain voltage readings, which can be implemented in the inverse TCC of the overcurrent relay to obtain the least possible time in case of fault, as well as the possibility of adjusting the TCC within the numerical OCRs that are commonly installed and utilized in the existing DNs.…”