In a flash - Use of instantaneous trip functions with current-limiting fuses to reduce arc flash energy without losing coordination

Abstract

Arc flash hazard studies have forced engineers to rethink many of the irrefutable concepts of coordination. Absolute coordination can limit the amount of the power system deenergized by a fault. But is this achieved at the cost of increased damage to equipment and increased hazards to personnel who happen to be near the point of a fault? It can possibly take far longer to recover from a fault that caused extensive damage and/or injury to personnel than from a slightly uncoordinated loss of power where little damage occurs. Why should available arc energy levels be reduced? The required use of hazard category 3 or 4 personnel protective equipment (PPE) for work in high-arc-energy environments can dramatically drive up the difficulty and cost of work that is simple when normal clothing can be worn. If hazard category 3 or 4 hazards exists, then personnel will be exposed to life-threatening hazards and will depend upon all the required clothing and exact adherence to safe work practices for survival.