Does Every Millisecond Really Count - A Comparison of Protection Based Arc Flash Mitigation Techniques

Much attention has been given to mitigation of the arc flash hazard using various fast protection schemes such as light sensing and differential relaying. This paper examines several techniques and quantifies each technic with model systems. The model system consists of several Thevenin equivalent circuits which produces different maximum fault current levels. These Thevenin equivalent circuits are then examined to build a graph of clearing time verses incident energy. Circuits at 2.3KV, 4KV, 13.8KV, and 0.48KV with fault current ranging from 5KA to 30KA are examined. The paper also discusses light sensing, bus differential, zone interlocking, and time current coordination and how each scheme will affect the incident energy of the model system.