Describing Arc Flash Incident Energy Per Feeder Length in the Presence of Distributed Resources

An approach for arc flash hazard analysis in the presence of distributed resources based on the use of TCC curve equations is proposed in this paper. Determining the available arc flash incident energy and appropriate protective clothing to wear while working on an energized distribution feeder can be a time consuming task. Utilities typically refer to a single, worst-case incident energy per feeder over its entire length to simplify clothing requirements, it is therefore necessary to determine the maximum incident energy present on all feeders that may be worked on energized. The interplay between arcing current and over current protection characteristics makes determining the maximum incident energy and the location of its occurrence a lengthy problem to solve. This is further complicated to a significant degree in the presence of distributed resources. This paper introduces a proposed method that removes the need for an iterative approach in calculating incident energy at several locations on a feeder in a systematic attempt to determine the maximum energy, and introduces the concept of plotting incident energy as a function of system impedance (and so feeder length). This is achieved via an interface to the IEEE 1584 Arc Flash Hazard Calculator correlating discreet impedance increments and available fault current to the time component of TCC curve equations, and plotting the associated arc flash incident energy.