studyBecause most methods currently available for analyzing the arc flash incident thermal energy were developed for low and medium-voltage industrial and commercial settings -- and not applicable to practical transmission and substations situations – a study by the Electric Power Research Institute (EPRI) aimed to:

  1. Obtain test results to quantify incident thermal energy from single-arc events that could occur on overhead transmission lines and in outdoor substations,
  2. Develop a simple method for computation of the incident thermal energy in these situations.

“Arc flashes are a serious hazard that may potentially put people in life-threatening situations and cause great damage to existing assets,” according to the introduction of Arc Flash Issues in Transmission and Substation Environments: Modeling of Incident Thermal Energy of Long Arcs. “National Electrical Safety Code (NESC) and the Occupational Safety and Health Administration (OSHA) safety rules have introduced requirements for electric utilities to perform arc flash hazard analysis of all electric facilities operating at and above 1000 volts.

“The 2011 EPRI report 1022632 showed that these methods are not applicable to practical transmission and substations situations and lead to inaccurate estimates of incident thermal energy. This report builds on these results and also proposes needed future research and tests on an actual full-size transmission structure and on actual full-size substation equipment. Arcs in long gaps in open air, especially in the case of transmission structures and in substations where insulators most often occupy the gap, must be modeled with full recognition that the entire arc consists of regions that must be modeled individually, that the arcs in long gaps meander and are thus longer than the gap length, and that various regions of the arc contribute differently to the total incident thermal energy that could impinge on the worker. In the case of transmission lines, the fault current consists of two components, one from each end of the line. In the case of substations, fault current may consist of components from many sources. Methods to deal with such situations need to be developed.”

Click here to download the pdf from the EPRI.

About the EPRI

The Electric Power Research Institute, Inc. conducts research, development and demonstration (RD&D) relating to the generation, delivery and use of electricity for the benefit of the public. An independent, nonprofit organization, EPRI bring together scientists and engineers as well as experts from academia and the industry to help address challenges in electricity. - See more at: