Calculate arc flash energies

 

The evolution of methods used to accurately quantify energy from an electrical arc flash show that each has improved on the findings of its predecessor. The question remains as to whether an arc flash calculation should be performed, even with the knowledge that there are limitations in the only published standard.

 

Methods used to calculate arc flash energies have been implemented over the years:

 

  • The Lee Model: Ralph Lee (1982) used simple theoretical models and basic electrical understanding to express a distance from which a person could walk away with curable burns.
  • The Doughty Neal Model (2000): Tests on a 600 V system aimed to provide a measure of energy incident upon the worker, rather than merely providing safe working distances.
  • IEEE 1584A (2002): The previous research led to limited practical testing by the IEEE with the first guideline published in 2002.
  • Sweeting and Stokes: These experiments raised questions about the guideline.

 

Take note

  • Arc flash burns pose a real threat to personnel working in substations and certain other areas in a plant.
  • Arc flash models exist that allow calculation of the distance from the arc at which the employees are safe.
  • The danger of electrical arc emphasises the need for specialised input and the fact that companies with substations must be sure that staff working in these areas are adequately protected.

 

Published as: Electrical arc flash calculations, By Z Jooma, e-Hazard.com

Electricity+Control, June 2011 (pgs 36 – 38)

Email: zarheer@e-hazard.com