![]() The plot below shows the median arc current variation in percent for each of the five electrode configurations. The arc current variation was determined from the median of the measured variation at each voltage level. The value of the arc current variation is no longer fixed to 15% but calculated continuously based on the equations provided in section 4.5 of IEEE 1584-2018. The calculator provides the minimum approach distance, in feet or meters (depending on your selection), for phase-to-ground and phase-to-phase exposures. ![]() Based on the analysis done during the new arc flash model development phase, it was found that the variation in the arc current was higher at voltages below 480 Volts and far less at voltages such as 600 Volts and 2700 Volts ac. The physical concept of arc current variation is not changed, however, it was improved. It includes only the average of all three-phase arc currents. The average current model in 2002 does not include the arc current measured during ignition or extinguishing periods of the arc. Also, the magnitude of the arc current can vary as the arc ignites, persists and extinguishes. The NFPA 70E and CSA Z462 standards provide guidance on the minimum distances that should be maintained between energized electrical equipment and workers based on the incident energy levels. In reality, the arc current can experience variations caused by the ac and dc components of the short-circuit current. The arc flash boundary is the minimum safe distance from the energized equipment that an unqualified worker can approach without wearing PPE. The arc current predicted by the model is considered to be the average arc current for the duration of the arc. This is the reason why the new IEEE 1584-2018 model applied an enhanced arc current model. The arc current is the most important factor to determine the operation time of overcurrent protective devices. Specification for Power System Analysis.Cloud - Collaborative Project Management - NetPM.Intelligent Electrical Single-Line Diagram - iSLD.Microgrid Controller & Energy Management - µGrid. ![]() The arc-flash boundary is typically the outermost of all approach boundaries and must be marked with barricading and hazard signage. ![]() Which approach boundary is the closest to the exposed energized parts.
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