![]() It is assumed that a second-degree burn occurs when the incident energy received by the skin equals 5 J/cm2 (1.2 cal/cm2). The plot below shows the median arc current variation in percent for each of the five electrode configurations. An arc flash boundary is the term used to describe the distance at which a person without personal protective equipment (PPE) may get a second-degree burn if an arc flash occurs. 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. 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. In reality, the arc current can experience variations caused by the ac and dc components of the short-circuit current. 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.Arc Flash Boundary in the standard is 1704mm, whilst in the spreadsheet is 1712.51mm. Incident Energy in the standard is 13.343 J/cm2, whilst in the spreadsheet is 13.44 J/cm2. Intelligent Electrical Single-Line Diagram - iSLD Unfortunately, this results in calculated Incident Energy and Arc Flash Boundary values which are higher than those given on pages 67 and 68.Microgrid Controller & Energy Management - µGrid.Electrical SCADA & Control System - eSCADA.Relay Protection & Asset Management - eProtect.Digital Substation & Automation System - SAS.Advanced Distribution Management System - ADMS.Automated Protection & Coordination - Star.
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