Arc Flash Analysis
Arc flash is rapid release of energy in the form of hot plasma, metal vapours of arcing electrodes, ionized gases forming conductive path between phases, neutral or earth through a dielectric medium/air, creating severe thermal effect, intense light, UV emissions, volumetric expansion/blast with creation of toxic gases, shrapnel/splinters and high sound waves, causing most serious effects on persons around and collateral damages to the assets.
It could be difficult to predict direction of arc flash due to magnetic field created by short circuit current and hence, resulting movements of arc plasma. Arc may track path through body from surface of body to earth in case of HV systems.
Arc flash risk assessment shall be carried out from the point of view of possibility of occurrence, potential severity of injury, damage to health and collateral damages to system/assets.
Severity of arc flash hazard depends on incident energy which is proportional to the magnitude of fault current, arc clearing time, and distance from the arc electrode, which further results in irreversible damages to skin/body due to burns of various degrees, damages ears/hearing eyes/optical system and mental trauma.
The arc flash hazard shall be handled at three levels as under
- eliminate chances of occurrence
- mitigate hazard/incident energy
- use of PPE
Reference Standard: IEEE Std 1584, IEEE Std 242, IEEE Std 551, IEEE Std 1584.1, IEEE Std C37.010,
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