125 kVA – Going, going, gone!
After much speculation about the fate of the 125 kVA transformer “exception”, the 2018 Edition of IEEE 1584 – IEEE Guide for Performing Arc-Flash Hazard Calculations has finally been published and made it official. The 125 kVA transformer exception has been deleted!
In its place is the new language:
“Sustainable arcs are possible but are less likely in three-phase systems operating at 240 V nominal or less with an available short circuit current below 2000A”Continue reading →
One sentence in the IEEE 1584 Standard, IEEE Guide for Performing Arc-Flash Hazard Calculations, frequently has people scratching their heads: Equipment below 240V need not be considered unless it involves at least one 125 kVA or larger low-impedance transformer in its immediate power supply. What does this sentence mean? What is so significant about 240 volts and 125 kilovolt-amperes?
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