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What is a 'Virtual Main' and how do I use it to reduce Arc Flash Incident Energy?

A virtual Main consists of a digital relay and CT's added to the LV side of a substation transformer and wired to a Fault Breaking overcurrent device (Vacuum C/B) with the ability to use a "Maintenance Switch" to set a lower fault level trip or to use Short time Zone interlocking with the Secondary feeders to allow for faster tripping of the "virtual" main. 
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