Equipment voltage ratings

[thinker]

This could be a very simple question, but after many years in electrical engineering I suddenly realized that can not determine voltage classification of the VFD system (enclosure) that has input voltage 575V AC and DC bus voltage 850 V DC. Is such equipment classification considered to be below 600V per NEC or above 600V? Is the rating assignment based on input voltage or actually maximum voltage that exists in the system?

 

[xnuke]

Since the LV cutoff went from 600 V to 1000 V in the 2014 NEC, I'm wondering why you're worrying about this?

By the way, the VFD would be below 600 V per NEC. The voltages inside don't matter. Consider that CRT-based TV sets were 115 V loads, but produced thousands of volts internally to operate the CRT. Regardless of the VFD rating, though, wouldn't you be connecting the VFD to a 600 V system?

xnuke
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