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Equipment voltage ratings

thread242-410807

Equipment voltage ratings

Equipment voltage ratings

(OP)
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?

RE: Equipment voltage ratings

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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