3-Phase Variac Question

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Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com> 

Just a quick question regarding 3-phase variac nameplate ratings.

I have a Superior Electric Powerstat 3-Phase variac which is rated at
240 input (0-280VAC output)

Does this imply that each section of the 3-Phase variac is rated for
240VAC input???  Or does it imply its wired
in such a way that it might accept 208VAC 3-Phase input or similar where
there may only be 120VAC on each section (phase-to-phase)?

Thanks

Dan