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I'm a physicist by training, so I think I understand voltage, current, phase and power. However, I lack the knowledge to translate between this and the published ratings on three-phase electrical equipment.

If a three-phase UPS is rated at 160 kVA, does this mean that each phase can deliver 160/3 = 53.3 kVA? Or is there a factor of \$\sqrt{3}\$ involved?

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Yes, a 3 phase 160kVA supply would mean 3 single phases each at 53.3kVA.

The factor of \$\sqrt{3}\$ arises in the power calculations when using a line-line voltage.

Note that the UPS may or may not be able to support unbalanced loads.

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  • \$\begingroup\$ The unbalanced load support I would assume is where it gets messy. \$\endgroup\$ – Kortuk May 10 '12 at 16:30

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