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Ups Backed Inverter

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#1 Crusoe


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Posted 17 September 2008 - 11:26 AM

This is my first post.

I need to re-start a three phase Variable speed motor for a brief period (1 min) after a power failure.

I intend using a 220Volt single phase UPS to supply a 220Volt single phase inverter to control a 3.0kW 3 phase motor connected in 220Volt Delta. NB a 3 phase UPS is too expensive

Typically a UPS has an out power factor of 0.7. How do I calculate the size of the UPS? - for a 3kW load, would I need a UPS which was 3000/0.7 = 4285VA (nearest unit 5kVA)?

How do I calculate the line current of a single phase inverter?
What implications/ pitfalls does this have in my application?

Any comments or advise would be greatly appreciated

Thanks in advance

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