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Topic Title: How to derive three phase current for an isolation transformer
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Created On: 22 March 2013 07:31 PM
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 22 March 2013 07:31 PM
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Posts: 87
Joined: 25 January 2011


I wonder if any one can cast a light on which method should be used when calculating the required kva for a transformer.

There are two school of thoughts:

1 - Use the highest phase current to determine the kVA

2 - Use the Average current of the three phases to deduce the kVA

With the ever increasing cost of copper and decreasing amount of money being spent on asset option two is appealing, but does it meet regulatory requirements??? - Please help
 22 March 2013 10:50 PM
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Posts: 7052
Joined: 27 December 2005

For a three phase transformer, use the highest phase current to calculate kVA for the most heavily loaded winding, then multiply this value by three. Finally, choose the next kVA size higher (as I doubt you are getting a device specially wound).



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