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Topic Title: transformer size
Topic Summary: question about 100kVA transformer
Created On: 16 February 2013 04:55 AM
Status: Read Only
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 16 February 2013 04:55 AM
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fitzpatrick1976

Posts: 31
Joined: 15 December 2006

Ignoring p.f. for simplicity:

Am I correct in saying that a single phase transformer produces more amps than same sized three phase transformer? for 100kva transformer

single phase power = vi
100000/230 = 434 amps in total

three phase power = root3 v.i
100000/1.73x400 = 144 amps in total?

Is this correct? or am I missing something obvious, like is I actually per phase for three phase?
 16 February 2013 02:45 PM
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sfchew

Posts: 589
Joined: 10 December 2002

Your single and 3 phase currents are correct.

Regards
Chris Chew
 16 February 2013 07:47 PM
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fitzpatrick1976

Posts: 31
Joined: 15 December 2006

three phase power = root3 v.i
100000/1.73x400 = 144 amps in total ????

is the 144 amps for all three phases in total or one phase giving a total of approx 144*3=332 amps in total?
 18 February 2013 12:49 PM
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hpcompaq

Posts: 78
Joined: 27 September 2007

Hello.

144 amps in each of the three phases.
 21 February 2013 01:14 AM
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fitzpatrick1976

Posts: 31
Joined: 15 December 2006

thanks for that.... I am surprised by how many electrical engineers dont know the answer to this one.
IET » Energy » transformer size

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