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Old 11-07-2018, 11:51 PM   #1
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Question 3 Phase Generator Output

Could someone please confirm my understanding of 3 phase generators power output. I'm in Australia so all calculations are in 240v



A 30kVA generator in total can provide a theoretical maximum of 30,000/240 = 125A which would be 41.6A per phase? Using a power factor or 0.8 we get a total of 125*0.8 = 100A or 33.3A per phase.


So a 30kva generator is capable of running 3x32 amp distribution boxes?



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Old 11-07-2018, 11:57 PM   #2
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In the real world, the alternator is loaded by real loads.

Distribution boxes are NOT real loads. They are distribution nodes.

You have to ask yourself: "What are the actual net loads to be served?"

This calculation is termed a load-calc... what else?

Set-up a spread sheet program and punch in the numbers.

You'll want to look at actual Watts as well as keep an eye on Power Factor.

( If poor, the latter doesn't load up the alternator, but does figure in conductor sizing. )

Last edited by telsa; 11-08-2018 at 12:10 AM.
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Old 11-08-2018, 12:20 AM   #3
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Thanks

So assuming unrealistic ideal loads I'm correct? Just after a sanity check that I'm not out by a factor of 3.
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Old 11-08-2018, 08:29 AM   #4
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Quote:
Originally Posted by Beauc View Post
[COLOR=#212121][FONT=sans-serif]A 30kVA generator in total can provide a theoretical maximum of 30,000/240 = 125A which would be 41.6A per phase?
Huh?
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Old 11-08-2018, 01:43 PM   #5
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Quote:
Originally Posted by Beauc View Post
A 30kVA generator in total can provide a theoretical maximum of 30,000/240 = 125A which would be 41.6A per phase? Using a power factor or 0.8 we get a total of 125*0.8 = 100A or 33.3A per phase.
So a 30kva generator is capable of running 3x32 amp distribution boxes?

Quote:
Originally Posted by Beauc View Post
Could someone please confirm my understanding of 3 phase generators power output.
I can confirm it is not correct. Are you an electrician? I don't see anything in your profile.

EDIT: I just realized I may be misreading this. Is the 240V L-L or L-N?

Last edited by AK_sparky; 11-08-2018 at 01:47 PM.
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Old 11-08-2018, 03:36 PM   #6
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240v x 1.73 x 33.3a= @13KW
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Old 11-08-2018, 08:29 PM   #7
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30X1000/240x1.732= 72.23 amps

30X.8/x1000/240X1.723= 57.78 amps

or somewhere close to that
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Last edited by brian john; 11-08-2018 at 08:32 PM.
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