xfmr question?

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rattus said:
Smart, it is pointless to compute these results beyond 3 significant figures.
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I do not disagree :smile:. I just like to keep the potential for accumulative errors at a minimum... a practice which goes way back for me, and old habits are hard to break.
 
Smart $ said:
I do not disagree :smile:. I just like to keep the potential for accumulative errors at a minimum... a practice which goes way back for me, and old habits are hard to break.
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Smart, IMO, that old habit is a good habit (not that my opinion counts, LOL)
 
Smart $ said:
I do not disagree :smile:. I just like to keep the potential for accumulative errors at a minimum... a practice which goes way back for me, and old habits are hard to break.
Click to expand...

Doesn't hurt to use the maximum precision in your calculations since your calculator and computer do it anyway. However, one should round off the results to three figures or whatever is appropriate.
 
rattus said:
Doesn't hurt to use the maximum precision in your calculations since your calculator and computer do it anyway. However, one should round off the results to three figures or whatever is appropriate.
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Right again. I displayed extra decimal places only for demonstration of the inaccuracies. I apologize for not explicitly noting such.
 
question followup celtic, roger?

question followup celtic, roger?

my 30 kva xfmr can be loaded to 83 amps max per tap at 120vac, so i could feed 3 , 208/120 panels with 83 amps each, . is this correct?

so what would the typical connection to the xfmr look like, divided among 3
100 amp panels?
 
don_resqcapt19 said:
Steve,

No...you can feed one 3 phase 208/120 wye panel with 83 amps.
Don
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Why?

Couldn't he feed as many panels as needed (x # of panels x42 ckts) as long as the calculated load did not exceed the OCPD on the secondary?
 
Celtic,
Couldn't he feed as many panels as needed (x # of panels x42 ckts) as long as the calculated load did not exceed the OCPD on the secondary?
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Steve said feed the panel(s) with 83 amps...I am assuming that he wants to use 83 amps at each panel. Sure you can feed as many as you want as long as the total load is less than the transformer rating and as long as the transformer secondary and secondary conductors are protected as required by 450.3 and 240.21(C) respectively.
Don
 
don_resqcapt19 said:
Celtic,

Steve said feed the panel(s) with 83 amps...I am assuming that he wants to use 83 amps at each panel.
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Gotcha...
I see it now:
steveng said:
....so i could feed 3 , 208/120 panels with 83 amps each...
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Thank you Don.
 
don, does that mean i can load each phase of the panel to 83 amps?



i have a 3 phase xfmr, so, i can tap it how many times?


i understand that every time you tap the secondary winding on the xfmr, you must provide an ocpd, fuses, for every panel or switch you feed?

can you give me a specific example of a 30 kva feeding 3 panels , can i parallel tap the secondary, and feed 3 different panels?
 
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