# Three Phase Pie Formula



## stuiec (Sep 25, 2010)

MIKEFLASH said:


> I was wondering on a three phase 120/208 volt system what voltage would you use to plug into the pie formula?


Depends on what you know, and what you are trying to find.


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## 480sparky (Sep 20, 2007)

8 cups sliced, peeled assorted baking apples - about 3 lbs. (Granny Smith, Cortland, Jonathan)
2 Tablespoons lemon juice
3/4 cup white sugar
1/4 cup brown sugar
1/4 cup all-purpose flour
1 teaspoon ground cinnamon
1/4 teaspoon ground nutmeg
2 Tablespoons butter 
1 egg yolk
1 Tablespoon milk


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## MIKEFLASH (Apr 14, 2012)

stuiec said:


> Depends on what you know, and what you are trying to find.


Well i have the wattage to this data rack but need to know what voltage to insert into the equation to find out how many amps it draws


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## fraserelectrical (Apr 14, 2012)

i' used to a 230/400 volt system, but to convert for power calcs we multiply the single phase voltage to a 3 phase system by root 3 or 1.71 e.g p=VI changes to P= VI times 1.71, to get the single phase from a 3 phase calc we do the reverse of this


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## HARRY304E (Sep 15, 2010)

MIKEFLASH said:


> I was wondering on a three phase 120/208 volt system what voltage would you use to plug into the pie formula?


What are you looking for? 208/1.73=120 ?

Welcome to the forum....:thumbup:


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## 480sparky (Sep 20, 2007)

MIKEFLASH said:


> Well i have the wattage to this data rack but need to know what voltage to insert into the equation to find out how many amps it draws


You don't know the voltage required by the rack?


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## HARRY304E (Sep 15, 2010)

MIKEFLASH said:


> Well i have the wattage to this data rack but need to know what voltage to insert into the equation to find out how many amps it draws


3,120Watts/208Volts= 15 amps. W/E=I


15 Amps x208Volts = 3120 watts. I/E=W


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## MDShunk (Jan 7, 2007)

480sparky said:


> You don't know the voltage required by the rack?


Many of these PDU's get fed with two (or three) hots and a neutral to serve a variety of loads.


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## JohnR (Apr 12, 2010)

Unless you really need it for a specific load, make sure to run separate neutrals to each circuit. You never want to have a dropped neutral on a data rack. Your insurance won't like it.


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## 480sparky (Sep 20, 2007)

MDShunk said:


> Many of these PDU's get fed with two (or three) hots and a neutral to serve a variety of loads.



I know... but why isn't the voltage requirement of the rack already known? Seems to be a cart-before-the-horse question.


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## MIKEFLASH (Apr 14, 2012)

fraserelectrical said:


> i' used to a 230/400 volt system, but to convert for power calcs we multiply the single phase voltage to a 3 phase system by root 3 or 1.71 e.g p=VI changes to P= VI times 1.71, to get the single phase from a 3 phase calc we do the reverse of this


Thanks for the answer


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