# 3 phase power systems

#### coley01

Joined Jun 30, 2010
1
I am trying to calculate the power consumption for a 3 phase motor. The load is varying so I am taking the current readings on each of the 3 phases every second. I know the voltage and power factors. I originally thought I would just calculate Pi=I*V*PF*3600 to get Wh for each phase and then just add the three phases and then add all the Pi's for a day to know the power consumption for one day. Then I was looking at 3 phase calculations and it said you have to multiply by the square root of 3. Is this correct? Would I have to multiply Pi by the square root of 3 and then do the summation.

#### Dx3

Joined Jun 19, 2010
87
A quick search for "3 phase power formula" got me, "real power = radical 3 EI cos theta"

#### GetDeviceInfo

Joined Jun 7, 2009
1,866
Power consumption is volts x amps x sqrt2. Power output is reduced by the power factor.

I mean sqrt 3.

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