# Quick question on 3 phase before my final

Quick question on 3 phase before my final!!

## Homework Statement

In equations for 3 phase power there is an angle that is mentioned, but I dont know if this is the angle of the impedance or another angle. Im a little confused. The equations are below.

## Homework Equations

P=(VrmsIrms)cos($$\theta$$)
Q=(VrmsIrms)sin($$\theta$$)

Any help?

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PhanthomJay
Homework Helper
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## Homework Statement

In equations for 3 phase power there is an angle that is mentioned, but I dont know if this is the angle of the impedance or another angle. Im a little confused. The equations are below.

## Homework Equations

P=(VrmsIrms)cos($$\theta$$)
Q=(VrmsIrms)sin($$\theta$$)

Any help?
I'm certainly not an electrical expert, but the angle you are referring to is the phase angle betwen the voltage and the current, where $$cos\theta = power factor$$. For purely resistive loads, theta is 0, hence the power factor is unity, and there is no reactive power Q. However, I don't quite understand your equation, since typically ,for power transmsission, $$P= \sqrt3(V)(I)cos\theta$$. That's about it for my electrical knowledge.