Homework Help: Quick question on 3 phase before my final

1. Apr 27, 2008

tanky322

Quick question on 3 phase before my final!!

1. The problem statement, all variables and given/known data

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.

2. Relevant equations
P=(VrmsIrms)cos($$\theta$$)
Q=(VrmsIrms)sin($$\theta$$)

Any help?

2. Apr 29, 2008

PhanthomJay

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.