Apparent Power

[Sharon]

It's amazing the effect intense studying has on your brain. Now I am tripping up on something which I'm sure is very simple - the equation for apparent power.

S=VI* or S=VICos(theta) or S=sqrt(3)VICos(theta)

How do I know when to use which equation?

Thanks....Sharon :tardbang:

 

[Flyer_PE]

Here are the equations:

Apparent Power for a single phase system: S = VI*

Apparent power for a three-phase system: S = (sqrt3)VI*

Real Power (Watts): P = S cos(theta)

Reactive Power (VAR): Q = S sin(theta)

 

[Sharon]

Here are the equations:
Apparent Power for a single phase system: S = VI*

Apparent power for a three-phase system: S = (sqrt3)VI*

Real Power (Watts): P = S cos(theta)

Reactive Power (VAR): Q = S sin(theta)

Thank You!....Sharon