Difference Between Cos (Phi) And Power Factor

haha

http://en.wikipedia.org/wiki/Power_factor

Look up the definition of "power factor." I think you'll find the answer you seek . . .

All kidding aside, cos(Phi) of the angular difference between voltage and current in a circuit is the mathematical expression of what is known as Power Factor.

In North America we tend to use only the word description, elsewhere in the world they use cos(Phi) because that designation remains the same regardless of translation issues from language to language.

Yes, you absolutelly right

I have come to know that if there are harmonics in the supply then Cos(phi) and True Power factor wouldn't the same. Cos(phi) will usually read higher than True Power Factor.

Who told you that? It some times right. For nonsin wave situation, for a simple example, a sine wave current run through ferrite core solenoid, it will be transformed. lots of subhomanic waves were produced, then the PF will be less than the number being in sine wave state condition. PF= a x cos phi, where a <=1. But here, most peple like to disucss it in sine wave situation, so cos fai equal to PF.(a=1)

Duh

Dear Mr.signode,

The answer for your Question is NO DIFFERENCE between cosfi and P.F

DHAYANANDHAN.S

Signode is correct. If you have more than one frequency component on you network (hamonic components) then PF is not equal to cos(phi).

cos(phi) = P1/S1 (P1 power at fundamental frequency and S1 Active power at fundamental frequency)

PF = P/S (P total power on the netowrk, S total active power on the network)

So PF=cos(phi) only if both voltage and current are perfectly sinusoidal.

In most cases this difference is very little and you can asume PF=cos(phi) (Like most text books does)