Dear madam, can u pls explain the concept of power factor? what are its uses(if any)and why do power companies charge more if it exceeds a particular limit?

Asked by ARATHI M | 6th Dec, 2013, 10:44: PM

Expert Answer:

For a DC circuit the power is P=VI, and this relationship also holds for the instantaneous power in an AC circuit. However, the average power in an AC circuit expressed in terms of the rms voltage and current is

where is the phase angle between the voltage and current. The additional term is called the power factor

From the phasor diagram for AC impedance, it can be seen that the power factor is


For a purely resistive AC circuit, R=Z and the power factor = 1.


 To maximize the rate at which energy is supplied to a resistive load , we should keep the power factor close to unity.

"unity power factor" is the goal of any electric utility company since if the power factor is less than one, they have to supply more current to the user for a given amount of power use.

An industrial facility will be charged a penalty if its power factor is much different from 1.
If the circuit is highly inductive, it can be made less by putting more capasitance in the circuit, connected in series.
Please ask seperate question as a seperate query.




Answered by Komal Parmar | 9th Dec, 2013, 07:33: PM

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