Power Factor

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Power factor is the Ratio of Active power(P) to Apparent power(S).

Mathematically,

Cos(phi) = P / S

But, S = P + jQ

Where, P = Active power =VI Cos(phi)

And Q = Reactive power= VI sin(phi)


 or, Cos(phi) = VICos(Phi) / VI

 Power factor = Cos(phi)

Simply,we can define; Power factor means the utilisation of useful power from total power.


Best way to understand power factor:

In Series connection,

Let's take phasor diagram of RL series circuit,


From above phasor diagram;we can define,

Power factor describes the direction of resultant current with respect to resultant voltage.
 
--In case of Leading power factor, Resultant current will lead from resultant Voltage.

--In case of lagging power factor, Resultant current will lag from Resultant Voltage.

Cos(phi) = VR / V = I.R / V  = (I/V) * R

Cos(phi) = {(Resultant current / Resultant Voltage)}* R

Cos(phi) = VR / V = I*R / I*Z = R/Z

  

In parallel connection,

Let's take phasor diagram of RL parallel circuit,


From above phasor diagram; we can define,

 power factor describes the direction of resultant voltage with respect to resultant current.

--In case of Leading power factor, Resultant Voltage will lead from Resultant current.

--In case of lagging power factor, Resultant Voltage will lag from Resultant current.


Cos(phi) = Ir / I = (V/R) / (V/Z) = Z /R

Cos(phi) = 1 / RY



Comments

  1. Technical Gyan2 April 2021 at 20:17

    Very easy way to understand power factor.. Thanks for share

    ReplyDelete

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