1. Power Factor Correction
AC POWER CALCULATION
Power Factor Correction
SEE 1023 Circuit Theory

2. Power Factor Correction
Load + V  I
V = Vv
I = Ii
As we have seen before (for sinusoidal voltage and current),
pf = cos (vi)
P = V I cos (vi)
The REAL power (or average power) is transformed into useful energy
e.g. heat, mechanical, light, sound, etc
For a given V and P, loads with high power factor draw LESS current compared with loads with low power factor

3. Power Factor Correction
pf = cos 1 V I1 P
pf = cos 2 V I2
cos 1 > cos 2 Q2
1 < 2 Q1 1 2
Pave
Pave
For a given V and P, loads with high power factor draw LESS current compared with loads with low power factor

4. Power Factor Correction
For a given V and P, loads with high power factor draw LESS current compared with loads with low power factor
Less current results in LESS losses during transmission
I2R
Load
Source + 
Utility company (TNB) charge more to loads with LOW power factor
Therefore, it is desirable to increase the power factor

5. Power Factor Correction
How to increase the power factor without altering the voltage or current of the original load? + VL  IL
Vs (rms) QL QC 1 QT 2 PL
Before C added, S = PL + jQL
pf = cos 1
After C added, S = PL + j(QL – QC)
pf = cos 2 i.e. increased
(voltage and current of the original load are retained)

6. Power Factor Correction
How do we calculate C? PL 1 QL QC 2 QT
Voltage across C = Vs (rms)
Impedance of C =