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

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

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

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

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)

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