Power Factor Correction - power factor correction methods - Electrical input

Wednesday, August 15, 2018

Power Factor Correction - power factor correction methods

                                        Power Factor Correction

Power Factor Correction :- it is a kind of techniques  to improve the power factor of a power supply. Power factor correction initiate the power factor of an AC power circuit closer to ONE by supplying or absorbing reactive power, by adding  inductor and capacitor to cancel the capacitive and inductive effect of the load, commonly . Different types of method used to improve power factor are given below---

             Power factor correction methods :-

1.       Using capacitor bank
2.       Using  Synchronous condenser 

 1. Using capacitor bank :- Power factor is improved by connecting capacitor in star connection as well as delta connection in three phase system. Star and delta connection shown in the below :--

Let, Vp = phase voltage
VL = Line voltage
CΔ = capacitor per phase when the capacitors are connected in delta
Qc = Var rating of each phase

Delta Connection :- Vp = VL
CΔ = Qc/ ωVP2 = Qc/ω VL2 …………………………….. (i)
VP = 1/3VL
Capacitance per phase is expressed by equation :-
CY = Qc/ ωVP2 = Qc/ ω (VL/ √3)2 ……………………………. (ii)
             From (i) and (ii)
                             CY = 3CΔ …………………………….(iii)
Equation (iii) define for three phase transformer that the capacitance need in star connection  = three times the capacitance need per phase when capacitors connected in delta and the working voltage of the star connected bank is 1/√3 equal to the delta connection.

These are the reason why capacitors are connected in the delta in three phase system for power factor improvement.

2 . Using  Synchronous condenser :- Power factor also improved by special designed motor known as synchronous condenser. synchronous condenser are connected in parallel with load and was running without mechanical load. Synchronous generator absorbs and generates the reactive power (Var)  by varying the excitation of the motor field winding. Synchronous condenser  are costly and its maintenance and operation are not also easy.


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