Causes of low Power Factor

Electrical Technology October 8th, 2013Last Modified On: July 9th, 2014 Generation Transmission and Distribution, How To, Over Head Lines, Power factor, Power System, Questions/Answers (Electrical), Single Phase AC Circuits, Three Phase AC Circuits 4 Comments 76,681 Views

 

Causes of low Power Factor

The main cause of low Power factor is Inductive Load. As in pure inductive circuit, Current lags 90° from Voltage, this large difference of phase angle between current and voltage causes zero power factor. Basically, all those circuit having Capacitance and inductance (except resonance circuit (or Tune Circuit) where inductive reactance = capacitive reactance (X_L = Xc), so the circuit becomes a resistive circuit), power factor would be exist over there because Capacitance and inductance causes in difference of phase angle (θ) between current and voltage.

there are a lot of disadvantages of low Pf and we must improve Pf .

Following are the causes of low Power factor:

1. Single phase and three phase induction Motors(Usually, Induction motor works 

    at poor power factor i.e. at:

    Full load, Pf = 0.8 -0.9

    Small load, Pf = 0.2 -0.3

    No Load, Pf may come to Zero (0).

2.  Varying Load in Power System(As we know that load on power system is varying. During low load period, supply voltage is increased which increase the magnetizing current which cause the decreased power factor)

3.  Industrial heating furnaces

4.  Electrical discharge lamps (High intensity discharge lighting) Arc lamps (operate 

     a very low power factor)

5.  Transformers

6.  Harmonic Currents

You may also read about:

• Power Factor
• Active, Reactive, Apparent and Complex Power. Simple explanation with formulas. 
• Disadvantages of Low Power Factor
• Power Factor improvement Methods with Their advantages & Disadvantages
• Advantages of Power factor improvement and Correction  
• How to Calculate the Suitable Capacitor Size in Farads & kVAR for Power factor Improvement (Easiest way ever) 
• How to Convert Capacitor Farads into kVAR and Vice Versa (For Power factor improvement)

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