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 (XL = 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.
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)
6. Harmonic Currents
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