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Which of the following is NOT responsible for poor power factor?
1. Variations in power loading
2. Capacitors in the distribution system
3. High voltage
4. Harmonic currents

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Correct Answer - Option 2 : Capacitors in the distribution system

Power factor:

  • The ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents the power that does no useful work.
  • The main cause of the 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 exist over there because Capacitance and inductance cause in difference of phase angle (θ) between current and voltage.
    there are a lot of disadvantages of low Pf and we must improve Pf.

 

Improving Power Factor with Capacitors:

  • The reactive component (KVAR) of any electrical distribution system can easily be reduced in order to improve power factor by using capacitors.
  • Capacitors are basically reactive loads. They tend to generate reactive power hence they find good use in power factor correction application.
  • So instead of having the utility company supply the reactive power that you will end up paying for, get a capacitor bank and have them supply the reactive energy to the system.

 

Variation in the Power System Loading

  • The load demand in the modern power system is not constant throughout the day.
  • The demand is high during the morning and evening hours and the light during the rest of the day.
  • When the system is loaded lightly, the voltage increases, increasing the magnetization current demand of the machine. This causes a poor power factor in the system.

 

Harmonic Current: The presence of harmonic current reduces the power factor in the system.

Due to high voltage also reduce power factor of the systems

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