Why we want to improve the power factor?

Answer 1

The best way to improve power factor is by adding capacitors. Low power factor is due to reactive loads (motors, pumps, etc.) that are connected to your electrical system.

ADDITION

The best way to improve power factor in the case of motors is to use a motor drive, like a Variable Frequency Drive. These drives allow very precise control over a motor, unlike the very sudden, jerky starting and stopping across the line seen when using a motor starter. They eliminate the huge inrush current required to start motors that causes low PF.

Answer:

1) Power factor can be calculated by connecting an energy meter [P] (voltage coil in parallel & current coil in series with the load), a voltmeter [V] across load and an ammeter [A] in series with the load. Measure P, V & I.

Since, Active Power (P) = V.I.Cosϕ

power factor = Cosϕ = P/VI

2) Power factor is usually (industrially) improved by connecting a shunt (parallel) capacitor bank at feeding end.

How it works??

Inductive loads contain both inductors and resistors. But due to phasor difference of coils and caps when voltage is applied across both, the two currents results in a smaller net current finally. So now the angle (ϕ) between the voltage phasor and current phasor is lessened. When ϕ is reduced, Cosϕ is risen resulting in a higher power factor.

Answer 2

Single phase PF = Input Watts/Volts x Amps. Three phase PF =Input Watts/Volts x Amps x1.732.

Additional Answer

You can determine the power factor of a circuit using three instruments: a voltmeter, and ammeter, and a wattmeter.

Multiplying the voltmeter reading by the ammeter reading will supply the value of the apparent power in volt amperes. The wattmeter reading will supply the value of the true power in watts.

Divide the number of watts by the number of volt amperes, and that will indicate the power factor of the circuit.

Answer 3

AnswerThe purpose of power factor improvement is simply to reduce the load current drawn from the supply. This allows conductors of smaller cross-sectional area to be utilised, reducing the amount (and cost) of copper used in those conductors and other supply plant.

In the case of larger commercial and industrial loads, power factor is part of the tariff, and loads with low power factors may be financially penalised, so higher power factors are desirable as a means of reducing utility bills.

Answer 4

power factor is the ratio of kilo watt & kAV.

PF is the ratio of resistance & Impedance.

PF define as cos fai.

Answer

Power factor is the cosine of the phase angle. So, if a circuit's load current is in phase with the supply voltage (a purely resistive load), then its phase angle is zero, and its power factor is unity (one). For an inductive-resistive load, the load current will lag by some angle, so its power factor will be less than unity. Power factor is also the ratio of a load's true power and its apparent power.

A load with a lagging power factor is drawing more load current than necessary. So, power-factor improvement describes a means of increasing the power factor towards unity, thus reducing the load current. This is usually done by connecting a capacitor of suitable value, expressed in reactive volt amperes, in parallel with the load.

The mathematics involved is too complex to describe in detail in this answer but, briefly, it involves calculating the circuit's existing reactive volt amperes, and subtracting from this the reactive volt amperes necessary to improve the power factor to its desired value. The result is the reactive volt amperes of the required capacitor. Note that power factor improvement capacitors are expressed in reactive volt amperes, and not farads.