Electrical Troubleshooting
Industrial Electricity and Electronics
50 Hertz Industrial Electricity

What are the methods to calculate and improve power factor?

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2011-03-16 17:54:54
2011-03-16 17:54:54

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.


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.


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.

Related Questions

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using highly inductive loads may lead to reduction in the power factor. or consumption of unappreciable amount of power also results in the same. methods to improve PF . using synchronous condensers using capacitor banks using ow inductive loads

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The 0.8 Power Factor provided by generator manufacturers is not the load power factor, but it is the nominal power factor used to calculate the kW output of an engine to supply the power for a particular alternator kVA output. Alternators are therefore designed to supply their rated kVA at 0.8 lagging power factor.

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A capacitor is connected across the line voltage to improve the power factor.

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Improving power factor does nothing to improve a circuit. It merely affects the amount of current drawn by the load.

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No. They can improve power factor with capacitors, but they can not raise it to unity.

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