cosφ shows how much current does useful work; low values waste capacity.
PF=P/S=cosφ for sinusoids. Lagging (inductive loads) or leading (capacitive). Low PF raises current, I²R losses and voltage drop for the same real power. Utilities penalise PF below ~0.9.
A 10 kW load at PF 0.8 draws 25% more current than at PF 1.
A low power factor draws extra current for the same useful power, which increases losses and can lead to utility penalties.
cosφ shows how much current does useful work; low values waste capacity.
A low power factor draws extra current for the same useful power, which increases losses and can lead to utility penalties.
Values close to one are good. Many utilities penalise factors below about 0.9, so improving it can reduce costs.
The magnitude is between zero and one. The sign indicates whether the current leads or lags the voltage, which depends on the load type.
Typical applications include checking whether a factory's power factor triggers a utility charge, selecting a motor drive to avoid poor power factor and sizing cables for a load with low power factor.
Study "Power in AC circuits" first (topic 42 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Motors have 0.7–0.9 PF. Non-linear loads have distortion PF. Unity is ideal.
A 10 kW load at PF 0.8 draws 25% more current than at PF 1.
The next topic is "Power factor correction", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 43 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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