Electrical Efficiency
Reactive Power, Power Factor and Compensation Guide
Motors, transformers and other inductive loads draw reactive as well as active power. Reactive flow does not produce useful work but occupies cable and transformer capacity; correct compensation improves power factor and reduces system loading.
What does power factor show?
Power factor is the ratio of active power to apparent power. A low value can mean higher current for the same useful output, increasing losses, voltage drop and equipment loading.
How should capacitor stages be managed?
A compensation relay switches capacitor stages according to load. Incorrect current-transformer direction, stage size, contactor condition or harmonic levels can cause over- or under-compensation, so maintenance decisions should use measured trends.
Evaluate harmonics at the same time
Capacitors can create resonance risk in harmonic-rich networks. Facilities with many non-linear loads should monitor total harmonic distortion, temperature and stage currents alongside power factor, with the design verified by a qualified electrical engineer.
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