What is Power Factor Correction (Compensation)?
Supplying reactive power locally with a capacitor bank to raise the power factor and avoid reactive penalties.
Power factor correction (compensation) is the practice of supplying a facility's reactive power locally with an on-site capacitor bank instead of drawing it from the grid. Inductive loads draw reactive power and lower the power factor (cosφ); compensation supplies that reactive power from capacitors, reducing the reactive power drawn from the grid, bringing the power factor closer to 1 and eliminating the reactive penalty.
A compensation panel consists of stepped capacitor groups controlled by a reactive power relay. As load changes through the day, the relay engages and disengages the appropriate steps. Correct sizing is critical: too little compensation leads to an inductive penalty, while over-compensation causes a capacitive penalty at low load.
Capacitors lose capacity over time and can be damaged in high-harmonic (THD) environments. A compensation system therefore cannot be installed and forgotten; the health of the steps, the power factor and the harmonic level must be monitored continuously.
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