Why power factor matters

Inductive loads — motors, transformers, ballasts — draw current out of phase with the voltage. The result is a higher current for the same useful power: larger cable losses, reduced transformer capacity, and often a tariff penalty. Capacitor banks correct this by supplying the reactive current locally.

The controller’s job

It measures the power factor continuously and switches capacitor stages in and out to hold the target. It decides when to switch, which stage to use, and when to stop.

Settings that matter

Target power factor, typically set slightly inductive to avoid over-correction

The switching delay, which must allow for the capacitor discharge time

The stage configuration — equal stages, or a binary arrangement for finer control

The current transformer ratio and position, which the controller reads to make its decision

Whether detuning reactors are needed, which depends on the harmonic environment

Where it goes wrong

Over-correction, which raises the voltage and stresses capacitors.

Switching too fast, which shortens capacitor life.

A CT installed in the wrong place, so the controller corrects the wrong quantity.

No detuning in a harmonic-rich installation, where capacitors can amplify harmonics instead of reducing current.