Power Factor

This is a factor that describes the relationship between the current and voltage waves that are being supplied.

If these waves are completely synchronised, then power factor is set to 1. This means the maximum power is being transferred.

If these waves are completely asynchronous, then power factor is set to 0. This means no power is being transferred.

There is a further factor, which is if the current wave is leading or lagging the voltage wave.

The normal convention is that current wave for practically all power-system loads i.e. induction circuits, lag the voltage wave. The consequence of this is:

• Positive Reactive Load Power is associated with Power Factor = lag, for example, Induction motor

• Negative Reactive Load Power is associated with Power Factor = lead, for example, Capacitors