Power Factor in Switched Circuits
In general, for a circuit where the output is switched on and off, how can we analyze the power factor?

In general, the power factor in such a circuit is not the power factor defined as the cosine of the angle between the current and voltage but as the real power divided by the apparent power. In this case, the apparent power is the total RMS voltage including harmonics multiplied by the total RMS current including harmonics. Real power is calculated by multiplying the corresponding instantaneous values of voltage and current and integrating over a cycle. The power factor in this case is the &quot;total power factor&quot; rather than the &quot;displacement power factor.&quot; Some people consider the &quot;total power factor&quot; to be the &quot;true power factor,&quot; but that can lead to calculation errors and nasty surprises.