Answer:
If no pf value is shown on the loads nameplate:
Use a power analyzer multi-meter like a Fluke brand specialty meter
Also and oscilloscope can be used with dual input. Sinusoidal wave form from voltage input probe and current probe make a dual trace.
There are also power factor transducers that use CT/current xformer and PT potential xformer. Provide an output in a range like
4 m.a. = .5 pf
12 m.a.= unity/1
20 m.a.= -.5 pf
Explanation:
PF = cos(φ)
Where PF is power factor, Φ is phase angle.
