4.2.2.5 Power Factor Test
The power factor of an insulating liquid is the cosine of the phase angle
between applied sinusoidal voltage and resulting current. The power factor
indicates the dielectric loss of the liquid and thus its dielectric heating. The
power factor test is widely used as an acceptance and preventive maintenance
test for insulating liquid. Liquid power factor testing in the fi eld is
usually done with portable, direct-reading power factor measuring test