Power Factor Meter
The power factor meter gives the power factor (p.f) angles which is nothing but the phase angles between the voltage and the current vectors and its scale is calibrated directly in terms of cosΦ. The construction of p.f meter is of different types of which dynamo-meter type is most used for electrical lab work. Dynamo-meter type p.f meter consists of fixed coil called as current coil (CC), moving coil called as pressure coil (PC) which moves in the field produced by the current coil carrying load current.
The power factor meter is tested by using “phantom loading” in order to reduce the power loss. In this method the current coil will carry the load current and it is supplied by a low voltage supply. Rated voltage is applied to the pressure coil (PC), through a phase shifting transformer. The purpose of this arrangement is to phase shift the phase angle between the PC voltage and the current in the current coil.
Here is the formula for finding ‘% error’ at Unity Power Factor (UPF)
