Power Factor Meter:

A power factor meter is a category of electrodynamometer movement while it is made along with two movable coils set at right angles to each other. A method of connection of this category of power factor meter, in a 3ø circuit, is shown in Figure. The two stationary coils, S and S ¹, are linked in series in Phase B.  A Coils M and M¹ are mounted on a common shaft that is free to move without restraint or control springs.  These coils are connected along with their series resistors from Phase B to Phase A and from Phase B to Phase C. At a power factor of unity, one potential coil current leads and one lags the current in Phase B by 30°; therefore, the coils are balanced in the position shown in Figure.  A change in power factor will cause the current of one potential coil to become more in phase and the other potential coil to be more out of phase within the current in Phase B, so which the moving element and pointer take a new position of balance to display the new power factor.

Figure: ø Power Factor Meter Schematic