Active power in a three-phase power system can generally be evaluated by three wattmeters connected as shown in Figure 3.16.
For each power meter, the current lead is connected on a phase wire and the voltmeter lead is connected between the same wire and an artificial neutral point O, whose position is fixed by the voltmeter impedance of power meters or by suitable external impedances.
Under these conditions, absorbed power will be the sum of the three wattmeter indications: