Aim:- Measurement of the 3phase power by the two watt meter method.
Ammeter (0-5A)- 1no.
Voltmeter (0-600v) –1no
Here two wattmeter are connected to measure power in 3 phase circuit. Let V1,V2,V3
be rms values of phase voltage and i1,i2,i3 be rms values of line current
Power factor=cos f
Reading of P1 wattmeter =V1Ö3i1cos(30-f)
Reading of P2 wattmeter= V2Ö3i2cos(30+f)
Sum of two wattmeter readings=P=P1+P2
= Ö3Vphiph[cos( 30-f)+cos(30+f)]
Sr no Voltage Current Power 3 phase watt
1) Make the arrangement as per the circuit diagram.
2) Adjust supply voltage to 100v take the reading when the wattmeter is connected
between the R and Y phase.
3) Repeat previous for the different reading of the voltage.
4) Also note the corresponding current.
5) Now connect wattmeter between R and B phase .
6) Repeat the previous procedure which will give by the total power consumed by
Result:- Hence it is found that the calculated power and the measured power by the two
1)What do you mean by the 3phase wattmeter?
2)Explain the short how the wattmeter is connected in the circuit to measure
the power delivered to the Load?