Demonstrate that two wattmeters are sufficient to measure power in a three phase balanced star connected circuit with the help of neat circuit diagram and phasor diagram.

3 a]Demonstrate that two wattmeters are sufficient to measure power in a three phase balanced star connected circuit with the help of neat circuit diagram and phasor diagram.

The W1 is connected between phase R and B
The W2 is connected between phase Y and B

W_{1}=V_{RB}I_{R}\cos(V_{RB\angle}I_{R}) and

the angle between V_RB & I_R is 30-\oint_{}^{}

the angle between V_YB & I_Y is 30+\oint_{}^{}