Power Flow in Synchronous Motor

Power Flow in Synchronous Motor

The figure below gives the details regarding the power flow in synchronous motor.

Where

 Power input to a synchronous motor is given by P = 3V_phI_phcosΦ = √3V_LI_LcosΦ. In stator as per the diagram there will be core loss and copper losses taking place. The remaining power will be converted to gross mechanical power.

Hence P_m= Power input to the motor – Total losses in stator.

From the phasor diagram we can write Power input /phase P_i = V_phI_phcosΦ  

Mechanical power developed by the motor P_m= E_bI_a cos ∟ E_b & I_a= E_bI_a cos(δ – Φ)

Assuming iron losses as negligible stator cu losses = P_i - P_m

Power output /phase = P_m – (field cu loss + friction & windage loss +stray loss)