Question

A three-phase, 280 V, 60 Hz, 20 hp, 1710 r/m. Y-connected induction motor has the following impedances in ohms per phase referred to the stator circuit:

R₁=0.12 Ω.                Rˈ2=0.1 Ω

X₁=Xˈ₂=0.25 Ω        X_m=10 Ω

A total rotational loss are 400 W. The core loss is lumped in with the rotational losses. For a slip of 0.05 at the rated voltage and rated frequency. Find:

a) The numbers of poles of the motor.

b) The stator current.

c) the power factor of the motor.

d) The input power of the motor.

e) The developed mechanical power.

f) The efficiency of the motor.

Answer 1