4. A 380-V, 60 Hz, 150-hp 0.8-PF-lagging six-pole Y-connected synchronous motor has a synchronous reactance of 1.1 2 and
Posted: Thu Jun 02, 2022 9:16 am
4. A 380-V, 60 Hz, 150-hp 0.8-PF-lagging six-pole Y-connected synchronous motor has a synchronous reactance of 1.1 2 and negligible armature resistance. Ignore its friction, windage, and core losses. (a) If this motor is initially supplying 150-hp at 0.8 PF lagging, what are the magnitudes and angles of excitation voltage and stator current? Draw the phasor diagram for this condition. (9%) (b) Determine the maximum torque that the motor can deliver. (6%) (c) If the field excitation current is now increased by 15% (without changing the prime mover power), find the stator current, and power factor. (6%)