Consider a 2-pole, 50 Hz, cylindrical rotor ac machine. The air-gap radius is 0.1 m, the air-gap distance is 0.002 m and the air-gap axial length is 0.3 m. The rotor has 12 slots with a 2-pole, single-layer, full-pitched, distributed winding. Each slot has a coil side having 10 conductors (turns). The stator has 18 slots with a 2 pole, double-layer, fractionally pitched, distributed, 3-phase ac winding. Each slot has 2 coil sides and each coil side has 15 conductors (turns).

a. Draw the rotor winding diagram and calculate the rotor winding factor.

b. When the rotor winding is excited by a dc current of 10 A while the rotor is rotating at a speed of 3000 rpm, the measured fundamental voltage between the terminals of one stator phase is 175 V-rms. Find the possible chording (pitch) factors of the stator winding in terms of the nearest slot number. Draw the stator winding diagrams for these cases.

c. The stator winding is excited by a 3-phase, 50 Hz, 5 A (peak), balanced ac current system without rotor excitation. Calculate the air-gap fundamental flux per-pole and the generated fundamental voltage between the terminals of the rotor winding when the rotor is stationary.