1. Phase a of a 3-phase stator at the instant of carrying maximum current has 60 amperesconductors in the phase belt. Sketch the mmf wave of the phase when the slots/pole/phase are 1, 2, 3, 4 and 5 respectively. Comment upon the change in shape of mmf wave with the number of slots/pole/phase.
2. A 2-pole, 3-phase ac winding is housed in 18 slots, each slot having 12 conductors. Consider the time instant at which the current in phase a has its maximum value of 10 A.
(a) Sketch all the 18 slots on a horizontal axis. Mark the direction of currents in the conductors occupying the slots relevant to phase a. Make a proportional sketch of the mmf wave of phase a only.
(b) Mark the maximum value of the mmf wave on the sketch.
(c) Calculate the peak value of the fundamental of the mmf wave.