Q. Consider an elementary three-phase, four-pole alternator with a wye-connected armature winding, consisting of full-pitch concentrated coils.  Each phase

coil has three turns, and all the turns in any one phase are connected in series. The flux per pole, distributed sinusoidally in space, is 0.1 Wb. The rotor is driven at 1800 r/min.

(a) Calculate the rms voltage generated in each phase.

(b) If a voltmeter were connected across the two line terminals, what would it read?

(c) For the a-b-c phase sequence, take t = 0at the instant when the flux linkages with the a-phase are maximum.

(i) Express the three phase voltages as functions of time.

(ii) Draw a corresponding phasor diagram of these voltages with the a-phase voltage as reference.

(iii) Represent the line-to-line voltages on the phasor diagram in part (ii).