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Code No: V3111/R07
Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
(Electrical & Electronic Engineering)
Time: 3 hours
Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
(a) Explain clearly, the fractional slot winding with all related calculations.
(b) A part of an alternator winding consist of six coils in series, each coil having
an EMF of 10 V RMS induced in it. The coils are placed in successive slots
and between each slot and the next; there is an electrical phase displacement
of 30o. Find the EMF of the six coils in series.
(a) What are harmonics? Explain how harmonics are present in generated e.m.f
of alternator? What are the effects of hormonics an generated emf?
(b) A star connected 3-Φ alternator has an induced EMF of 400 V between the
lines. Due to presence of third harmonic component, the phase voltage is 244
V. Find the value of
i. Find the value of third harmonic voltage.
(a) Explain the ‘Zero power factor’ method of finding voltage regulation of an
(b) The no load excitation of an alternator required to give rated voltage is 1
pu. In a short circuit test with full current flowing in the armature, the field
excitation was 0.75 pu. Determine the approximate excitation that will be
required to give full load current at 0.866 PF lagging at the rated terminal
4. A 4 kVA, 3-Φ, 110 V, 50 Hz, star connected alternator has ×d = 3 Ω & xq = 2 Ω.
The machine is delivering full load current at 0.8 pf lagging at rated voltage. Find
the induced EMF, load angle, maximum power delivered.
(a) A 3-Φ, star connected, 440 V, synchronous motor ta