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Code No: R05310204
Set No. 1
III B.Tech I Semester Supplimentary Examinations, February 2008
(Electrical & Electronic Engineering)
Time: 3 hours
Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
(a) Explain the following terms related to armature winding:
i. Double layer
ii. Single Layer
iii. Short pitch
(b) Give the winding calculation for a 3-Φ armature winding with following details:
Pole = 8, Number of slots = 54, Double layer winding.
(a) Explain the effects of harmonics present in generated emf of alternator.
(b) The flux distribution curve of a smooth core 50 Hz generator is B = sin θ +
0.2 sin 3θ + 0.2 sin 5θ + 0.2 sin 7θ wb/m2 where θ is the angle measured from
neutral axis. The pole pitch is 35 cm the core length is 32 cm and stator coil
span is four-fifth pole pitch. Find equation for EMF induced in one turn its
(a) Explain the Roher’s AT method of finding voltage regulation.
(b) A 1 MVA, 6.6 kV, 3-Φ star connected synchronous generator has a synchronous
reactance of 25 Ω per phase. It supplies full load current at 0.8 lagging pf and a
rated terminal voltage. Compute the terminal voltage for the same excitation
when the generator supplies full load current at 0.8 leading pf.
(a) Explain the ‘two bright one dark’ & ‘all dark’ method of synchronization of
(b) The EMFs of two alternators are 3000
6 200 &2900
6 00 V. Their synchronous
impedances are 2 + j20 Ω/ph & 2.5 + j30 Ω/ph. The load impedance is 10 +
j4 Ω/ph. Find the circulating current.
5. A 3-Φ, 6600 V, star connected synchronous motor has effective per phase synchro-