1.
Obtain expression for output equation of a rotating
machine. Apply this for a synchronous, induction and dc machine.

2.
Discuss factors affecting size of rotating machine and
how the separation of main dimensions is done.

3.
Explain SCR in synchronous machines.

4.
Find the main dimensions of a 20 MVA, 11kV, 50Hz,
150r.p.m., 3-phase water wheel generator. The average gap density is 0.6 Wb /m²
and ampere conductors per meter are 35,000. The peripheral speed should not
exceed 65 m/s at normal running speed in order to limit the run-away speed.

5.
Give procedure for designing the field system of a
three-phase turbo generator from the given design data. Also indicate how much
excitation power may be required for such a generator of about 100 MW capacity.

6.
A 1500 kVA, 3-phase, star-connected, 3300 V, 250 rpm
water wheel generator has the following design data:

Effective
gap length = 7mm

Effective
gap area/pole =
0.075 m²

Winding
factor =
0.955

Field
mmf per pole under rated condition = 7850 A

No.
of field turns/pole = 180

The peak value
of fundamental flux density distribution B…= 0.94 T and peak value of the
actual flux density distribution B…=0.9T.

The
permissible value of current density in field winding is 3 A/mm². Determine:

(i)
Turns / phase

(ii)
MMF for air gap

(iii) Armature
MMF /pole

(iv) Field
current

(v)
Sectional area of field conductor.

7.
Design the suitable values of diameter and length of a
75 MVA, 11 KV, 50 Hz, 3000 rpm, 3-phase star connected alternator. Also
determine the value of flux, conductor per slot, no of turns per phase, and
size of armature conductor. Given

Average gap density = 0.6 T

Amp conductor per m = 50,000

Peripheral speed = 180 m/s

Current density = 6 A/m

^{2}
8.
Calculate the diameter, core length, number of
conductors of the stator, size of conductor, number of stator slots of a 30
MVA, 11KV, 3000 r.p.m. 50Hz star connected turbo alternator. Assume suitable
data:

Bav =0.55
Wb/m², ac =55000 A/m, Kw = 0.955,

Peripheral
velocity = 160 m/s.

9.
If two synchronous machines running at the same speed
and having the same number of poles, the physical dimensions are in the ratio 3
: 2. Compare the outputs, armature copper losses and iron losses in the two
machines. Assume specific magnetic loading and current density to be same for
both the machines.

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