Download AKTU B-Tech 3rd Sem 2016-2017 NEE 301 Electro Mechanical Energy Conversion I Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 3rd Semester (Third Semester) 2016-2017 NEE 301 Electro Mechanical Energy Conversion I Question Paper

Printed Pages: 4 NEE-301
? (Following Paper ID and Roll No. to be ?lled in your
Answer Books)
Paper ll) : 2012374 Roll No.
B.TECH.
Regular Theory Examination (Odd Sem 5111), 2016-17
EMEC - I ? '
Time : 3 Hours Max. Marks : 100
SECTION -A
1. Attempt all parts of the followings : ' (10X2=20)
a)
b)
c),
d)
e)
f)
g)
h)
Write the energy balance equation for motor action
and draw power ?ow diagram.
What is back-emf in a dc motar?
Define ?reactance voltage? in commutation
process.
What is the effect of frequency and supply voltage
on iron losses? ?
What are the effects of armature reaction?
Differentiate between ?armature voltage control?
and ??ux control? of do shunt motor.
What is the need of tertiary winding in a 3??
transformer?
Why short circuit test is performed on HV side of
transformer?
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i) What is the need of starter while starting the dc
motor? -
j) De?ne energy and co-energy.
SECTION - B
Attempt any Five questions of the followings
(5X 1 0=50)
a) -' Derive an expression for Reluctance torque in a
rotating electrical machine.
b) Explain the various phenomenon happening in
'electro mechanical energy conversion in rotating
electrical machines.
What are various losses that occur in d.c. machines? Also,
derive the condition for maximum ef?ciency of a d.c.
generator.
Draw the ?speed-torque characteristics? of d.c. shunt,
series and compound motors. A 200 V shunt motor has
Ra = 0.1 Q, Rf = 240 Q and rotational loss 236 W. On
full-load the line current is 9.8 A with the motor running
at 1450 r.p.m. Determine
a) The mechanical power developed.
b) The power output.
c) The load torque.
d) The full load efficiency.
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NEE-301
Explain the procedure of QC. and SC. tests for a
transformer. How different parameters of the transformer
can be determined from theses tests?
A 500 kVA, 11/0.43 kV, 3-? delta/star connected
transformer has on rated load. The HV copper loss of
2.5 kW and the LV loss of 2 kW and the total leakage
reactance of 0.06 per. unit. Find the ohmic values of the
equivalent resistance and leakage reactance on the delta
side.
a) Derive the relationship between magnetic ?eld
energy and co-energy for a singly-excited system.
b) Derive the emf equation for a dc generator.
. ' Two single-phase ?lmaces 1 and 2 are supplied at 80 V
by means of a Scott connected transformer combination
fed by a 3-phase 6600 V system. The voltage of furnace
1 is leading. Calculate the line currents on the 3-phase
side when the furnaces take 500 kW and 800 kW,
respectively -
a) At unity p.f.
b) Furnace 1 at unity p.f. and furnace 2 at 0.7 p.f.
(lagging).
What do you mean by ?PARALLEL OPERATION of 3-?
TRANSFORMERS?? Discuss the advantages and
disadvantages of parallel operation of 3-? transformers.
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NEE-301
SECTION-C
Note : Attempt any two questibns of the following.
(2 x 1 5=3 0)
10.? Write short notes on the following :
a) 3?d) to Z-d) connection of transformers.
b) 3-4) te 6-4) connection of transformers.
11. A 4-pole series wound fan motor draws an armature
current of 50 Amps, When running at 2000 rpm on a
230 V d.c. supply with four ?eld coils connected in
series. The four ?eld coils are then reconnected in two
parallel groups of two coils in series. Assuming ?ux/
pole to be proportional to the - exciting current and load
torque proportional to the square of the speed. Find the
new speed and arrhature Current.
- 12. a) Discuss the following tests'on d.c. machines -
i) Hopkinsdn?s test.
ii) D.C. resistance test.
b) Discuss the followingtest On l-? transformers.
i) Sumpener?s Back?to-back test.
ii) Polarity test.
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