Jawaharlal Nehru Technological University Anantapur 2011 B.Tech Electrical and Electronics Engineering , utilization of electrical energy (r07) - Question Paper

IV B.Tech II Semester Examinations,APRIL 2011
UTILIZATION OF ELECTRICAL ENERGY
Electrical And Electronics Engineering
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks

1. (a) explain the features of DC arc welding.
(b) Enlist the advantages of AC arc welding machines. [8+8]
2. (a) discuss skin eect and pinch eect compare the performance of Ajax wyatt
and core-less furnace.
(b) Estimate the rating of induction, furnace to melt 2 tones of zinc in 1 hour
if it operates at an eciency of 70% specic heat of zinc = 0.1, latent heat of
fusion of zinc = 26.67 Kcal/kg. Melting point is 455 0C. [8+8]
3. explain in detail the different categories of light ttings employed for indoor lighting,
describing the application of every kind. [16]
4. (a) Dene:
i. Space to height ratio
ii. Specic output
iii. Coecient of utilization
iv. Coecient of re
ection.
(b) A room measuring 20m  15m is to be illuminated by 10 lamps and the
avg. illumination is to be 75 lux. Determine the MSCP of every lamp if the
utilization and depreciation factors are 0.5 and 0.8 respectively. [8+8]
5. Derive expression for:
(a) The tractive eort for propulsion of a train on level track
(b) The tractive eort for propulsion of a train up and down a gradient. [16]
6. explain the different factors on which nal option of traction system depends. [16]
7. Derive the expressions for the speed - Torque characteristics of dc shunt motor
under the subsequent conditions:
(a) Without control
(b) External resistance in the armature circuit
(c) External resistance in the eld circuit
(d) Armature shunted with resistance R.
Draw the typical characteristics for all the conditions. [16]
8. A train is to run ranging from 2 stations 1.6km apart at an avg. speed of 40kmph,
the run is to be made to a quadrilateral N-T curve. Maximum speed is to be
limited to 64 kmph, acceleration, to two kmphps, coasting retardation to 0.16, braking
retardation to 3.2, nd the duration of a acceleration, coasting and braking periods.

Earning:   Approval pending.