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Reg. No. : ................................ Name : .....................................
Third Semester B.Tech. Degree Examination, June 2009 03-302 : ELECTRICAL TECHNOLOGY (TA) (2003 Scheme) Time : 3 Hours
Max. Marks : 100
Instruction : Answer all questions from Part A. PART – A 1. Explain the principle of operation of a transformer ? 2. What is an auto transformer ? What advantages are possessed by autotransformers ? 3. Derive the emf equation of a DC generator. 4. Explain the principle of operation of universal motors. 5. Explain the constructional details of a three phase Induction motor. 6. Explain the principle of operation of a stepper motor. 7. State the different types of single phase Induction motors and their applications. 8. Discuss the various types of electric braking. 9. What is the principle of operation of resistance furnace ? 10. What is the principle of dielectric heating ? Where is it used ?
(10×4=40 Marks)
PART – B Answer any 2 questions from each Module. Each question carries 10 marks. Module – I 11. Draw and explain phasor diagram of a single phase transformer under load at leading power factor. Hence explain the regulation of a transformer on leading power factor load ? P.T.O.
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12. A 12 pole dc generator has a simplex wave wound armature having 144 coils of 10 turns each. The resistance of each turn is 0.011 ohm, the flux per pole is 0.05 wb and speed is 200 rpm. a) What is the induced emf ? b) What is the armature resistance ? c) What is the induced counter torque on the shaft of the machine, if a 1000 ohm resistance is connected to its terminals ? Neglect the effect of armature resistance. 13. Describe the various methods of speed control of DC motors. Module – II 14. A 6 pole, 50 Hz, 3 φ Induction motor running on full load with 4% slip develops a torque of 165 N-m at its pulley rim. The friction and windage losses are 200 W and the stator copper and iron losses equal 1650 W. Calculate i) Rotor output ii) Rotor copper loss and iii) Efficiency at full load. 15. Derive the emf equation of an alternator considering the effect of distribution and short pitched coils. 16. Discuss the starting methods of synchronous motors. Module – III 17. With neat circuit diagram and phasor diagram explain the measurement of power in a three phase balanced ac circuit. 18. What are different welding methods ? Describe the method of resistance welding. 19. What are the different types of induction heating ? Explain core type induction heating with a neat diagram. –––––––––––––––––––––––