B.TECH. DEGREE EXAMINATION, NOVEMBER 2008

Seventh Semester
Branch: Electrical and Electronics Engineering
ELECTRICAL DRWES AND CONTROL (E)
Answer all questions.


Time : Three Hours Maximum: 100 Marks
Part A
Each question carries 4 marks.
1. Describe single phase rectifiers with motor load.
2. What are the DC drives ? Briefly explain.
3. List the advantages of chopper fed drives.
4. Compare single, two and four quadrant chopper drives.
5. Discuss speed control of 3-phase induction motors.
6. Describe the principle of slip power recovery scheme.
7. Explain the working of voltage source inverter.
8. Compare current source, voltage source inverter.
9. Discuss the principle of vector control.
10. Discuss the principle of synchronous motor control.
(l0x 4=: 40marks)
Part B
Each question carries 12 marks.
11. Explain in detail speed control of DC motors.
Or
12. Explain the operation of a single-phase fully controlled rectifier control of d.c. separately excited motor. Get the armature voltage for continuous conduction.
13. Explain with neat circuit diagram and waveform of 3-phase fully controlled bridge rectifier drives.
Or
14. Explain in detail dual converter fed DC motor drives.

15. Discuss about stator voltage control of induction motors. Give the various controller configurations.
Or
16. Explain:
(a) Constant torque and constant power control.
(b) Slip power recovery scheme.
17. Explain v/f, elf, flux weakening schemes of control.
Or
18. Explain with circuit diagram a current source inverter fed induction motor drive.
19. Explain:
(a) Speed control of synchronous motors.
(b) Principles of synchronous motor control.
Or
20. Explain self-controlled synchronous motor drive using load commutate thyristor inverter.
[5 x 12 = 60 marks]


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