Mahatma Gandhi University (MGU) 2005 B.Tech Electrical and Electronics Engineering Electrical Machines - III (E) - exam paper

B.TECH DEGREE exam
Seventh Semester
Branch : Electrical and Electronics Engineering
ELECTRICAL MACHINES – III (E)
Model for November 2005
Time: 3 Hours Maximum: 100 Marks

PART – A
ans all ques.
every ques. carry equal marks

1. Develop the torque formula for the 3-phase induction motor
2. Develop the equivalent circuit of a 3-phase induction motor
3. Explain the necessity of starter for starting a 3-phase induction motor.
4. With the help of a neat sketch, define the star delta method of starting of a 3-phase squirrel cage induction motor.
5. Discuss briefly the operation of an induction generator.
6. Explain the operation of a capacitor start-capacitor run single phase induction motor.
7. Write notes on universal motor.
8. Discuss the operation and application of a reluctance motor.
9. Describe with the help of diagrams the constructional details and action of a double cage induction motor.
10. Explain the action of scherbius advancer (10 X four = 40 Marks)

PART – B
ans all ques.
every ques. carry equal marks

11. Discuss the constructional details of a 3-phase slip-ring and cage induction motors.
Or
12. (a) discuss how circle diagrams is drawn from no load and blocked rotor test.
(b) Draw the torque-slip characteristic of 3-phase induction

13. Calculate tile steps m a five step rotor starter for a 3-phase slip ring induction motor. The slip at the maximum starting current is 2% with slip-rings short circuited and the resistance per rotor phase in 0.015 ohm.
Or
14. Discuss various methods of speed control of a 3-phase cage induction motor, indicating the merits and demerits.

15. Discuss the construction, operation and application of a synchronous induction motor.
Or
16. Explain why a single-phase induction motor is not self-starting. Draw the equivalent circuit of a single – phase induction motor and discuss.

17. Discuss the construction and operation of a single-phase series motor.
Or
18. Discuss the construction and working of a repulsion begin induction motor.

19. Discuss with the aid of a diagram the construction and operation of discharge motor.
Or
20. Describe the principle of operation and application of a linear induction motor. (5 X 12 = 60 Marks)

Earning:   Approval pending.