Anna University Chennai 2010 B.E Mechanical Engineering Me2205 — electrical drives and control - Question Paper

Reg. No. :
B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010
Third Semester

Mechanical Engineering
ME2205 — ELECTRICAL DRIVES AND CONTROL

(Common to Chemical Engineering, Production Engineering)
(Regulation 2008)
Time: 3 hours Maximum: 100 Marks
ans ALL ques.

PART A — (10 × two = 20 Marks)

1. State the advantages of Electric Drive.
2. provide the formula for computing power requirement for a liner movement.
3. Write down the torque formula of a DC shunt motor and provide the significance
of flux.
4. A 6-pole, 3-phase induction motor operating on a 50 Hz supply has rotor
emf frequency as two Hz. Determine
(a) slip and
(b) the rotor speed.
5. Why are centrifugal switches given on many 1-phase induction motors?
6. Draw the block diagram of soft starter for an induction motor.
7. Compare the chopper control and phase control schemes for DC motor drives.
8. State the various methods of speed control of DC series motor.
9. What is advantage of v/f speed control of Induction Motor?
10. Draw the block diagram of speed control scheme for a slip ring Induction
motor.

PART B — (5 × 16 = 80 Marks)

11. (a) (i) Briefly discuss the different factors that will influence the option of
an electrical drive. (Marks 8)
(ii) discuss the method of estimating equivalent continuous power
rating of a motor for short time load applications. (Marks 8)
Or
(b) (i) discuss the various classes of motor duty with the equations. (Marks 8)
(ii) The temperature rise of motor after operating for 30 minutes on full
load is 20°C and after a different 30 minutes it becomes 30°C on the
identical load. obtain the final temperature rise and time constant. (Marks 8)

12. (a) (i) From electrical characteristic, derive the mechanical characteristic
of DC series motor. (Marks 8)
(ii) discuss the dynamic braking of DC shunt motor with the needed
diagram and equations. (Marks 8)
Or
(b) (i) Derive the Speed-Torque characteristic of 3-phase slip ring
induction motor. (Marks 8)
(ii) discuss the principle operation of capacitor begin and run 1-phase
Induction Motor. (Marks 8)

13. (a) (i) With a neat diagram discuss the operation of 4 point starter.
Also mention the advantages of this over a 3 point starter. (Marks 12)
(ii) Draw the control circuit for time limit acceleration of DC shunt
motor. (Marks 4)
Or
(b) State the different starting methods of squirrel cage induction motor.
discuss any 2 of them. (Marks 16)

14. (a) (i) discuss the operation of armature control of a DC shunt motor. (Marks 8)
(ii) Draw and discuss the 4 quadrant speed control of DC motor
using different choppers. (Marks 8)
Or
(b) (i) With the block diagram discuss the operation of armature and field
control of DC motor drive using controlled rectifiers. (Marks 12)
(ii) Name the various flux control methods adopted for DC series
motor. (Marks 4)

15. (a) discuss the operation of speed control techniques employed for 3-phase
squirrel cage induction motor. (Marks 16)
Or
(b) What is meant by slip power recovery scheme? discuss with the
necessary diagram. (Marks 16)

Earning:   Approval pending.