2009 Kerala University B.Tech Industrial Engineering Fourth Semester B. Tech. Degree Examination Question paper

PART – A

1. What are the effects of armature reaction in D.C. generator ?
2. Derive the condition for maximum efficiency of a D.C. Motor.
3. Sketch the load characteristics of D.C. compound generator.
4. Explain the need of starter for D.C. Motor.
5. Derive the e.m.f.equation of a transformer.
6. How are alternators classified ?
7. Explain the braking of traction motors.
8. Differentiate between slipring and squirrel cage induction motors. What are their
relative advantages ?
9. Discuss an application of universal motor.
10. Explain the principle of dielectric heating. (10×4=40 Marks)

PART – B

Module – I
11. a) A D.C. shunt motor has full load rating of 7.355 KW,1000 r.p.m, 250V. The
resistances of armature and field are 0.5 ??and 250?? respectively. Efficiency at
full load is 85%. Determine i) No load current ii) the speed when motor takes
10A and iii) armature current when the motor develops 49.05Nm.
b) With suitable sketches explain various types of D.C. generators.
OR
12. a) A belt driven 60 KW shunt wound generator running at 500 r.p.m.is supplying
full load to a busbar at 200V. At what speed will it run if the belt breaks and the
machine continues to run taking 5 KW from the busbar ? The armature and field
resistances are 0.1 ??and 100?? respectively. Take brush contact drop = 2V.
b) Derive the torque equation of D.C. Motor.
Module – II
13. a) Obtain the equivalent circuit of a 200/2000V single phase transformer having the
following test results.
O.C. test : 200V, 6.2A 360W on 1.v. side
S.C. test : 75V, 18A 600W on h.v. side
b) Discuss the speed control of traction motors.
OR
14. a) Explain the construction and working of synchronous motor. Explain how
synchronous motors can be used for improving power factor.
b) What are current transformers ? Explain its construction and use.
Module – III
15. a) A 746 KW , 3 phase, 50Hz 16 poles induction motor has a rotor impedance of
(0.02 + j 0.15) ?? at standstill. Full load torque is obtained at 360 r.p.m.
Calculate : 1) The ratio of maximum torque to full load torque ii) The speed for
maximum torque and iii) Rotor resistance to be added to get maximum torque at
start.
b) Explain the working of induction furnace.
OR
16. a) Explain the principle of working of stepper motor.
b) A 3-phase, 400V induction motor gave the following test results.
No - load test : 400 V, 1250 W, 9 A
Blocked rotor test : 150 V, 4K W, 38 A
Draw the circle diagram. If the normal rating is 14.91 KW find the full load
current and slip. (3×20=60 Marks)