EC2201 Electrical Engineering Nov / Dec 2013 Important Questions - Anna University ECE 3rd Semester Important Questions Nov Dec 2013
1. Explain the construction of a DC machine with neat diagram.
2. A dc shunt generator has a terminal voltage of 160V and no-load induced emf of 168 V. The resistances of armature and field are 0.03Ω and 20Ω. Find the armature current, field current and load current. Neglect armature reaction.
3. Explain the characteristics of series, shunt and compound motors.
4. Explain the ward leonard method of speed control of dc shunt motor.
5. Derive the emf equation of transformer.
6. Derive the emf equation of DC Generator.
7. A 1Ф transformer is rated at 240/120 V, 50 Hz. Find voltage and frequency of secondary at noload. (a) If primary voltage is 120V, 25Hz (b) if primary voltage is 240V dc.
8. Deduce the equivalent circuit of 1Ф transformer.
9. A 1Ф transformer is rated at 10kVA, 50 Hz. The secondary rated voltage is 240V and the turns ratio is 10. The resistance and leakage reactance as referred to primary are 8.4Ω and 13.7Ω respectively. Find voltage regulation at full load and power factors of 0.8 lagging, 0.8 leading and unity.
10. Explain the principle operation of 3Ф induction motor.
11. A 3Ф, 6 pole, 50 Hz cage motor is running with a slip of 4% . Find speed of the rotating field relative to the stator winding, motor speed and frequency of emf induced in the rotor.
12. Briefly explain the starting of squirrel cage motor using star-delta starter.
13. Discuss the operation and types of 1 Ф IM with neat circuit diagrams with speed-torque
characteristics
14. Discuss about the types of alternators
15. Explain the construction and operation of (a) Reluctance Motor (b) Hysteresis motor
16. Explain the construction and operation of (a) Stepper Motor (b) Brushless Alternators
17. Draw the one-line diagram of a typical power supply system. Mark all the components.
18. What are the advantages of dc transmission systems over ac transmission systems? Explain.
19. What are the main components used in Transmission and Distribution systems? Write down the functions of each.
20. Compare OH lines and UG cable systems.
21. A lap wound 6pole shunt generator supplies 10kW at a terminal voltage of 400 volts. The armature and shunt field are 0.12Ω and 200Ω respectively. Calculate the generated emf. Allow brush drop of 1V per brush. Also calculate the number of conductors if the speed is 1000RPM and flux per pole is 30mWb. Neglect armature reaction.
22. Explain the method of controlling speed of DC Shunt motor below and above the rated speed.
23. A 4 pole 250 Volts Shunt motor has 450 lap wound conductors. It takes 32 Amperes from a 250 Volts DC Supply and develops output power of 7500 Watts. The armature resistance and shunt field resistance values are 0.1Ω and 250Ω respectively. The flux per pole is 30mWb.Calculate the speed and torque developed by the motor in Nm.W
24. Mention the working principles of a Transformer. Also list the various applications of Transformers.
26. Explain the method of conducting O.C test and S.C test on Transformer. Why these tests are to be performed?
27. A 10 kVA Transformer having 1100 turns on High Voltage(H.V) side and 110 turns on Low
Voltage(L.V) side. If the H.V side is energized with 2200 Volts, 50 Hz, AC Supply. Calculate:
a. No-load voltage on L.V side
b. Full load H.V and L.V side current
c. Maximum value of flux in the core
28. Draw and explain the Torque-Slip characteristics of an Induction motor.
29. A 4pole 3 Ф Induction Motor is running at 1460 RPM on a 415 Volts, 50Hz power supply. Calculate the Speed of RMF and % of slip, frequency of rotor current.
30. List the various methods of controlling the speed of induction motors. Also explain any one method of speed control in detail.
31. Determine the method of determining the regulation of an alternator by MMF method.
32. Determine the method of determining the regulation of an alternator by Synchronous Impedance method.
33. List the various types of sub-station in a power system. Also specify the role of each sub-station.
34. List the various types of insulators. Also specify its applications.
35. List the various types of cables with neat diagram.
Note:
Refer all the solved university problems given in Bakshi book (Technical Publications) for the first three units.
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