Showing posts with label Electrical Engineering. Show all posts
Showing posts with label Electrical Engineering. Show all posts

Anna University - Electrical Engineering (EE) - 2011 November / December Question Paper

B.E /B.Tech DEGREE EXAMINATION NOVEMBER / December 2011
B.E. - Electronics and Communication Engineering
Third Semester .
ELECTRICAL ENGINEERING
(Regulation 2010)

 Time: Three hours
Maximum: l00 marks
Answer ALL questions

PART A (10 * 2 = 20 marks )
1. Distinguish between shunt and series field coil construction in DC machine?
2. What is the necessity of starter in dc motors?
3 What are the applications of step up and step down transformers ?
4. Define regulation and efficiency of the transformer.
5 Why an induction never runs at its synchronous speed ?
6 What is the function of a capacitor in single phase induction motor?
7. What is hunting ? how can it be prevented?
8 What are the advantages of stepper motor ? Give the applications of stepper motor?
9 What are the major electrical equipments used in the power system?
10.How cables are classified according to the voltage?

PART B - (5 x 16=80 marks)

11. (a) (i) Sketch and explain the speed-current, speed-torque and torque-current characteristics of a DC shunt and series motor (8)

(ii) Derive the expression for emf generated in d.c. machine (8)

Or 
(b) (i) Explain in detail about the ward-leonard sistem of speed control of DC motor. (8)

(ii) Draw a neat sketch and explain a 3 point starter. (8)

12. (a) (i) Draw and explain the no load vector diagram of ideal transformer and practical transformer. (8)

(ii) Enumerate the various losses in a transformer. Derive the condition for maximum efficiency. (8)
(b) (î) Derive the of single phase two winding transformers. (6)

(ii) A 250/500 V , 50 Hz single phase transformer gave the following test result:
SC test : 20V, 12  A , 100 W with low voltage winding shorted.
OC test : 250V, 1A , 80 W with high voltage winding shorted.

Obtain the equivalent circuit parameters and draw the equivalent circuit referred to primary.

13. (a) (i)List the differences between squirrel cage and slip ring induction motors (8)

(ii) Derive the torque equation of a three phase induction motor. Sketch the torque-slip characteristics of a 3-phase IM.

b.(i) Discuss the various methods of speed control in a 3-phase IM. (8)

(ii) Explain the working principle of single phase induction motor. Why single phase induction motor is not self starting. (8)

14. (a) (i) Explain the construction and working principle of motor. (8)

(ii) Define voltage regulation. Explain the two methods used to determine voltage regulation of alternators. (8)

Or
(b) Write short notes on:  (16)
(i) reluctance motor.
(ii) stepper motor.
(iii hysteresis motor.

15 (a) (i) Draw the structure of power system with single line representation. Show its essential constituent sections (8)

(ii) What are the advantages and / disadvantages of HVDC Transmission? (8)
Or

(b) (i) Explain in detail various types of insulators and their applications to power transmission. (8)

(ii) Draw the schematic layout of a substation and explain. (8)
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Anna University - Electrical Engineering (EE) - May / June 2007 Question Paper

B.E./B.Tech. DEGREE EXAMINATION, MAY/ JUNE 2007.
Third Semester
Electronics and Communication Engineering
EE 253 — ELECTRICAL ENGINEERING
Time : Three hours      Maximum : 100 marks
Answer ALL questions.

PART A — (10 x 2 = 20 marks)

1. Write the expression for determining real, reactive and apparent power in a
three phase circuit?
2. Define voltage regulation.
3. Write the speed equation of a dc machine.
4. Name any two non-loading method of testing de machines.
5. What are all the advantages of induction motor over other motors?
6. Draw an approximate equivalent circuit of an induction motor.
7. Mention some of the special features on synchronous machine.
8. Write any two applications of reluctance motor.
9. Name the divisions of electric power system.
10. What are the choices of site for the coal fired thermal power station?

PART B — (5 X 16 = 80 marks)

11. (a) (i) The voltage across the lines of s three phase star connected generator is 11 KV. The generator supplies a 6 MW load at 0.8 lagging power factor. Calculate the active and reactive components in each of the generator?         (8)
(ii) Draw the circuit diagram and explain the theory of three phase power measurement by two wattmeter method.        (8)

Or

(b) (i) Explain the principle of operation of Single phase Transformer (8)
(ii) A 150 KVA, 2400/240 V Transformer has R2 = 0.002 ohm, X2 = 0.45 ohm. Calculate the primary induce emf.    (8)

12. (i) Explain the principle of operation of DC motor. (8) 

(ii) Draw the schematic diagram ofall types of DC machines. (8)

Or

Explain the Swinburne's test of predetermination of efficiency of a DC Machine as generator and motor. (16) 

13. (a) Develop an equivalent circuit of an induction motor from first principle. (16)
Or 

(b) Explain the various starting methods of squirrel cage induction motor.  (16) 

14. (a) With the help of schematic diagrams, explain the constructional details of synchronous machine. (16) 

Or

(b) Calculate the percentage voltage regulation for a three phase star connected 2500 KVA, 6600V alternator operating at full load and (1) 0.8 power factor lagging, (ii) 0.8 power factor leading. The per phase synchronous reactance is 10.4 ohm. Neglect armature resistance. (16)

15. (a) Draw the schematic diagram depicting the structure of a power system and explain each major divisions. (16)

Or

(b) Write short notes on: (16)
(i) HVDC transmission
(ii) Underground cables.
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Anna university - ELECTRICAL ENGINEERING (EE) - Nov / Dec 2007 Question Paper


B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2007. 
Third Semester 
Electronics and Communication Engineering
EE 253 — ELECTRICAL ENGINEERING 

Answer ALL questions.
PART A — (10 x 2 = 20 marks) 

1. List down the different types of losses in a Transformer.
2. What are the necessary tests to determine the equivalent circuit of a transformer?
3. In every DC motor, a generator action occurs. Justify.
 4. Why a DC series motor should not be started on no load?
5. Can a three phase Induction motor run at synchronous speed? Why?
6. A 3 phase, 6 pole, 50 Hz induction motor has a slip of 3% at full load, determine the speed at full load.
7. Why is the Ampere turns method called as Optimistic method?
8. What is meant by synchronous reactance?
9. What are the advantages of EHVDC transmission over AC transmission?
10. Define string efficiency of an insulator.


PART B — (5 x 16 = 80 marks) 

11. (a) (i) Explain how 3 phase power can be measured using two watt meters method.
(ii) Obtain the expression for the total power and load power factor in terms of wattmeter Wi and W2.

 Or

(b) (i) Derive the condition for maximum efficiency of a transformer.
(ii) For a 40 KVA, single phase transformer, the iron losses and full load copper losses are 350 W and 400 W respectively. Find the efficiency at unity power factor on full load and determine the load for maximum efficiency.

12. (a) (i) Draw the Speed-Torque characteristics of different types of DC motors.
(ii) Explain the different methods of speed control of DC motors.

 Or

 (b) (i) Explain the Swinburne's test to predetermine the efficiency of a DC machine.
(ii) Obtain the expression for efficiency of the DC machine both as a motor and as a generator using the observations from the Swinburne's test.

13. (a) (i) Explain the construction and principle of operation of a 3 phase Induction motor.
(ii) What is the condition for maximum torque under starting and running condition?

Or

(b) (i) Why are the starters used for the starting of an induction motor?
 (ii) Explain the construction and operation of a Star-delta starter.

14. (a) (i) Derive an expression for the induced emf of an alternator.
 (ii) Explain the EMF method to determine the voltage regulation of an alternator.

Or


(b) (i) Explain the construction and working of a Variable reluctance stepped motor.
(ii) Give the expression to find the step angle and resolution of a stepper motor.

15. (a) (i) Sketch and explain the structure of an electric power station and the voltage level at various points.
 (ii) What are the advantages and disadvantages of underground cables?

Or

(b) What are the various types of insulator used in Overhead Transmission system and explain them in detail.


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Anna University-Electrical Engineering-Electrical Engineering Question Bank

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Anna University - Electrical Engineering - Question Bank


Anna University - Question Bank
UNIT – I
PART – A
  1. Define electric motor.
  2. Define electric generator.
  3. Define excitation.
  4. What are the methods of excitation?
  5. What do you mean by self excited machine?
  6. What do you mean by separately excited machine?
  7. State the function of commutator.
  8. What do you mean by commutation?
  9. What is the purpose of brushes?
  10. By which material yoke can be manufactured?
  11. Why the brushes are made upon carbon?
  12. What are the types of self excited generator?
  13. Define shunt generator.
  14. Define series generator.
  15. Define compound generator.
  16. Draw the open circuit characteristics of dc separately excited generator.
  17. What do you mean by magnetization curve?
  18. Draw the load characteristics of separately excited dc generator.
  19. Draw the characteristics for DC shunt generator.
  20. Draw the characteristics of DC series generator.
  21. Draw the characteristics of DC compound generator.
  22. What is the principle of operation of dc generator?
  23. Write down faradey's law of electromagnetic induction.
  24. What is the principle of operation of DC motor?
  25. State lenz's law.
  26. How Lenz's law is helpful for the operation of DC motor?
  27. Write the significance of back e.m.f.
  28. Define back e.m.f.
  29. Write the e.m.f. equation of DC generator.
  30. Write down the voltage equation of DC motor.
  31. Write the torque equation of DC motor.
  32. Draw the characteristics of DC shunt motor.
  33. Draw the characteristics of DC series motor.
  34. Draw the characteristics of DC compound motor.
  35. Differentiate differentially compound and cumulatively compound motor.
  36. What are the applications of DC shunt motor?
  37. What are the applications of DC series motor?
  38. What are the applications of DC compound motor?
  39. Why shunt motor is called as constant speed machine?
  40. Why starter is needed in DC motor?
  41. What is the advantage of 4 point starter over 3 point starter?
  42. State the function of no volt coil.
  43. State the function of over load release.
  44. What is the advantage of conducting Swin-burne's test?
  45. Draw the diagram of ward-leanord system of speed control.
  46. By which method, we can control the speed of the motor below the base speed?
  47. By which method, the speed control of the DC motor be above the base speed?
  48. What are the various methods of speed control of DC motor?
  49. Differentiate armature voltage control method and field flux control method.
  50. What do you mean by brake test?
PART – B
  1. Explain in detail the constructional details of DC machine.
  2. Derive the e.m.f. equation (8)
  3. Draw and explain the characteristics of DC generator.
  4. Derive the torque equation/
  5. Write down the significance of back e.m.f.
  6. Write down the principle of operation of DC motor.
  7. Draw and explain the characteristics of DC motor.
  8. Draw and explain 3 point starter.
  9. What is the draw back in 3 point starter and how it is overcome in 4 point starter?
  10. Explains the procedure of swin burne's test.
  11. Draw and explain the speed control methods of DC shunt motor.
  12. Explain in detail about the ward-leonard system of speed control of DC motor.
  13. Problem.

UNIT – II
PART – A 
  1. State the principle of operation of transformer.
  2. What are the types of transformer according to its construction?
  3. Differentiate core type transformer and shell type transformer.
  4. Write down the e.m.f equation of transformer.
  5. Write down the transformation ratio.
  6. Define magneting current component.
  7. Define working current component.
  8. Draw the vector diagram of transformer an no load.
  9. How the resistance of the secondary be referred in the primary?
  10. Draw the approximate equivalent circuit of the transformer.
  11. Draw the vector diagram for the transformer under resistive load.
  12. Draw the vector diagram for the transformer under inductive load.
  13. Draw the vector diagram of the transformer under comparative load.
  14. When the transformer is said to be ideal?
  15. Define voltage regulation of transformer.
  16. Define voltage regulation up.
  17. Define voltage regulation down.
  18. By conducting no load test, which losses can be found out?
  19. Which losses can be found out by conducting short circuit test?
  20. What are the tests to be conducted on the transformer?
PART - B
  1. Derive the e.m.f. equation of transformer.
  2. Explain in detail about the transformer on no load.
  3. Draw and explain ideal transformer. Draw its vector diagram.
  4. Obtain the equivalent circuit of the transformer by conducting suitable tests.
  5. Draw and explain in detail about the transformer an load.
  6. Derive the regulation formula for the transformer.
  7. Explain in detail about the testing procedures for the transformer.
  8. Problem.

UNIT – III
PART – A 
  1. Write the working principle of induction motor.
  2. How RMF is produced with the help of 3 phase supply?
  3. Define slip.
  4. Write the working principle of 3f induction motor.
  5. Why 3f induction motor is called as rotating transformer?
  6. Can the rotor speed of induction motor be synchronous speed?
  7. What are the types of induction motor?
  8. Write down the torque equation of 3f induction motor.
  9. Draw the slip-torque characteristics.
  10. Draw the speed-torque characteristics.
  11. State the relation between P2, Pc and Pm.
  12. Draw the Power flow diagram of 3 phase induction motor.
  13. Draw the equivalent circuit of 3 f induction motor.
  14. Why starter is necessary in AC induction motor?    
  15. What are the types of starters available to start 3 f induction motor?
  16. Why single phase induction motor is not self starting?
  17. How single phase induction motor is made to start?
  18. How the rotor is classified in 3f induction motor?
  19. How Rmf is produced in the stator of the induction motor
  20. What is Rmf?
PART - B
1. Explain the constructional details of 3 f induction motor.
2. How Rmf is produced with the help of 3 f AC supply?
3. Explain in detail the principle of operations of 3 phase induction motor.
4. Explain the procedure to obtain the equivalent circuit of 3 phase induction motor.
5. Derive the torque equation of 3 phase induction motor.
6. Draw and explain the characteristics of 3 phase induction motor.
7. Explain in detail about (i) Star-delta starter (ii) Auto transformer starter (iii) DOL starter.
8. Write short notes on single phase transformer.
9. Why single phase induction motor is not self starting? Explain the methods available to start the motor.
10. Write short notes on speed control of 3 f induction motor.

UNIT IV
PART – A 
  1. What are the types of synchronous machines?
  2. What is the basic principle of operation 3f alternator?
  3. Why stationary armature is there in 3f alternator?
  4. Write down the e.m.f. equation of alternator.
  5. What are the types of 3 f alternator?
  6. Define voltage regulation of alternator?
  7. What are the methods to find out voltage regulation?
  8. Why synchronous impedance methods is called as pessimistic method?
  9. What are the methods to find out voltage regulation
  10. Why synchronous impedance method is called as pessimistic method?
  11. Define synchronous impedance.
  12. Why ampere-turns method is called as optimistic method?
  13. Draw the phasor diagram for voltage regulation in synchronous impedance method.
  14. How emf is induced in brushless alternator?
  15. What is the function of rotating diode assembly in brush can alternator?
  16. What do you mean by brushless excitation?
  17. How reluctance motor is running?
  18. What is the operating principle of hysteresis motor?
  19. What are the types of stepper motor?
  20. How do you find step angle in stepper motor?
  21. Give the application of stepper motor.
PART - B
  1. Derive the emf equation of alternator.
  2. Write down the procedure of finding voltage regulation of alternator using synchronous impedance method.
  3. Write down the procedure for finding voltage regulation using ampere-turns method.
  4. Explain in detail the construction of synchronous machine.
  5. Write short notes on (i) Brushless alternator (ii) Reluctance motor (iii) Hysteresis motor (iv) Stepper motor.
UNIT – V
PART – A
  1. What are the various sources of electric power generating system?
  2. What is the purpose of step up transformer in electrical power system?
  3. What do you mean by carona loss?
  4. What is meant by Ferranti effect?
  5. What are the advantages of AC transmission?
  6. What are the advantages of DC transmission?
  7. What are the types of distribution system?
  8. What is EHUAC?
  9. Define EHUDC.
  10. What is the purpose of circuit breakers.
  11. Define insulators.
  12. Why the transmission is done through under ground cable?
  13. What are the advantages of under ground cables?
  14. What are the types of under ground cables?
  15. What are types of insulators?
  16. What is pin insulator? Where it is used?
  17. What is stay insulator? Where it is used?
  18. What are the purposes of insulator?
  19. Define service mains.
  20. Define grid.
  21. Differentiate feeders and distributors.
PART - B
  1. Explain in detail, the single line diagram of electrical power system.
  2. Explain in detail the various types of transmission and distribution systems.
  3. Distinguish EHUAC and EHUDC systems.
  4. Explain in detail the substation lay out.
  5. Write short notes as (i) Insulators (ii) cables.
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Electrical Engineering Lab Questions


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