EC 2201 Electrical Engineering
PART A — (10 × 2 = 20 Marks)
1. What are the functions of yoke in a D.C. machine?
2. List the methods of speed control of a D.C. shunt motor.
3. Write down the emf equations of a single phase transformer.
4. Give the expression for percentage voltage regulation of a single phase transformer.
5. Define the slip of a three phase induction motor.
6. List the types of starters used to start three phase induction motors.
7. What are the two types of synchronous machines?
8. Give the applications of stepper motors.
9. Why are high voltages preferred for the transmission of electrical power?
10. List the components in a substation.
PART B — (5 × 16 = 80 Marks)
11. (a) (i) With a neat sketch explain the constructional details of a D.C. machine. (12)
(ii) Draw and explain the internal and external characteristics of a
D.C. shunt generator. (4) Or
(b) (i) Derive the torque equation of a D.C. motor. (6)
(ii) With a neat sketch explain the operation of a three point starter for a D.C. motor. (10)
12. (a) Explain the principle of operation of a single phase transformer and its behaviour on loaded condition with phasor diagram. (16)
Or
| (b) | (i)
(ii) |
Develop the equivalent circuit of a transformer. (8)
Explain the O.C. and S.C. tests done on a single phase transformer. |
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|
(8)
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| 13. | (a) | (i) | With neat sketches explain the construction of three phase slip ring and squirrel cage induction motors. (10) |
| (ii) | Compare the slip ring and squirrel cage rotors. (6) |
Or
(b) (i) Explain the auto transformer and star delta starters used to start the three phase induction motors. (8)
(ii) Explain the principle of operation of a shaded pole single phase induction motor. (8)
| 14. | (a) | (i) | Derive the expression | for the induced emf of a | synchronous |
| generator. |
(8)
|
Or
| (b) | (i) | Explain the method of obtaining the voltage regulation | of a |
| synchronous generator using EMF method. | (10) | ||
| (ii) | Explain the construction and operation of a hysterisis motor. | (6) |
| 15. | (a) | (i) | Explain the structure of a electrical power system indicating | the |
| generation, transmission and distribution section. | (10) | |||
| (ii) | Draw and explain the layout of a single bus bar substation. | (6) |
Or
(b) (i) Discuss the advantages and disadvantages of EHVAC and EHVDC
systems. (10)
(ii) Explain the construction of any one type of cables used for EHV
systems.
