Anna University of Technology Tirunelveli 2008-3rd Sem B.E Electronics & Communication Engineering ./B.Tech , EMR/EMR 2009Electronics and Communication Engineering EC 2201 — ELECTRICAL ENG

Time : 3 hours Maximum : 100 Marks
ans ALL ques.
PART A — (10 × two = 20 Marks)
1. elaborate 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. provide the expression for percentage voltage regulation of a single phase transformer.
5. describe the slip of a 3 phase induction motor.
6. List the kinds of starters used to begin 3 phase induction motors.
7. elaborate the 2 kinds of synchronous machines?
8. provide 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 discuss the constructional details of a D.C. machine. (12)
(ii) Draw and discuss the internal and external characteristics of a D.C. shunt generator. (4)
Or
(b) (i) Derive the torque formula of a D.C. motor. (6)
(ii) With a neat sketch discuss the operation of a 3 point starter for a D.C. motor. (10)

12. (a) discuss the principle of operation of a single phase transformer and its behaviour on loaded condition with phasor diagram. (16)
Or
(b) (i) Develop the equivalent circuit of a transformer. (8)
(ii) discuss the O.C. and S.C. tests done on a single phase transformer.
(8)

13. (a) (i) With neat sketches discuss the construction of 3 phase slip ring and squirrel cage induction motors. (10)
(ii) Compare the slip ring and squirrel cage rotors. (6)
Or
(b) (i) discuss the auto transformer and star delta starters used to begin the 3 phase induction motors. (8)
(ii) discuss 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)
(ii) discuss the construction and operation of a reluctance motor. (8)
Or
(b) (i) discuss the method of obtaining the voltage regulation of asynchronous generator using EMF method. (10)
(ii) discuss the construction and operation of a hysterisis motor. (6)

15. (a) (i) discuss the structure of a electrical power system indicating the generation, transmission and distribution part. (10)
(ii) Draw and discuss the layout of a single bus bar substation. (6)
Or
(b) (i) explain the advantages and disadvantages of EHVAC and EHVDC systems. (10)
(ii) discuss the construction of any 1 kind of cables used for EHV systems. (6)

Earning:   Approval pending.