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Reg. No. :

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010

Third Semester

Electronics and Communication Engineering

EC2201 ELECTRICAL ENGINEERING

(Regulation 2008)

Time: Three hours Maximum: 100 Marks

Answer ALL Questions

PART A (10 2 = 20 Marks)

1. What are the conditions to be fulfilled for the self-excitation of a dc shunt

generator?

2. What are the functionS of interpoles and how are the interpoles windings

connected?

3. The emf per turn of a single phase, 6.6 kV/440 V, 50 Hz Transformer is

approximately 12 V.

Calculate

(a) the number of turns in the HV and LV windings and

(b) the net cross-sectional area of the core for a maximum flux density of

1.5 T.

4. Define voltage regulation of a transformer.

5. Why cannot an induction motor run at synchronous speed?

6. Why are single phase induction motors not self-starting?

7.

What are the causes of faulty starting of a synchronous motor?

8. What are the applications of stepper motors?

9. Why are insulators used with overhead lines?

10. Define skin effect.

Question Paper Code :E 3071

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14. (a) (i) Derive the emf equation of an alternator. Discuss the effect of

winding factor on the induced emf.

(ii) Explain the speed-torque characteristics of a reluctance motor.

Or

(b) (i) A 500 kVA, 3.3. kV, 3-phase, star-connected alternator is found to

give a short circuit current of 290 A at normal field current. Its

effective winding resistance per phase is 0.7 . Estimate the full

load of voltage regulation by EMF method for 0.8 pf lagging.

(ii) Explain the speed-torque characteristics of a hysteresis motor.

15. (a) (i) Draw the single diagram of a typical a.c. power supply scheme.

(ii) With a neat sketch, explain the intersheath grading of cables.

Or

(b) (i) Explain briefly the advantages of EHVAC transmission over

EHVDC transmission.

(ii) Draw the layout of a substation with the main equipments.

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