SRM University 2008 B.Tech Electrical and Electronics Engineering PEE201 -ELECTRICAL MACHINES-1 - Question Paper

B.Tech(PT) DEGREE EXAMINATION,DECEMBER 2008
1st Semester
PEE201-ELECTRICAL MACHINES-1
Time:3 Hours Max.Marks:100


ans ALL Qustions

PART-A(10*2=20 Marks)

1.What is hysteresis loss? How will you minimize it?

2.What is multiple excited system?give 1 example.

3.What is armatue raction?

4.Mention the kind of excitation in DC machine.

5.What is the use of starter?

6.At what condition,power developed in the DC machine is maximum?

7.How will you clasify Transformer based on construction?

8.Why the flux in the transformer are constant for all loading conditions?

9.Mention the varios losses in DC machine.

10.What is the use of polarity test?

PART-B(5*16=18 Marks)
11.a. Derive an expression for mechanical force developed in rotating machines.

(OR)
b. discuss the MMF developed in distributed winding

12.a..i Derive the emf formula DC generator.
ii. Draw and discuss the characteristics of compound generators.

(OR)
b. discuss he process of commutation in DC generator?Mention its kinds.

13.a. discuss the varios method of speed control of DC shunt motor.

(OR)
b. Draw and discuss the subsequent characteristics of DC series and shunt motor:
(i) Mechanical characteristics
(ii) Electrical characteristics

14.a. With relevent phasor diagram,explain the operation of single phase transformer on No load and loading conditions at various power factor.

(OR)
b. Compare auto transformer with 2 winding transformer.how will you convert to auto transformer in to step up or step down transformer?

15.a. discuss swimburne's test.How will pre determine the efficiency of DC generator and DC motor using this test? Mention its merits and demerits.
(OR)
b. A five K V A single phase transformer has 1000 watts and 2000 watts as iron losses and copper losses at full load and is operating at 0.8 pf logging .What is the maximum efficiency at wich the transformer works? Al so obtain the efficiency at half load and unity power factor.

Earning:   Approval pending.