2017 Fourth Semester B.Tech. Degree Examination' June (2013 Scheme)
ELEGTRICAL TECHNOLOGY (MP) Max. Marks: 100
Time:3 Hours PART_A
Answer all questions.
l,lnadcmachinelluxperpoledecreaseswithincreaseofload.JustifytheStatemenl. parameters' the speed equation of dc motor and explain various
2. Write down
3. Why do copper loss occurs in dc machine
for getting maximum 4. What type of load should be connected to transformer voltage regulation ? 5. Discuss the application of auto transformer'
3-phase induction motors ? 6. Why do we require starters for starting 7.
Whentheloadonanalternatorisvaried,itsterminalvottageisalsofoundtovary? why ?
8. What is the operation of capacitor start motor
locomotive' Draw the lunctional schematic of ac electric traction systems ? 10. What are the various types of motors used in
PART_B (Answer any one full question from each Module)'
Module-1 supplied 200A at
running at l OOO rpm 11. a) A separately excited generator, when. when the-speed drops to 800 rpm if l, is 125V. What wirr o" tnEloio "uirent armature resistance = 0'04 o and brush drop =
unchanged ? Assume b) Describe the open-circuit characteristics of dc
Derive an expression lor torque ol a dc motor. Hence draw torque vs current characteristics of dc shunt and dc series motors. b) Describe alltypes of losses in a shunt and compound wound generator. state which comprise constant loss. 10
Module-2 13. a) Explain briefly the operation of transformer and sketch phasor diagram on no-load.
b) Find all-day efficiency of a transformer having maximum efficiency ol gg% at 5 kVA at unity power factor and loaded as follows 12 hours - 2 kW at 0 5 pf tag 1
- at no-load.
12 kW at 0.8 pf tag
14. a) Discuss wilh circuit diagram any two method of starting a synchronous motor. b) Explain the constructional details of a squirrel cage and a slip-ring rotor induction motor. Compare merits and demerits of each type of motor.
Module-3 15. a) Derive emf equation ol ahernator and explain coil span factor and distribution factor. b) Explain the regulation of an alternator by emf method. 16. a) Explain V curves as applied to synchronous motors. b) Describe about stepper motorand also its advanrages, disadvantages and applications.
Module-4 17. a) Mention the various system of power supply in traction. b) Discuss the speed control methods of traction motors.
18. a) Explain the various braking methods used in traction motors.
b) Describe about any one type of electric welding.