Question Paper: Electrical Machines Question Paper - May 2016 - Electronics Engineering (Semester 4) - Mumbai University (MU)
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## Electrical Machines - May 2016

### MU Electronics Engineering (Semester 4)

Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

### Solve any three question Q1.(a,b,c,d)

1(a) Define the slip of an induction motor. Explain its significance. 5 marks

1(b) Explain the construction of permanent magnet syhronous motor. 5 marks

1(c) Draw and explain block diagram V/f control using converter- inverter scheme for 3 phase induction motor. 5 marks

1(d) Explain back emf equation of dc motor. 5 marks

2(a) Explain the principle of operation of capacitor start and capacitor run single phase induction along with slip-torque charateristics and applications. 5 marks

2(b) Explain construction and working of multistack variable reluctance stepper motor. 5 marks

3(a) A 4 pole 3 phase 50Hz star connected induction motor has ful load slip of 6% calculate full load speed of the motor. 5 marks

3(b) Explain double field revolving theory in single phase induction motor. 5 marks

4(a) Classify the brushless DC motor and explain in detail unipolar brushless Dc motor. 5 marks

4(b) A 800W,
115V,
60Hz capacitor start motor draw 13.8 A from the supply at rated load if the efficiency is 70% and rated speed is 1800 rpm, Calculate
i) Input power at rated load
ii) Power factor at rated load
iii) Rated motor horse power
5 marks

5(a) Explain diffefrent speed control methods of DC short motor. 5 marks

5(b) Explain construction and working of 3 phase squirrel cage induction motor. 5 marks

6(a) Write short note on