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EndsemNov 20242019 patternTE Electrical

Electrical Machines-II SPPU Endsem Question Paper Nov 2024

All 8 questions from this SPPU endsem paper, as printed. Read them here or open the PDF.

Open the PDFMost repeated Electrical Machines-II questions
Subject code
303143
Pattern
2019 pattern
Exam
Endsem
Session
Nov 2024
Max. marks
70
Time
2½ Hours
Semester
I
Paper code
[6353]-63

Printed for: T.E. (Electrical Engineering)

Instructions to the candidates

  1. Solve Q1 or Q2, Q3 or Q4, QS or Q6, Q7 or Q8.
  2. Figures to the right indicate full marks.
  3. Neat diagrams must be drawn wherever necessary.
  4. Assume suitable data if necessary.
  5. Use of non-programmable calculator is allowed.

Questions

  1. Q1

    1. a)

      Draw V curve of synchronous motor. Show under excited, overexcited and critical excitation regions on it.

      Also asked:May 2025

      [4]
    2. b)

      State different methods to start 3 phase synchronous motor. Explain damper winding method with neat diagram.

      [6]
    3. c)

      Explain with relevant phasor diagrams the operation of synchronous motor at constant load and variable excitation condition.

      Also asked:May 2025

      [8]

  2. Q2

    1. a)

      Draw and explain torque angle characteristics of 3 phase synchronous motor.

      [4]
    2. b)

      Explain the following terms related to loading of 3 phase synchronous motor - i) load angle or torque angle ii) Internal angle iii) power factor angle. Show these angles by drawing relevant phasor diagram for leading power factor.

      Also asked:May 2025

      [6]
    3. c)

      The input to an 11000V, 3 phase, star connected synchronous motor is 60 A. The effective resistance and synchronous reactance per phase are respectively 1 ohm and 30 ohms. Calculate the power supplied to motor at 0.8 pf lagging and induced emf for a power factor of 0.8 leading. Determine the angle of retardation at 0.8 pf leading. 2

      [8]

  3. Q3

    1. a)

      Draw speed vs torque characteristics of 3 phase induction motor for three frequencies such that f1>f2>f3.

      [3]
    2. b)

      Calculate the stepping angle for a 3 phase 24 pole PM stepper motor. If its stepping frequency is 300 steps per second, calculate the motor speed.

      [6]
    3. c)

      Explain operation three phase induction motor as an induction generator. State its advantages and applications.

      Also asked:May 2025

      [8]

  4. Q4

    1. a)

      State important features of energy efficient induction motor.

      Also asked:May 2025

      [3]
    2. b)

      Explain with suitable diagram speed control of three phase induction motor by cascade control.

      Also asked:Nov 2025 ·May 2025 ·May 2024 ·Nov 2023 ·May 2023

      [6]
    3. c)

      Describe with suitable diagram construction & working of permanent magnet DC motor. State its advantages and applications.

      Also asked:May 2025

      [8]

  5. Q5

    1. a)

      What do you mean by universal motor? Draw its torque vs speed characteristics on A C and D C operation.

      Also asked:Nov 2025 ·May 2025

      [3]
    2. b)

      With suitable diagram, explain conductively compensated A C series motor.

      Also asked:Nov 2025 ·May 2025 ·May 2024 ·Nov 2023 ·May 2023

      [6]
    3. c)

      Discuss the modifications necessary in design and construction of D C series motor so that it can work satisfactorily on A C supply as a universal motor.

      Also asked:May 2025

      [8]

  6. Q6

    1. a)

      How unidirectional torque is produced when a D C series motor is operated on A C supply?

      [3]
    2. b)

      Compare compensated A C series motor with non-compensated A C series motor.

      Also asked:Nov 2025 ·May 2025 ·May 2024 ·Nov 2023 ·May 2023

      [6]
    3. c)

      A universal motor having resistance of 30 ohms and inductance of 0.5 H. When connected to 250 V D C supply, it takes 0.8 A and runs at 2200 rpm. Determine its speed, torque and power factor when connected to a 250 V, 50 Hz A C supply and taking same current of 0.8 A. 3

      [8]

  7. Q7

    1. a)

      This part has equations that don’t show as text. Open the PDF to read it.

      [4]
    2. b)

      With suitable diagram explain blocked rotor test performed on single phase capacitor start induction motor.

      Also asked:May 2025

      [6]
    3. c)

      A 2 pole 230 V 50 Hz single phase induction motor has the following constants referred to the stator : R1 = 2.2 ohms; Xl = 3 ohms ; R’2 = 3.8 ohm ; X’2 = 2.1 ohms; Xm = 86 ohms Calculate the stator current, power factor and input power, when the motor is operating at a full load of 2820 rpm.

      [8]

  8. Q8

    1. a)

      A 0.25 HP 110 V split phase single phase induction motor takes a current of 4 A lagging the supply voltage by 15 degrees for the starting winding and a current of 6 A lagging the voltage by 40 degrees for its main winding. Calculate i) the total current and ii) the power factor

      [4]
    2. b)

      Explain double field revolving theory for single phase induction motor with suitable phasor diagrams.

      [6]
    3. c)

      This part has equations that don’t show as text. Open the PDF to read it.

      [8]