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EndsemMay 20242019 patternSE Electrical

Electrical Machines-1 SPPU Endsem Question Paper May 2024

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

Open the PDFMost repeated Electrical Machines-1 questions
Subject code
203146
Pattern
2019 pattern
Exam
Endsem
Session
May 2024
Max. marks
70
Time
2½ Hours
Semester
IV
Paper code
[6261]-12

Printed for: S.E.(Electrical Engineering)

Instructions to the candidates

  1. Solve Q1 or Q2, Q3 or Q4, Q5 or Q6, Q7 or Q8.
  2. Figures to the right indicate full marks.
  3. Neat diagrams must be drawn wherever necessary.
  4. Use of non-programmable calculator is allowed.
  5. Assume suitable additional data if necessary.

Questions

  1. Q1

    1. a)

      State features of wave winding.

      [4]
    2. b)

      Derive the torque equation of DC motor by usual notations.

      Also asked:Nov 2024

      [6]
    3. c)

      A 6 pole, Lap wound DC shunt motor takes armature current of 110 Ampere at 480 volt. It has armature resistance of 1 Ohm and total 864 armature conductors.The flux per pole is 0.05 Weber. Calculate- i) Mechanical power developed in armature ii) Gross torque iii) Speed of the motor

      [8]

  2. Q2

    1. a)

      Sate the material used and function of following parts of a DC machine- i) Armature core ii) Brushes

      [4]
    2. b)

      Draw the power flow diagram of DC motor. Write respective expressions of power and power loss for respective blocks.

      [6]
    3. c)

      What is armature reaction in DC Machines? Explain the effects of armature reaction with suitable diagrams. Suggest the remedial measure on it.

      [8]

  3. Q3

    1. a)

      Explain why DC Series motor should not be started on - No load condition?

      [3]
    2. b)

      Sketch & explain the Torque - Armature current characteristics of DC shunt motor.

      Also asked:Nov 2025 ·May 2025 ·Nov 2023

      [6]
    3. c)

      Draw the connection diagram of 4 point starter used for DC shunt motor & explain the function of i) Hold on coil & ii) Over load coil.

      Also asked:May 2025

      [8]

  4. Q4

    1. a)

      What is meant by reactance voltage in case of commutation in DC machines?

      [3]
    2. b)

      Draw the connection diagram & explain the speed control of DC shunt motor by flux control method.

      Also asked:May 2025 ·Nov 2023

      [6]
    3. c)

      A DC series motor is running at 350 rpm at 220V, taking a current of 25Amp. The motor armature plus field resistance is 1 Ohm. Calculate - i) the resistance to be added in series to reduce the speed to 250 rpm at constant torque. ii) The power wasted in the resistor.

      [8]

  5. Q5

    1. a)

      A 4-pole, 3phase induction motor connected to 50 HZ supply. If the machine runs at 3% slip at full-load, determine i) Rotor speed ii) Frequency of rotor currents iii) Frequency of rotor currents at stand still iv) Speed of rotating magnetic field

      [4]
    2. b)

      Obtain the torque equation of induction motor under running condition & there of derive the condition of maximum torque under running condition

      Also asked:May 2025

      [6]
    3. c)

      Draw torque-slip characteristics of 3-ph induction motor & explain i) Stable and unstable operating region ii) maximum torque iii) torque ,when slip is one.

      Also asked:May 2025

      [8]

  6. Q6

    1. a)

      Draw a neat sketch of squirrel cage induction motor, label all the parts and explain its constructional details.

      [4]
    2. b)

      With suitable phasor diagrams elaborate the concept of rotating magnetic field in case of 3 phase induction motor

      [6]
    3. c)

      A 4 - pole, 50 Hz, 3 - phase induction motor gives output power of 14710 Watt. It has friction and windage losses of 2% of the output. The full - load slip is 3%. Calculate the i) Rotor cu. loss and ii) Rotor input

      [8]

  7. Q7

    1. a)

      Draw equivalent circuit of 3 Phase induction motor ,name all parameters involved in it.

      [3]
    2. b)

      With the help of circuit diagram explain procedure to conduct - No load test and blocked rotor test on 3 phase squirrel cage induction motor.

      [6]
    3. c)

      Draw the connection diagram of star-delta starter & explain the starting and running operation of 3-ph induction motor.

      Also asked:May 2025

      [8]

  8. Q8

    1. a)

      Compare star-delta starter and Rotor Resistance starter on any 4 poins.

      [8]
    2. b)

      Draw the circle diagram & write the procedure to find full load current, p.f, full load slip, locate the points for slip = 0 and slip = 1. Assume rotor Cu loss = stator Cu loss. 

      [9]