Skip to content
EndsemNov 20242019 patternSE Electrical

Electrical Machines-1 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-1 questions
Subject code
203146
Pattern
2019 pattern
Exam
Endsem
Session
Nov 2024
Max. marks
70
Time
2½ Hours
Semester
IV
Paper code
[6352]-12

Printed for: S.E. (Electrical Engineering)

Instructions to the candidates

  1. Solve Q.1 or Q.2, Q.3 or Q.4, Q.5 or Q.6, Q.7 or Q.8.
  2. Figures to the right indicate full marks.
  3. Neat diagrams must be drawn wherever necessary.
  4. Assume suitable additional data, if necessary.
  5. Use of a non-programmable calculator is allowed.

Questions

  1. Q1

    1. a)

      Draw & Label a neat diagram showing constructional details of DC machine. Explain each parts.

      [9]
    2. b)

      A 500V,4 poles, wave connected DC shunt motor has 1200 armature conductors and useful flux/pole is 20 mWb. The armature and field winding resistance are 0.5ohm & 250ohm respectively. The Iron & Friction losses are 900W. At full load motor draw 20A. Calculate. i) Armature Torque ii) Shaft torque iii) Lost torque

      [9]

  2. Q2

    1. a)

      Explain Demagnetizing & Cross magnetizing effect of armature reaction on DC machine.

      [9]
    2. b)

      Derive Torque equation of DC motor with usual notation. Write Voltage and Current equation of DC shunt motor.

      Also asked:May 2024

      [9]

  3. Q3

    1. a)

      Draw and explain all three characteristics of DC shunt motors.

      [9]
    2. b)

      A 500V, 6pole DC shunt motor have armature & field winding resistance of 0.5ohm and 250ohm respectively. It draws a full load current of 20A from supply. If the rotational losses are 900W, calculate efficiency of motor.

      Also asked:Nov 2023

      [8]

  4. Q4

    1. a)

      Draw and explain all three characteristics of DC series motors.

      [9]
    2. b)

      What is necessity of starter for DC motor? Draw and explain Three point starter 2

      Also asked:Nov 2025

      [8]

  5. Q5

    1. a)

      Compare squirrel cage rotor & wound rotor three phase induction motor

      [6]
    2. b)

      A 3 phase, 50Hz, 4pole induction motor had slip of 4%. Calculate i) Synchronous speed ii) Frequency of rotor emf: If the rotor has a resistance of 1 ohm & standstill reactance of 4ohm calculate the rotor power factor. iii) Speed of motor iv) Power factor at standstill.

      [8]
    3. c)

      Explain effect of slip on rotor frequency and rotor current.

      [4]

  6. Q6

    1. a)

      Derive the torque of three phase induction motor and obtain the condition for maximum torque.

      [6]
    2. b)

      Three phase, 50Hz, 6pole induction motor develop a shaft torque of 150Nm at full load slip of 4%. The rotating losses are 300W & that of stator losses are 1.5KW Calculate. i) Rotor copper loss ii) Rotor gross output. iii) Efficiency at full load.

      [8]
    3. c)

      Draw and explain the torque-slip characteristics of three phase induction motor.

      [4]

  7. Q7

    1. a)

      Draw and explain approximate and exact equivalent circuit of an induction motor along with required equation.

      [9]
    2. b)

      Enlist the various types of starters for three phase induction motor. Explain Star- Delta starter along with merits and demerits.

      [8]

  8. Q8

    1. a)

      Explain V/f method of speed control of three phase induction motor.

      [8]
    2. b)

      With neat connection diagram explain No load & Blocked rotor test on three phase induction motor. 

      [9]