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ENEE 202Bachelor in Electrical Engineering · Semester 31 Paper Available

Electrical Machines

Past examination question papers and complete curriculum syllabus for Electrical Machines (ENEE 202), Bachelor in Electrical Engineering Semester 3 under Institute of Engineering (IOE), Tribhuvan University.

Past Question Papers (PDF)

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Note: This question paper file (4th sem) was archived from an IOE exam session for the common Electrical Machines curriculum.

4th-sem_Electrical Machines.pdf

IOE Past Examination Paper

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Most Frequently Asked Questions

Top recurring IOE board exam questions for Electrical Machines with verified mark schemes, formula notation, and recurrence frequency.

Showing 30 of 30 top repeated questions

Electromechanical Energy Conversion Principles

3 Questions
#1Repeated 3 Times[6 Marks]Electromechanical Energy Conversion Principles
Explain double-field revolving theory and cross-field theory for single-phase induction motors. Why is a single-phase induction motor not self-starting?
Appeared in:2082 Chaitra2080 Chaitra2076 Chaitra
#2Repeated 3 Times[8 Marks]Electromechanical Energy Conversion Principles
Describe the construction and working of single-phase induction motors: Split-phase, Capacitor-start, Capacitor-start capacitor-run, and Shaded-pole motors with their torque-speed curves.
Appeared in:2083 Baishakh2081 Bhadra2077 Chaitra
#3Repeated 3 Times[8 Marks]Electromechanical Energy Conversion Principles
Explain the principle of operation and V-curves and inverted V-curves of a synchronous motor. How can an over-excited synchronous motor be used as a Synchronous Condenser for power factor correction?
Appeared in:2082 Chaitra2080 Baishakh2076 Bhadra

Single-Phase Transformers and Equivalent Circuits

7 Questions
#1Repeated 4 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
Derive the EMF equation of a single-phase transformer ($E = 4.44 f N \Phi_m$). Draw the complete exact and approximate equivalent circuits referred to primary and secondary sides.
Appeared in:2083 Baishakh2081 Bhadra2079 Chaitra2076 Chaitra
#2Repeated 4 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
Describe Open Circuit (No-load) and Short Circuit tests on a single-phase transformer. How are core loss parameters ($R_0, X_0$) and equivalent winding impedance ($R_{eq}, X_{eq}$) determined from test data?
Appeared in:2082 Bhadra2080 Chaitra2077 Magh2075 Bhadra
#3Repeated 3 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
Define voltage regulation and efficiency of a transformer. Derive the condition for maximum efficiency and show that maximum efficiency occurs when copper loss equals iron loss ($P_{cu} = P_i$).
Appeared in:2082 Chaitra2080 Baishakh2078 Bhadra
#4Repeated 3 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
A $50\text{ kVA}, 2400/240\text{ V}, 50\text{ Hz}$ transformer gave test results: OC test (LV side): $240\text{ V}, 5.41\text{ A}, 186\text{ W}$; SC test (HV side): $48\text{ V}, 20.8\text{ A}, 617\text{ W}$. Find efficiency and voltage regulation at full load and $0.8$ power factor lagging.
Appeared in:2083 Baishakh2081 Chaitra2079 Baishakh
#5Repeated 3 Times[6 Marks]Single-Phase Transformers and Equivalent Circuits
What is an autotransformer? Derive an expression for the copper savings in an autotransformer compared to a two-winding transformer of the same rating ($W_{auto} = (1 - 1/a) W_{two-winding}$).
Appeared in:2082 Bhadra2081 Baishakh2078 Chaitra
#6Repeated 3 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
Explain parallel operation of single-phase and three-phase transformers. State essential and desirable conditions. Derive the load sharing formula between two transformers having unequal per-unit impedances.
Appeared in:2082 Chaitra2080 Chaitra2076 Chaitra
#7Repeated 3 Times[8 Marks]Single-Phase Transformers and Equivalent Circuits
Explain Scott Connection (T-T connection) of two single-phase transformers for 3-phase to 2-phase conversion. Prove that the teaser transformer requires a tapping at $86.6\%$ ($(\sqrt{3}/2)N_1$) of main winding turns.
Appeared in:2083 Baishakh2081 Bhadra2077 Chaitra

DC Generators and Operating Characteristics

4 Questions
#1Repeated 3 Times[6 Marks]DC Generators and Operating Characteristics
Derive the generalized EMF equation of a DC generator ($E = \frac{P \Phi Z N}{60 A}$). Compare Lap and Wave armature windings with respect to parallel paths ($A$), voltage rating, and current capability.
Appeared in:2081 Chaitra2079 Chaitra2075 Bhadra
#2Repeated 3 Times[8 Marks]DC Generators and Operating Characteristics
Explain armature reaction in DC machines. Describe its demagnetizing and cross-magnetizing effects on air-gap flux distribution. How are compensating windings and interpoles used to neutralize armature reaction?
Appeared in:2082 Bhadra2080 Baishakh2078 Chaitra
#3Repeated 3 Times[6 Marks]DC Generators and Operating Characteristics
Describe commutation in DC machines. What causes sparking at the commutator brushes? Explain methods of improving commutation: resistance commutation and EMF commutation (interpoles).
Appeared in:2083 Baishakh2082 Chaitra2080 Chaitra
#4Repeated 3 Times[8 Marks]DC Generators and Operating Characteristics
Explain the Open Circuit Characteristic (OCC) and Internal/External characteristics of separately excited, shunt, series, and compound DC generators. Explain the conditions for voltage build-up in self-excited shunt generators.
Appeared in:2081 Bhadra2079 Baishakh2077 Magh

DC Motors, Speed Control, and Braking

5 Questions
#1Repeated 3 Times[6 Marks]DC Motors, Speed Control, and Braking
Explain the principle of operation of a DC motor and significance of back EMF ($E_b = V - I_a R_a$). Derive the electromagnetic torque equation ($T = \frac{P \Phi Z I_a}{2\pi A}$).
Appeared in:2082 Bhadra2080 Baishakh2076 Bhadra
#2Repeated 3 Times[8 Marks]DC Motors, Speed Control, and Braking
Compare the torque-speed and torque-armature current characteristics of DC Shunt, Series, and Compound motors. Why should a DC series motor never be started on no-load?
Appeared in:2083 Baishakh2081 Chaitra2078 Bhadra
#3Repeated 3 Times[8 Marks]DC Motors, Speed Control, and Braking
Explain the methods of speed control of DC shunt motors: (a) Armature resistance control, (b) Field flux control, and (c) Ward-Leonard speed control system. Compare their efficiency, speed range, and cost.
Appeared in:2082 Chaitra2080 Chaitra2079 Chaitra
#4Repeated 3 Times[8 Marks]DC Motors, Speed Control, and Braking
Why is a starter required for starting a DC motor? Draw a neat schematic diagram of a 3-point starter and 4-point starter, explaining the protective functions of No-Volt Release (NVR) and Overload Release (OLR) coils.
Appeared in:2083 Baishakh2081 Bhadra2078 Chaitra
#5Repeated 3 Times[8 Marks]DC Motors, Speed Control, and Braking
Describe Swinburne's test and Hopkinson's regenerative test for finding the efficiency of DC machines. What are the advantages and limitations of each test?
Appeared in:2082 Bhadra2080 Baishakh2077 Chaitra

Three-Phase Induction Motors

7 Questions
#1Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Explain the production of rotating magnetic field in a 3-phase induction motor with constant magnitude ($1.5 \Phi_m$) rotating at synchronous speed ($N_s = 120f/P$).
Appeared in:2081 Chaitra2079 Chaitra2076 Chaitra
#2Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Define slip ($s = \frac{N_s - N}{N_s}$). Derive the torque-slip equation for a 3-phase induction motor: $T = \frac{3}{\omega_s} \frac{V_1^2 (R_2'/s)}{(R_1 + R_2'/s)^2 + (X_1 + X_2')^2}$. Sketch the torque-slip curve from $s = 0$ to $s = 1$.
Appeared in:2083 Baishakh2082 Chaitra2080 Chaitra
#3Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Derive the condition for maximum starting torque and maximum running (breakdown) torque ($s_{mT} = R_2'/\sqrt{R_1^2 + (X_1 + X_2')^2}$). Show that maximum torque is independent of rotor resistance.
Appeared in:2082 Bhadra2080 Chaitra2077 Magh
#4Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Explain the power flow diagram in a 3-phase induction motor: relate Rotor Input ($P_{in}$), Rotor Copper Loss ($P_{cu}$), and Mechanical Power Developed ($P_m$) as $P_{in} : P_{cu} : P_m = 1 : s : (1 - s)$.
Appeared in:2081 Bhadra2079 Baishakh2076 Bhadra
#5Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Describe No-load test and Blocked Rotor test on a 3-phase squirrel cage induction motor to determine its equivalent circuit parameters. How is the circle diagram constructed from test results?
Appeared in:2082 Chaitra2080 Baishakh2078 Bhadra
#6Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Explain starting methods of 3-phase induction motors: Direct-on-Line (DOL), Star-Delta starter, Autotransformer starter, and Rotor resistance starter. Compare starting torque and starting current ratios.
Appeared in:2083 Baishakh2081 Chaitra2079 Baishakh
#7Repeated 3 Times[8 Marks]Three-Phase Induction Motors
Explain speed control methods of 3-phase induction motors: (a) Stator voltage control, (b) Variable frequency control (V/f control), (c) Pole changing method, and (d) Rotor resistance control.
Appeared in:2082 Bhadra2081 Baishakh2078 Chaitra

Synchronous Generators (Alternators)

4 Questions
#1Repeated 3 Times[8 Marks]Synchronous Generators (Alternators)
Derive the EMF equation of a 3-phase alternator considering pitch factor ($k_p = \cos(\alpha/2)$) and distribution factor ($k_d = \frac{\sin(m\beta/2)}{m\sin(\beta/2)}$): $E_{ph} = 4.44 k_p k_d f \Phi T_{ph}$.
Appeared in:2081 Chaitra2079 Chaitra2075 Bhadra
#2Repeated 3 Times[8 Marks]Synchronous Generators (Alternators)
Explain voltage regulation of an alternator. Describe Synchronous Impedance (EMF) method, Ampere-Turn (MMF) method, and Potier Triangle (Zero Power Factor - ZPF) method for determining regulation.
Appeared in:2082 Bhadra2080 Baishakh2078 Chaitra
#3Repeated 3 Times[8 Marks]Synchronous Generators (Alternators)
Explain Blondel's Two-Reaction Theory for salient pole synchronous machines. Draw the phasor diagram and derive the power-angle expression showing electromagnetic and reluctance power components ($P = \frac{E V}{X_d}\sin\delta + \frac{V^2(X_d - X_q)}{2 X_d X_q}\sin 2\delta$).
Appeared in:2083 Baishakh2082 Chaitra2080 Chaitra
#4Repeated 3 Times[8 Marks]Synchronous Generators (Alternators)
Explain synchronizing of alternators to infinite busbars. Describe dark lamp, bright lamp, and synchroscope methods. What happens when field excitation or prime mover input is changed after synchronization?
Appeared in:2081 Bhadra2079 Baishakh2077 Magh

Curriculum Syllabus & Course Topics

Sourced from TU curriculum portal
Full Syllabus (PDF)
Chapter-wise Units & Micro-Syllabus Topics (7 Units)

  1. 1. Electromechanical Energy Conversion Principles

    5

  2. 2. Single-Phase Transformers and Equivalent Circuits

    8

  3. 3. Three-Phase Transformers and Connections

    6

  4. 4. DC Generators and Operating Characteristics

    6

  5. 5. DC Motors, Speed Control, and Braking

    6

  6. 6. Three-Phase Induction Motors

    8

  7. 7. Synchronous Generators (Alternators)

    6

Examination Scheme & Marks Distribution

Evaluation Structure

  • Final Board Theory Exam: 60 Marks (Pass mark: 24)
  • Internal Assessment: 40 Marks (Pass mark: 16)
  • Practical / Lab Exam: 25 or 50 Marks (Continuous lab evaluation + viva, where applicable)

* This is the general current IOE 60/40 scheme; verify course-specific details in the syllabus above.

Exam Preparation Guidelines

  • Review the available past examination paper to understand question styling, typical derivation topics, and marks allocation.
  • Practice drawing labeled circuit schematics, deriving transfer functions, and showing systematic mathematical steps.
  • Structure answers with labeled diagrams, concise bullet points, and highlight final answers in numerical solutions.

Frequently Asked Questions (Electrical Machines)

Q: How can I download Electrical Machines past question papers?

You can preview or download the Electrical Machines question papers (PDF) directly using the built-in viewer on this page with zero redirects or paywalls.

Q: What is the pass mark for Electrical Machines?

The general current scheme is a 60-mark final theory exam and a 40-mark internal assessment, with pass marks of 24 and 16. Verify the course-specific syllabus above.

Q: Where can I find the complete syllabus for this subject?

The available chapter-wise syllabus and topic breakdown is indexed in the Syllabus section above, with links to the curriculum PDF source.

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