AKTU Electrical Machines-I · Important Questions 2026Source: ryzenstudy.com PYQs
BEE402 Electrical Machines-I Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 5 AKTU Electrical Machines-I papers (2021-22–2025-26): 115 questions grouped into 56 distinct questions, 29 of which were asked in more than one paper.
- of marks were repeat questions
- 77%
- of marks were repeat questions
- questions asked in 2+ papers
- 29
- questions asked in 2+ papers
- papers analysed (2021-22–2025-26)
- 5
- papers analysed (2021-22–2025-26)
- units, mapped to current syllabus
- 5
- units, mapped to current syllabus
How much of the paper repeats?
- Repeats are real: when we checked each newer BEE402 paper against the papers before it, on average 77% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 78% of marks were repeats (12 of 17 repeated questions were in our top list).
- 2024-25 paper: 66% of marks were repeats (12 of 15 repeated questions were in our top list).
- 2025-26 paper: 87% of marks were repeats (13 of 19 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 76% of the next paper's marks — picking the same number of topics at random would have covered about 67%.
Across 10 subjects and 23 papers we tested, 43% of marks repeated earlier questions on average.
1.Unit-wise most-asked questions
Ranked by how many papers asked them, then by how recently. Click a paper to open it.
Unit 1: Pre- Requisites
22% of past marks| Question | Asked |
|---|---|
| Derive the expression for force and torque in a singly excited magnetic system. | Asked 4× |
| Explain the principle of electromechanical energy conversion using a suitable block diagram, energy balance equation and energy flow diagram. | Asked 4× |
| Define co-energy in an electromechanical system. | Asked 3× |
| Show that the field energy in a linear magnetic system is given by (see original paper). | Asked 2× |
Unit 2: Pre- Requisites
21% of past marks| Question | Asked |
|---|---|
| Discuss commutation and methods of improving commutation. | Asked 4× |
| Explain the armature reaction in DC generators using armature and field MMF waveforms. Describe the effects of armature reaction. | Asked 4× |
| Draw the internal and external characteristics of the DC shunt generator. Also explain (i) why the external characteristics turn backwards (ii) the concept of voltage build-up and critical field resistance in a DC shunt generator. | Asked 2× |
| Write the emf equation of a DC motor. Explain each term. | Asked 2× |
Unit 3:
20% of past marks| Question | Asked |
|---|---|
| Differentiate between 3-point and 4-point starters. | Asked 4× |
| Explain Swinburne’s test to calculate no-load losses in a DC machine. State its limitations over Hopkinson’s test. | Asked 3× |
| Discuss the need for starters in the operation of DC motors. | Asked 3× |
| A 250 V DC shunt motor has an armature resistance of 0.5 Ω and a field resistance of 250 Ω. When driving a constant torque load at 600 rpm, the motor draws 21 A. What will be the new speed of the motor if an additional 250 Ω resistance is inserted in the field circuit? | Asked 2× |
Unit 4: Pre- Requisites · Single Phase Transformer
20% of past marks| Question | Asked |
|---|---|
| A 200 kVA, 2000/440 V, 50 Hz, single-phase transformer gave the following test results: O.C. Test (HV): 2 kV, 1.75 kW, 1.8 A; S.C. Test (LV): 13 V, 1 kW, 300 A. (i) Calculate the parameters of the equivalent circuit as referred to H.V. side (ii) Determine voltage regulation and efficiency at full-load, 0.8 power factor lagging. | Asked 4× |
| The maximum efficiency of a 100 kVA, 1100/440 V, 50 Hz transformer is 96%. This occurs at 75% of full load at 0.8 power factor lagging. Calculate the efficiency of the transformer at half load and at 0.6 power factor lagging. | Asked 4× |
| Explain Sumpner’s test in transformer with a neat diagram. | Asked 2× |
| Draw the phasor diagram of an ideal transformer at no-load condition. | Asked 2× |
Unit 5: Pre- Requisite · Three Phase Transformers
18% of past marks| Question | Asked |
|---|---|
| What is V-V connection? Show that the open delta connection has a kVA rating of 57.7% of the rating of the normal delta-delta connection. | Asked 5× |
| Give conditions for parallel operation of three phase transformers. | Asked 4× |
| Describe the 3-phase to 2-phase conversion in transformers with a suitable diagram. Also, derive the expression for positioning of neutral point. | Asked 3× |
| Explain Star/Delta connection in three phase transformers. | Asked 3× |
2.Topic weightage: which topics carry the marks
Blue = Tier 1 + Tier 2 (topics that carried ~80% of past marks). Grey = the rest. It shows where marks have gone, not a promise of what comes next.
Transformer tests · U4
8.3% (cum 8%)
Speed control of DC motors · U3
8.3% (cum 17%)
Open delta and phase conversion · U5
8.3% (cum 25%)
Commutation and interpoles · U2
7.1% (cum 32%)
Energy and co-energy · U1
6.9% (cum 39%)
Efficiency and voltage regulation · U4
6% (cum 45%)
Starters for DC motors · U3
5.4% (cum 50%)
Parallel operation and load sharing · U5
4.9% (cum 55%)
Armature reaction · U2
4.8% (cum 60%)
Force and torque from energy · U1
4.7% (cum 65%)
Three-phase connections and vector groups · U5
4.7% (cum 69%)
DC generator characteristics · U2
4.7% (cum 74%)
Electromechanical energy conversion principle · U1
4.5% (cum 79%)
Transformer construction and equivalent circuit · U4
4.4% (cum 83%)
Efficiency and testing of DC machines · U3
4.2% (cum 87%)
EMF and torque in cylindrical air gap · U1
3.4% (cum 91%)
DC machine construction and EMF equation · U2
3.1% (cum 94%)
Singly and doubly excited systems · U1
2.3% (cum 96%)
DC motor characteristics and applications · U3
2% (cum 98%)
Autotransformer · U4
1% (cum 99%)
Armature windings · U2
0.9% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Transformer tests · Unit 4 · Tier 1 | 4/5 | 8.3% |
| Speed control of DC motors · Unit 3 · Tier 1 | 5/5 | 8.3% |
| Open delta and phase conversion · Unit 5 · Tier 1 | 5/5 | 8.3% |
| Commutation and interpoles · Unit 2 · Tier 1 | 5/5 | 7.1% |
| Energy and co-energy · Unit 1 · Tier 1 | 4/5 | 6.9% |
| Efficiency and voltage regulation · Unit 4 · Tier 1 | 5/5 | 6% |
| Starters for DC motors · Unit 3 · Tier 1 | 5/5 | 5.4% |
| Parallel operation and load sharing · Unit 5 · Tier 2 | 5/5 | 4.9% |
| Armature reaction · Unit 2 · Tier 2 | 4/5 | 4.8% |
| Force and torque from energy · Unit 1 · Tier 2 | 4/5 | 4.7% |
| Three-phase connections and vector groups · Unit 5 · Tier 2 | 4/5 | 4.7% |
| DC generator characteristics · Unit 2 · Tier 2 | 3/5 | 4.7% |
| Electromechanical energy conversion principle · Unit 1 · Tier 2 | 4/5 | 4.5% |
| Transformer construction and equivalent circuit · Unit 4 · Tier 2 | 4/5 | 4.4% |
| Efficiency and testing of DC machines · Unit 3 · Tier 3 | 4/5 | 4.2% |
| EMF and torque in cylindrical air gap · Unit 1 · Tier 3 | 3/5 | 3.4% |
| DC machine construction and EMF equation · Unit 2 · Tier 3 | 3/5 | 3.1% |
| Singly and doubly excited systems · Unit 1 · Tier 3 | 2/5 | 2.3% |
| DC motor characteristics and applications · Unit 3 · Tier 3 | 2/5 | 2% |
| Autotransformer · Unit 4 · Tier 3 | 1/5 | 1% |
| Armature windings · Unit 2 · Tier 3 | 2/5 | 0.9% |
3.Paper pattern (2025-26)
| Section | Questions | Rule |
|---|---|---|
| A | 7 × 2 marks | Attempt all |
| B | 5 × 7 marks | Attempt any 3 |
| C | 10 × 7 marks | Attempt any 1 |
4.In the syllabus, never asked yet
Low priority, but read them once — a new paper can always start here.
- Magnetic materials and BH curve · U1
- Stepper and servo motors · U3
- Excitation phenomenon and harmonics · U4
- Three winding transformers · U5
5.Study order
- 1Transformer tests (Unit 4, Tier 1)
- 2Speed control of DC motors (Unit 3, Tier 1)
- 3Open delta and phase conversion (Unit 5, Tier 1)
- 4Commutation and interpoles (Unit 2, Tier 1)
- 5Energy and co-energy (Unit 1, Tier 1)
- 6Efficiency and voltage regulation (Unit 4, Tier 1)
- 7Starters for DC motors (Unit 3, Tier 1)
- 8Parallel operation and load sharing (Unit 5, Tier 2)
- 9Armature reaction (Unit 2, Tier 2)
- 10Force and torque from energy (Unit 1, Tier 2)
- 11Three-phase connections and vector groups (Unit 5, Tier 2)
- 12DC generator characteristics (Unit 2, Tier 2)
- 13Electromechanical energy conversion principle (Unit 1, Tier 2)
- 14Transformer construction and equivalent circuit (Unit 4, Tier 2)
FAQ
Which units of BEE402 carry the most marks?
Unit 1 (Pre- Requisites, 22% of past marks) and Unit 2 (Pre- Requisites, 21% of past marks).
Do AKTU Electrical Machines-I questions repeat?
Yes. On average 77% of the marks in each newer BEE402 paper came from questions already asked in an earlier paper, and 29 questions have appeared in more than one paper.
How is this list made?
Every question from the 5 papers (2021-22–2025-26) was mapped to the current AKTU syllabus and grouped with the same question from other years. Questions are ranked by how many papers they appeared in, then by how recently.
Study this subject
Note: this is based on past AKTU papers, not a guarantee. Questions are mapped to the current syllabus; topics that are no longer in the syllabus are left out.