EX-402 RGPV B.Tech
Electrical Machine-I (EM)
Previous year papers and the official syllabus are free to read, no account needed.
Previous Year Papers
6 papers, latest Jun 2025
- EX-402 paper, Jun 2025
- EX-402 paper, Dec 2024
- EX-402 paper, Jun 2024
- EX-402 paper, Nov 2023
- EX-402 paper, Jun 2023
- EX-402 paper, Jun 2022
Syllabus, notes and important questions for EX-402
Syllabus units
Topics as the official RGPV syllabus lists them.
Unit 1 Transformer‑I 15 topics
- Working principle
- e.m.f. equation
- Construction
- Phasor diagrams
- Equivalent circuit
- Voltage regulation
- Losses
- Separation of hysteresis and eddy current losses
- Efficiency
- Tests: open circuit and short circuit, load, Sumpner’s test
- Condition for maximum efficiency and regulation
- Power and distribution transformer
- All‑day efficiency
- Excitation phenomenon
- Autotransformer: working, advantages, equivalent circuit and phasor diagram
Unit 2 Transformer‑II 6 topics
- Three‑phase transformer: construction, groups and connections, working and applications
- Scott connection
- Parallel operation of transformers: application, advantages, requirement and load sharing
- Tap changers
- Cooling, conservator and breather
- Pulse and high‑frequency transformers
Unit 3 Three‑phase Induction Motor‑I 10 topics
- Working principle
- Construction
- Comparison of slip‑ring and squirrel‑cage motors
- Steady‑state analysis
- Phasor diagram and equivalent circuit
- Power‑flow diagram
- Torque‑speed and power‑speed characteristics
- Losses and efficiency
- No‑load and block‑rotor test
- Circle diagram
Unit 4 Three‑phase Induction Motor‑II 9 topics
- Starting of squirrel‑cage and slip‑ring motors
- Power‑factor control
- Cogging & crawling
- Double‑cage & deep‑bar induction motor
- Impact of unbalanced supply and harmonics on performance
- Speed control
- Braking
- Induction generator
- Applications
Unit 5 Single‑Phase Motors 6 topics
- Single‑phase induction motor: double revolving field theory, equivalent circuit and its determination, performance calculation
- Starting methods and types of single‑phase induction motors: working principle and applications
- Comparison with three‑phase induction motor
- Single‑phase A.C. series motor
- Servo motors
- Linear induction motor
Exam insights
Counted from 6 past EX-402 papers.
Marks asked per paper, by unit
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Unit 1 Transformer-I 28 marks
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Unit 2 Transformer-II 20 marks
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Unit 3 Three phase Induction Motor- I 24 marks
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Unit 4 Three phase Induction Motor-II 16 marks
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Unit 5 Single Phase Motors 18 marks
Average marks of the questions from each unit in one paper. You answer only some of them, so the total is more than the paper’s maximum.
Asked again and again
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Explain the Scott / T-T connection for 3-phase to 2-phase (and 2-phase to 3-phase) conversion with circuit and phasor diagrams, including balanced/unbalanced operation and teaser winding ratio.
Asked 5 times: 2026, 2024, 2023, 2022
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Explain why a single-phase induction motor is not self-starting using double revolving field theory and principle of operation.
Asked 5 times: 2026, 2023, 2022, 2020, 2019
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Explain the conservator and breather in transformers.
Asked 4 times: 2026, 2025, 2024, 2020