EE Unit 3 Notes AKTU (BEE101)

AKTU · BTECH · Semester 1, 2 · Fundamentals of Electrical Engineering · Unit 3 · Notes

AKTU Fundamentals of Electrical Engineering (BEE101) Unit 3 notes for B.Tech Semester 1/2 – Transformers. Topics: Magnetic Circuits, Ideal and Practical…

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Unit 3: Transformers – AKTU syllabus topics

  • Magnetic Circuits
  • Ideal and Practical Transformer: Ideal Transformer, Practical Transformer, Equivalent Circuit of Transformer
  • Transformer Losses and Efficiency: Core and Copper Losses, Transformer Efficiency, Voltage Regulation

Most asked AKTU PYQ questions from Unit 3

  1. Q2c. State the significance of voltage regulation of transformer. A 4kVA, 200/400V, 50Hz single phase transformer has equivalent resistance referred to primary as 0.15Ω. Calculate: (i) Total copper losses on full load. (ii) Efficiency at full load 0.9 pf lagging. (iii) Efficiency at half load 0.8 pf… (10 marks, 2021-22)
  2. Q5a. What is the purpose of an equivalent circuit of a transformer? Obtain the approximate equivalent circuit of a transformer as referred to the primary with all necessary parameters. (10 marks, 2021-22)
  3. Q5b. A 20kVA, 2000V/200V, single-phase, 50Hz transformer has primary resistance 1.5Ω and reactance 2Ω. Secondary resistance 0.015Ω and reactance 0.02Ω. No load current 1A at 0.2 pf. Determine: (i) Equivalent resistance, reactance and impedance referred to primary. (ii) Supply current. (iii) Total… (10 marks, 2021-22)
  4. Q1f. Draw the phasor diagram for an ideal transformer on no load. (2 marks, 2021-22)
  5. Q2a. (i) Derive the EMF equation of a transformer. (ii) Derive the condition for maximum efficiency in single phase transformer. (10 marks, 2021-22)
  6. Q5a. A transformer on no-load has a core loss of 50W, draws a current of 2A and has an induced emf of 230V. Determine the no-load power factor, core loss current and magnetizing current. Also, calculate the no-load circuit parameters of the transformer. Neglect winding resistance and leakage flux. (10 marks, 2021-22)
  7. Q5b. Explain the performance and principal of operation of single phase transformer. (10 marks, 2021-22)
  8. Q2c. The following results were obtained on a 5 kVA, 2400/120V transformer: Open circuit test 120V, 9.65A, 396W instrument on l.v. side. Short circuit test 92V, 20.8A, 810W instrument on h.v. side. Determine: (i) the circuit constants (ii) efficiency at half load, 0.8 p.f. lagging (iii) regulation at… (7 marks, 2025-26)
  9. Q5a. Explain operating principle of transformer and derive the equation for induced emf in a two-winding transformer. Also discuss the term regulation and efficiency w.r.t. transformer. (7 marks, 2025-26)
  10. Q5b. The efficiency of a 400 kVA 1-ϕ transformer is 98.77%, when delivering full load at 0.8 p.f. and 99.13% at half of the full load and unity power factor. Calculate (i) Iron loss (ii) Full load copper loss. (7 marks, 2025-26)

AKTU paper codes: BEE101, BEE201, KEE101, KEE201

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