The GATE Grind

GATE Electrical Machines: Single phase transformer: equivalent circuit, phasor diagram, open circuit and short circuit tests, regulation and efficiency – Previous Year Questions

10 GATE previous year questions on Single phase transformer: equivalent circuit, phasor diagram, open circuit and short circuit tests, regulation and efficiency (Electrical Machines, Electrical Engineering) with answers and explanations, from every paper.

  1. GATE 2015 EE Q32 (1 mark, Multiple choice) – The self inductance of the primary winding of a single phase, 50 Hz, transformer is 800 mH, and that of the secondary winding is 600 mH. The mutual…
  2. GATE 2016 EE Q35 (1 mark, Multiple choice) – If an ideal transformer has an inductive load element at port 2 as shown in the figure below, the equivalent inductance at port 1 is
  3. GATE 2018 EE Q11 (1 mark, Multiple choice) – A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its series impedance at full load. Of this, 3% is due to…
  4. GATE 2019 EE Q18 (1 mark, Multiple choice) – A 5 kVA, 50 V/100 V, single-phase transformer has a secondary terminal voltage of 95 V when loaded. The regulation of the transformer is
  5. GATE 2019 EE Q55 (2 marks, Numerical answer) – A single-phase transformer of rating 25 kVA, supplies a 12 kW load at power factor of 0.6 lagging. The additional load at unity power factor in kW…
  6. GATE 2020 EE Q31 (1 mark, Numerical answer) – A single-phase, 4 kVA, 200 V/100 V, 50 Hz transformer with laminated CRGO steel core has rated no-load loss of 450 W. When the high-voltage winding is…
  7. GATE 2021 EE Q43 (2 marks, Multiple choice) – In a single-phase transformer, the total iron loss is 2500 W at nominal voltage of 440 V and frequency 50 Hz. The total iron loss is 850 W at 220 V…
  8. GATE 2023 EE Q53 (2 marks, Numerical answer) – When the winding c-d of the single-phase, 50 Hz, two winding transformer is supplied from an AC current source of frequency 50 Hz, the rated voltage…
  9. GATE 2024 EE Q18 (1 mark, Multiple choice) – Which one of the following options represents possible voltage polarities in a single phase two winding transformer? Here, V p is the applied primary…
  10. GATE 2026 EE Q31 (1 mark, Multiple select) – A 220 V/12 V single-phase transformer is designed for use in India and rated 100 VA at 50 Hz. Later, this unit is shipped to the USA where it is used…