Transformers Online Test – Multiple Choice Questions and Answers 1. Transformer humming sound is reduced by the Proper design Proper bracing of transformers assemblies Proper insulation Proper design of winding 2. If 110 per cent of normal voltage and 110 per cent of normal frequency is applied to a transformer, the percentage change of eddy current losses will be 10% 20% 21% 25% 3. The thickness of a 50 Hz transformer lamination is 0.30 cm 0.33 m 0.35 mm 0.35 cm 4. If 90 per cent of normal voltage and 90 per cent of normal frequency are applied to a transformer, the per cent charge in hysteresis losses will be 4.7% 19% 20% 21% 5. The voltage regulation of a transformer at full-load 0.8 power factor lag is 6 per cent. Its voltage regulation at full-load 0.8 power factor lead will be 54% Zero Positive Negative 6. Transfer of electrical power from primary to secondary in a transformer takes place Electromagnetically Electrically Magnetically None of these 7. Oil in transformer is used to Cool the windings Transfer electrical energy Insulate the windings None of the above 8. The full-load efficiency of a transformer at 0.85 p.f. lag is 97 per cent. Its efficiency at full load 0.85 bpower factor lead will be 96% 97% 98% 99% 9. A power transformer is a constant Voltage device Current device Power device Main flux device 10. The required thickness of lamination in a transformer decreases when The applied frequency decreases The applied voltage increases The applied frequency increases The applied voltage decreases Loading … Question 1 of 10
