Practice Test: Question Set - 13
1. When a given transformer is run at its rated voltage but reduced frequency, its
- (A) Flux density remains unaffected
- (B) Iron losses are reduced
- (C) Core flux density is reduced
- (D) Core flux density is increased
2. A transformer can have regulation closer to zero
- (A) On full-load
- (B) On overload
- (C) On leading power factor
- (D) On zero power factor
3. The path of a magnetic flux in a transformer should have
- (A) High resistance
- (B) High reluctance
- (C) Low resistance
- (D) Low reluctance
4. The no load current in a transformer lags behind the applied voltage by an angle of about
- (A) 180°
- (B) 120°
- (C) 90°
- (D) 75°
5. The thickness of laminations used in a transformer is usually
- (A) 0.4 mm to 0.5 mm
- (B) 4 mm to 5 mm
- (C) 14 mm to 15 mm
- (D) 25 mm to 40 mm
6. The leakage flux in a transformer depends upon
- (A) Load current
- (B) Load current and voltage
- (C) Load current, voltage and frequency
- (D) Load current, voltage, frequency and power
factor
7. Which winding of the transformer has less cross-sectional area?
- (A) Primary winding
- (B) Secondary winding
- (C) Low voltage winding
- (D) High voltage winding
8. The secondary winding of which of the following transformers is always kept closed?
- (A) Step-up transformer
- (B) Step-down transformer
- (C) Potential transformer
- (D) Current transformer
9. Which of the following is the most likely source of harmonics in a transformer?
- (A) Poor insulation
- (B) Overload
- (C) Loose connections
- (D) Core saturation
10. In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are
- (A) Hysteresis and eddy current losses
- (B) Friction and windage losses
- (C) Copper losses
- (D) None of the above
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