Practice Test: Question Set - 11
1. The function of breather in a transformer is
- (A) To provide oxygen inside the tank
- (B) To cool the coils during reduced load
- (C) To cool the transformer oil
- (D) To arrest flow of moisture when outside air
enters the transformer
2. Losses which occur in rotating electric machines and do not occur in transformers are
- (A) Friction and windage losses
- (B) Magnetic losses
- (C) Hysteresis and eddy current losses
- (D) Copper losses
3. Which of the following parts of a transformer is visible from outside?
- (A) Bushings
- (B) Core
- (C) Primary winding
- (D) Secondary winding
4. The efficiency of a transformer, under heavy loads, is comparatively low because
- (A) Copper loss becomes high in proportion to
the output
- (B) Iron loss is increased considerably
- (C) Voltage drop both in primary and secondary
becomes large
- (D) Secondary output is much less as compared to
primary input
5. Autotransformer makes effective saving on copper and copper losses, when its transformation ratio is
- (A) Approximately equal to one
- (B) Less than one
- (C) Greater than one
- (D) None of the above
6. A transformer core is laminated to
- (A) Reduce hysteresis loss
- (B) Reduce eddy current losses
- (C) Reduce copper losses
- (D) Reduce all above losses
7. No-load current in a transformer
- (A) Lags behind the voltage by about 75°
- (B) Leads the voltage by about 75°
- (C) Lags behind the voltage by about 15°
- (D) Leads the voltage by about 15°
8. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
- (A) Friction and windage losses
- (B) Copper losses
- (C) Hysteresis and eddy current losses
- (D) None of the above
9. Two transformers operating in parallel will share the load depending upon their
- (A) Leakage reactance
- (B) Per unit impedance
- (C) Efficiencies
- (D) Ratings
10. In a transformer the resistance between its primary and secondary is
- (A) Zero
- (B) 1 ohm
- (C) 1000 ohms
- (D) Infinite
Blogger Comment
Facebook Comment