Electrical Transformers Interview Questions and Answers - Set 11 - ObjectiveBooks

Electrical Transformers Interview Questions and Answers - Set 11

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

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