Transformer mcq objective questions and answers part3

Q1. The efficiencies of transformers compared with that of electric motors of the same power are
(A) the same
(B) much smaller
(C) much higher
(D) somewhat higher

Q2. Minimum voltage regulation occurs when the power factor of the load is
(A) unity
(B) lagging
(C) leading
(D) zero

Q3. The rating of transformer may be expressed in ____________.
(A) kW
(B) kVAR
(C) kVA
(D) Watt

Q4. Part of the transformer which is most subject to damage from overheating is
(A) iron core
(B) copper winding
(C) winding insulation
(D) frame or case

Q5. What will happen if the primary of a transformer is connected to D.C supply?
(A) Transformer will operate with low efficiency
(B) Transformer will operate with high efficiency
(C) Transformer may start to smoke and burn
(D) None of these

Q6. If a transformer is switched on to a voltage more than the rated voltage
(A) its power factor will decreases
(B) its power factor will increase
(C) its power factor will remain unaffected
(D) its power factor will be zero

Q7. The maximum load that a power transformer can carry is limited by
(A) rise in temperature
(B) dielectric strength of oil
(C) voltage ratio
(D) copper loss

Q8. The hum in a transformer is mainly due to
(A) load changes
(B) oil in the transformer
(C) magnetostriction
(D) mechanical vibrations

Q9. The noise produced by a transformer is
(A) zoom
(B) hum
(C) ringing
(D) buzz

Q10. Which of the following parts of a transformer is visible from outside ?
(A) Bushings
(B) Core
(C) Primary winding
(D) Secondary winding

Q11. For a transformer, operating at constant load current, maximum efficiency will occur at
(A) 0.7 leading power factor
(B) 0.7 lagging power factor
(C) zero power factor
(D) unity power factor

Q12. In a transformer the resistance between its primary and secondary should be
(A) zero
(B) 100
(C) 1000
(D) infinity

Q13. A Step Up transformer _____________
(A) Step down the level of current
(B) Step up level the power
(C) Step up the level of Frequency
(D) None of these

Q14. In a given transformer for a given applied voltage, the losses which remain constant irrespective of load changes are
(A) hysteresis and eddy current losses
(B) friction and winding losses
(C) copper losses
(D) none of the above

Q15. A shell-type transformer has
(A) high eddy current losses
(B) reduced magnetic leakage
(C) negligibly hysteresis losses
(D) none of the above

Q16. The size of a transformer core will depend on
(A) frequency
(B) area of the core
(C) Both of these
(D) None of these

Q17. 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) absorb moisture when outside air enters the transformer

Q18. Negative voltage regulation is indicative that the load is
(A) capacitive only
(B) inductive only
(C) inductive or resistive
(D) none of these

Q19. An ideal transformer is one which has
(A) no losses and magnetic leakage
(B) interleaved primary and secondary windings
(C) a common core for its primary and secondary windings
(D) None of these

Q20. Power transformers are generally designed to have maximum efficiency around
(A) no-load
(B) half-load
(C) near full-load
(D) 50% overload