Top 80+ Solved Transformers MCQ Questions Answer
Q. N atural air coo ling is generally restricted for transformers up to
a. 1.5 MVA
b. 5 MVA
c. 15 MVA
d. 50 MVA
Q. A shell-type transformer has
a. high eddy current losses
b. reduced magnetic leakage
c. negligibly hysteresis losses
d. none of the above
Q. 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
Q. Which of the following is not the standard voltage for power supply in India ?
a. llkV
b. 33kV
c. 66 kV
d. 122 kV
Q. Reduction in core losses and increase in permeability are obtained with transformeremploying
a. core built-up of laminations of cold rolled grain oriented steel
b. core built-up of laminations of hot rolled sheet
c. either of the above
d. none of the above
Q. In a power or distribution transformer about 10 per cent end turns are heavily insulated
a. to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
b. to absorb the line surge voltage and save the winding of transformer from damage
c. to reflect the line surge and save the winding of a transformer from damage
d. none of the above
Q. For given applied voltage, with the increase in frequency of the applied voltage
a. eddy current loss will decrease
b. eddy current loss will increase
c. eddy current loss will remain unchanged
d. none of the above
Q. Losses which occur in rotating electric machines and do not occur in trans formersare
a. friction and windage losses
b. magnetic losses
c. hysteresis and eddy current losses
d. copper losses
Q. In a given transformer for a given applied voltage, losses which remain constantirrespective of load changes are
a. hysteresis and eddy current losses
b. friction and windage losses
c. copper losses
d. none of the above
Q. Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect ?
a. Its secondary current is 5 A
b. Its secondary voltage is 400 V
c. Its rating is 2 kVA
d. Its secondary current is 20 A
Q. The secondary of a current transformer is always short-circuited under operatingconditions because it
a. avoids core saturation and high voltage induction
b. is safe to human beings
c. protects the primary circuit
d. none of the above
Q. In a transformer the resistance between its primary and secondary should be
a. zero
b. 10 Q
c. 1000 Q
d. infinity
Q. A good voltage regulation of a transformer means
a. output voltage fluctuation from no load to full load is least
b. output voltage fluctuation with power factor is least
c. difference between primary and secondary voltage is least
d. difference between primary and secondary voltage is maximum
Q. For a transformer, operating at constant load current, maximum efficiency will occur at
a. 0.8 leading power factor
b. 0.8 lagging power factor
c. zero power factor
d. unity power factor