[amp_mcq option1=”lkV” option2=”33 kV” option3=”100 kV” option4=”330 kV” correct=”option3″]
Detailed SolutionThe dielectric strength of transformer oil is expected to be
Transformers
12. The use of higher flux density in the transformer design
[amp_mcq option1=”reduces weight per kVA” option2=”reduces iron losses” option3=”reduces copper losses” option4=”increases part load efficiency” correct=”option2″]
Detailed SolutionThe use of higher flux density in the transformer design
13. Sumpner’s test is conducted on transformers to determine
[amp_mcq option1=”temperature” option2=”stray losses” option3=”all-day efficiency” option4=”none of the above” correct=”option3″]
Detailed SolutionSumpner’s test is conducted on transformers to determine
14. Which motor is preferred for use in mines where explosive gases exist?
[amp_mcq option1=”Air motor” option2=”Induction motor” option3=”Shunt motor” option4=”Synchronous motor” correct=”option1″]
Detailed SolutionWhich motor is preferred for use in mines where explosive gases exist?
15. Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is
[amp_mcq option1=”approximately equal to one” option2=”less than one” option3=”great than one” option4=”none of the above” correct=”option1″]
16. The maximum efficiency of a distribution transformer is
[amp_mcq option1=”at no load” option2=”at 50% full load” option3=”at 80% full load” option4=”at full load” correct=”option1″]
Detailed SolutionThe maximum efficiency of a distribution transformer is
17. An ideal transformer has infinite values of primary and secondary inductances. The statement is
[amp_mcq option1=”TRUE” option2=”nan” option3=”nan” option4=”nan” correct=”option1″]
18. The path of a magnetic flux in a transformer should have
[amp_mcq option1=”high resistance” option2=”high reluctance” option3=”low resistance” option4=”low reluctance” correct=”option4″]
Detailed SolutionThe path of a magnetic flux in a transformer should have
19. For a transformer, operating at constant load current, maximum efficiency will occur at
[amp_mcq option1=”0.8 leading power factor” option2=”0.8 lagging power factor” option3=”zero power factor” option4=”unity power factor” correct=”option4″]
20. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
[amp_mcq option1=”less than 15 A” option2=”more than 15 A” option3=”15 A” option4=”none of the above” correct=”option2″]