[amp_mcq option1=”mica strip” option2=”thin coat of varnish” option3=”paper” option4=”any of the above” correct=”option4″]
Detailed SolutionThe transformer laminations are insulated from each other by
Transformers
12. No-load current of a transformer has
[amp_mcq option1=”has high magnitude and low power factor” option2=”has high magnitude and high power factor” option3=”has small magnitude and high power factor” option4=”has small magnitude and low power factor” correct=”option3″]
13. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
[amp_mcq option1=”friction and windage losses” option2=”copper losses” option3=”hysteresis and eddy current losses” option4=”none of the above” correct=”option2″]
14. Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
[amp_mcq option1=”short-circuiting of the secondaries” option2=”power factor of one of the transformers is leading while that of the other lagging” option3=”transformers having higher copper losses will have negligible core losses” option4=”loading of the transformers not in proportion to their kVA ratings” correct=”option4″]
15. Which of the following acts as a protection against high voltage surges due to lightning and switching?
[amp_mcq option1=”Horn gaps” option2=”Thermal overload relays” option3=”Breather” option4=”Conservator” correct=”option1″]
16. In a transformer the resistance between its primary and secondary is
[amp_mcq option1=”zero” option2=”1 ohm” option3=”1000 ohms” option4=”infinite” correct=”option4″]
Detailed SolutionIn a transformer the resistance between its primary and secondary is
17. Which of the following parts of a transformer is visible from outside?
[amp_mcq option1=”Bushings” option2=”Core” option3=”Primary winding” option4=”Secondary winding” correct=”option1″]
Detailed SolutionWhich of the following parts of a transformer is visible from outside?
18. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
[amp_mcq option1=”50°C” option2=”80°C” option3=”100°C” option4=”150°C” correct=”option4″]
19. Primary winding of a transformer
[amp_mcq option1=”is always a low voltage winding” option2=”is always a high voltage winding” option3=”could either be a low voltage or high voltage winding” option4=”none of the above” correct=”option3″]
20. The core used in high frequency transformer is usually
[amp_mcq option1=”copper core” option2=”cost iron core” option3=”air core” option4=”mild steel core” correct=”option3″]
Detailed SolutionThe core used in high frequency transformer is usually