[amp_mcq option1=”pulling the motor directly on line without a starter” option2=”locking of rotor due to harmonics” option3=”starting the motor on load which is more than the rated load” option4=”interchanging two supply phases for quick stopping” correct=”option4″]
Detailed SolutionIn case of 3-phase induction motors, plugging means
[amp_mcq option1=”To provide coupling between primary and secondary” option2=”To increase the magnitude of mutual flux” option3=”To decrease the magnitude of magnetizing current” option4=”To provide all above features” correct=”option4″]
Detailed SolutionThe purpose of providing iron core in a step-up transformer is
[amp_mcq option1=”asbestos fiber” option2=”silica sand” option3=”sodium chloride” option4=”silica gel” correct=”option4″]
[amp_mcq option1=”zoom” option2=”hum” option3=”ringing” option4=”buzz” correct=”option1″]
Detailed SolutionThe noise produced by a transformer is termed as
[amp_mcq option1=”0.2 to 0.5 per cent” option2=”2 to 5 per cent” option3=”12 to 15 per cent” option4=”20 to 30 per cent” correct=”option2″]
[amp_mcq option1=”0.2 lagging” option2=”0.2 leading” option3=”0.5 leading” option4=”unity” correct=”option1″]
Detailed SolutionThe power factor of an induction motor under no-load conditions will be closer to
[amp_mcq option1=”Ns” option2=”s.Ns” option3=”(1 – s)Ns” option4=”(Ns – 1)s” correct=”option3″]
[amp_mcq option1=”core” option2=”windings” option3=”tank” option4=”any of the above” correct=”option2″]
[amp_mcq option1=”ionizing air” option2=”absorbing moisture” option3=”cleansing the transformer oil” option4=”cooling the transformer oil” correct=”option2″]
Detailed SolutionThe chemical used in breather for transformer should have the quality of
[amp_mcq option1=”electrical fault inside the transformer itself” option2=”electrical fault outside the transformer in outgoing feeder” option3=”for both outside and inside faults” option4=”none of the above” correct=”option1″]
Detailed SolutionBuchholz’s relay gives warning and protection against