[amp_mcq option1=”to provide free passage to the cooling oil” option2=”to insulate the coils from each other” option3=”both (A) and (B)” option4=”none of the above” correct=”option3″]
Detailed SolutionSpacers are provided between adjacent coils
Transformers
42. During short circuit test iron losses are negligible because
[amp_mcq option1=”the current on secondary side is negligible” option2=”the voltage on secondary side does not vary” option3=”the voltage applied on primary side is low” option4=”full-load current is not supplied to the transformer” correct=”option4″]
Detailed SolutionDuring short circuit test iron losses are negligible because
43. Which of the following insulating materials can withstand the highest temperature safely?
[amp_mcq option1=”Cellulose” option2=”Asbestos” option3=”Mica” option4=”Glass fibre” correct=”option4″]
44. If the supply frequency to the transformer is increased, the iron loss will
[amp_mcq option1=”not change” option2=”decrease” option3=”increase” option4=”any of the above” correct=”option3″]
Detailed SolutionIf the supply frequency to the transformer is increased, the iron loss will
45. In a power or distribution transformer about 10 per cent end turns are heavily insulated
[amp_mcq option1=”to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns” option2=”to absorb the line surge voltage and save the winding of transformer from damage” option3=”to reflect the line surge and save the winding of a transformer from damage” option4=”none of the above” correct=”option1″]
46. Iron loss of a transformer can be measured by
[amp_mcq option1=”low power factor wattmeter” option2=”unity power factor wattmeter” option3=”frequency meter” option4=”any type of wattmeter” correct=”option1″]
Detailed SolutionIron loss of a transformer can be measured by
47. Negative voltage regulation is indicative that the load is
[amp_mcq option1=”capacitive only” option2=”inductive only” option3=”inductive or resistive” option4=”none of the above” correct=”option1″]
Detailed SolutionNegative voltage regulation is indicative that the load is
48. Losses which occur in rotating electric machines and do not occur in trans formers are
[amp_mcq option1=”friction and windage losses” option2=”magnetic losses” option3=”hysteresis and eddy current losses” option4=”copper losses” correct=”option1″]
49. The no load current in a transformer lags behind the applied voltage by an angle of about
[amp_mcq option1=”180°” option2=”120°” option3=”90°” option4=”75°” correct=”option3″]
50. During open circuit test of a transformer
[amp_mcq option1=”primary is supplied rated voltage” option2=”primary is supplied full-load current” option3=”primary is supplied current at reduced voltage” option4=”primary is supplied rated kVA” correct=”option1″]