01․ Which of the following is not a part of transformer?
Commutator is a part of DC machine.
02․ Maximum allowable acidity level of power transformer insulating oil is generally taken as
As per IS 1866 of 2000 the maximum allowable acidity level of transformer oil is 0.3 mg of KOH / gm.
03․ Maximum allowable tan - delta (tanδ) of dielectric dispassion factor of power transformer insulating oil is generally taken as
As per IS 1866 of 2000 the maximum allowable tan - delta ( tanδ ) of dielectric dispassion factor of power transformer insulating oil is 1 at 90°C.
04․ Minimum allowable resistivity of power transformer insulating oil is generally taken as
As per IS 1866 of 2000 the minimum allowable resistivity of transformer oil is 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 Ω - cm at 90°C.
05․ Maximum allowable moisture content of power transformer insulating oil is generally taken as
As per IS 1866 of 2000 the maximum allowable moisture content of power transformer insulating oil is 35 ppm.
06․ What does the use the of height flux density value in transformer design lead to?
So for a constant voltage input φfT = constant. As T = constant and f = constant so φ = constant of BmA = Constant. So if Bm increases, area of cross section of core decreases. Hence weight/KVA decreases.
07․ Dissolve gas analysis of transformer oil is carried out to determine
Whenever there is any thermal fault occurs inside the transformer the oil gets decomposed and produces different gases which are dissolved in transformer insulating oil. By quantitative analyzing these dissolved gases one can predict nature of internal fault of transformer and also the internal condition of transformer.
08․ Fufuraldehyde analysis is done to determine the
When oil soaked paper insulation in transformer is damaged by heat, some unique oil soluble compounds are realized and dissolved in the oil. These compounds belong to the Furfuraldehyde group. Hence, Fufuraldehyde analysis is done to determine the condition of paper insulation.
09․ Which of the following voltage regulator is preferred for providing large values of load current?
Under construction.
10․ In dc machines, the armature windings are placed on the rotor because of the necessity for
Required output from a DC machine is DC which can be collected from the armature. So armature should be placed on the rotor so that commutation action (ac to dc or dc to ac) take place.
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