A. frequency
B. area of the core
C. flux density of the core material
D. A. and B. both
0
The secondary winding of which of the following transformers is always kept closed?
0
The function of breather in a transformer is___________?
A. Step-up transformer
B. Step-down transformer
C. Potential transformer
D. Current transformer
0
The efficiencies of transformers compared with that of electric motors of the same power are____________?
A. to provide oxygen inside the tank
B. to cool the coils during reduced load
C. to cool the transformer oil
D. to arrest flow of moisture when outside air enters the transformer
0
The transformer oil should have _______ volatility and _______ viscosity?
A. about the same
B. much smaller
C. much higher
D. somewhat smaller
E. none of the above
0
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of_________________?
A. low,low
B. high,high
C. low,high
D. high,low
0
For the parallel operation of single phase transformers it is necessary that they should have___________?
A. less than 15 A
B. more than 15 A
C. 15 A
D. none of the above
0
Minimum voltage regulation occurs when the power factor of the load is_____________?
A. same efficiency
B. same polarity
C. same kVA rating
D. same number of turns on the secondary side.
0
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is_________________?
A. unity
B. lagging
C. leading
D. zero
0
Short circuit test on transformers is conducted to determine____________?
A. approximately equal to one
B. less than one
C. great than one
D. none of the above
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