Reduction in core losses and increase in permeability are obtained with transformer employing__________?

A. core built-up of laminations of cold rolled grain oriented steel
B. core built-up of laminations of hot rolled sheet
C. either of the above
D. none of the above

In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?

A. to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
B. to absorb the line surge voltage and save the winding of transformer from damage
C. to reflect the line surge and save the winding of a transformer from damage
D. none of the above

N atural air coo ling is generally restricted for transformers up to__________?

A. 1.5 MVA
B. 5 MVA
C. 15 MVA
D. 50 MVA

A shell-type transformer has_________?

A. high eddy current losses
B. reduced magnetic leakage
C. negligibly hysteresis losses
D. none of the above

A transformer can have regulation closer to zero___________?

A. on full-load
B. on overload
C. on leading power factor
D. on zero power factor

The function of breather in a transformer is___________?

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

The secondary winding of which of the following transformers is always kept closed?

A. Step-up transformer
B. Step-down transformer
C. Potential transformer
D. Current transformer

The size of a transformer core will depend on__________?

A. frequency
B. area of the core
C. flux density of the core material
D. A. and B. both

Short circuit test on transformers is conducted to determine____________?

A. hysteresis losses
B. copper losses
C. core losses
D. eddy current losses

For the parallel operation of single phase transformers it is necessary that they should have___________?

A. same efficiency
B. same polarity
C. same kVA rating
D. same number of turns on the secondary side.