GETCO Exam Paper (30-11-2008)
The function of a breather in a transformer is

to arrest flow of moisture into the tank
to suppress harmonics
to provide protection against over currents
to control the level of oil in the tank

ANSWER EXPLANATION DOWNLOAD EXAMIANS APP

GETCO Exam Paper (30-11-2008)
In a transformer it is difficult to measure the efficiency by output-input measurement methods because

output is out of phase with respect to input
losses are abnormally high
the output is sinusoidal and hence cannot be measured
efficiency of transformer is usually high and hence extremely accurate measurements will be necessary

ANSWER DOWNLOAD EXAMIANS APP