The hum in a transformer is mainly attributed to______________?

A. Load changes
B. Oil in the transformer
C. Magnetostriction
D. Mechanical vibrations

If a transformer is continuously operated the maximum temperature rise will occur in_______________?

A. Core
B. Windings
C. Tank
D. Any of the above

Which of the following loss in a transformer is zero even at full load ____________?

A. Core loss
B. Friction loss
C. Eddy current loss
D. Hysteresis loss

Helical coils can be used on___________________?

A. Low voltage side of high kva transformers
B. High frequency transformers
C. High voltage side of small capacity transformers
D. High voltage side of high kva rating transformers

Which of the following is not a routine test on transformers ?

A. Core insulation voltage test
B. Impedance test
C. Radio interference test
D. Polarity test

A transformer can have zero voltage regulation at______________?

A. Leading power factor
B. Lagging power factor
C. Unity power factor
D. Zero power factor

Noise level test in a transformer is a______________?

A. Special test
B. Routine test
C. Type test
D. None of the above

The path of the magnetic flux in transformer should have____________?

A. High reluctance
B. Low reactance
C. High resistance
D. Low resistance

Which of the following properties is not necessarily desirable for the material for transformer core ?

A. Low hysteresis loss
B. High permeability
C. High thermal conductivity
D. Adequate mechanical strength

The leakage flux in a transformer depends upon______________?

A. Load current
B. Load current and voltage
C. Load current, voltage and frequency
D. Load current, voltage, frequency and power factor