Iron loss of a transformer can be measured by____________?

Star/star transformers work satisfactorily when________________?

A. load is unbalanced only
B. load is balanced only
C. on balanced as well as unbalanced loads
D. none of the above

For a transformer, operating at constant load current, maximum efficiency will occur at______________?

A. 0.8 leading power factor
B. 0.8 lagging power factor
C. zero power factor
D. unity power factor

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

Buchholz’s relay gives warning and protection against_________________?

A. electrical fault inside the transformer itself
B. electrical fault outside the transformer in outgoing feeder
C. for both outside and inside faults
D. none of the above

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

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

During short circuit test iron losses are negligible because of _____________?

A. the current on secondary side is negligible
B. the voltage on secondary side does not vary
C. the voltage applied on primary side is low
D. full-load current is not supplied to the transformer