1. Winding to earth faults may be caused by
a) sludging of the oil
b) surge voltage only
c) current chopping only
d) both surge voltages and current chopping
ans. d
2. The two windings of a transformer are designated as
a) primary and secondary windings
b) primary and hv windings
c) secondary and lv windings
d) hv and lv windings
ans. d
3. The flux involved in the emf equation of a transformer has
a) rms value
b) average value
c) total value
d) maximum value
ans. d
4. The leakage flux in a transformer depends upon
a) the applied voltage
b) the frequency
c) the load current
d) the mutual flux
ans. c
5. Good voltage regulation of a transformer means that the difference between its no-load voltage and full-load voltage is
a) very high
b) low
c) very low
d) none of these
ans. d
6. Distribution transformers have core losses
a) greater than copper losses
b) equal to copper losses
c) less than copper losses
d) equal to 1/2 (copper losses)
ans. c
7. Eddy current loss in a transformer depends on
a) both voltage and frequency
b) voltage alone
c) load current alone
d) thickness of core
ans. d
8. Hysteresis loss in a transformer depends upon
a) frequency
b) supply voltage
c) square of the frequency alone
d) square of the voltage alone
ans. a
9. The open-circuit test on transformer is conducted to obtain
a) the leakage impedances
b) the ohmic loss
c) hysteresis loss only
d) core losses
ans. d
10. The short-circuit test on a transformer is conducted to obtain
a) core losses at any load
b) ohmic losses at any load
c) hysteresis losses
d) both core and ohmic losses
ans. b
a) sludging of the oil
b) surge voltage only
c) current chopping only
d) both surge voltages and current chopping
ans. d
2. The two windings of a transformer are designated as
a) primary and secondary windings
b) primary and hv windings
c) secondary and lv windings
d) hv and lv windings
ans. d
3. The flux involved in the emf equation of a transformer has
a) rms value
b) average value
c) total value
d) maximum value
ans. d
4. The leakage flux in a transformer depends upon
a) the applied voltage
b) the frequency
c) the load current
d) the mutual flux
ans. c
5. Good voltage regulation of a transformer means that the difference between its no-load voltage and full-load voltage is
a) very high
b) low
c) very low
d) none of these
ans. d
6. Distribution transformers have core losses
a) greater than copper losses
b) equal to copper losses
c) less than copper losses
d) equal to 1/2 (copper losses)
ans. c
7. Eddy current loss in a transformer depends on
a) both voltage and frequency
b) voltage alone
c) load current alone
d) thickness of core
ans. d
8. Hysteresis loss in a transformer depends upon
a) frequency
b) supply voltage
c) square of the frequency alone
d) square of the voltage alone
ans. a
9. The open-circuit test on transformer is conducted to obtain
a) the leakage impedances
b) the ohmic loss
c) hysteresis loss only
d) core losses
ans. d
10. The short-circuit test on a transformer is conducted to obtain
a) core losses at any load
b) ohmic losses at any load
c) hysteresis losses
d) both core and ohmic losses
ans. b
