1. In a transformer
a) both oc and sc tests are conducted on lv side.
b) oc test is conducted on hv and sc test is conduted on lv.
c) oc test is conducted on lv and sc test is conducted on hv.
d) both oc and sc test are conducted on hv side.
ans. c
2. For successful parallel operation of two single phase transformers, the essential condition is that their
a) percentage impedances should be equal
b) turns ratios should be exactly equal
c) polarities must be properly connected
d) KVA ratings should be equal.
ans. c
3. In a single phase induction regulator, the output voltage can be varied
a) both in magnitude and phase
b) in magnitude only
c) in phase only
d) in magnitude less than the supply voltage
ans. b
4. Transformer action requires a
a) constant magnetic flux
b) increasing magnetic flux
c) pulsating magnetic flux
d) alternating electric flux
ans. c
5. In an oil filled transformer, oil is provided for
a) cooling
b) insulation
c) lubrication
d) both cooling and insulation
ans. d
6. Transformer cores are laminated to reduce
a) eddy current loss
b) hysteresis loss
c) both a and b
d) ohmic loss
ans. a
7. CRGO laminations in a transformer are used to minimise
a) eddy current loss
b) hysteresis loss
c) both a and b
d) ohmic loss
ans. b
8. An Air-core transformer, as compared to iron core transformer, has
a) less magnetic core loss
b) more magnetic core loss
c) no magnetic core loss
d) less ohmic loss
ans. c
9. Transformer zero voltage regulation occurs at
a) unity pf
b) leading pf
c) lagging pf
d) zero pf leading
ans. b
10. Transformer maximum efficiency, for a constant load current, occurs at
a) 0.8 pf
b) zero pf leading
c) zero pf lagging
d) unity power factor
ans. d
a) both oc and sc tests are conducted on lv side.
b) oc test is conducted on hv and sc test is conduted on lv.
c) oc test is conducted on lv and sc test is conducted on hv.
d) both oc and sc test are conducted on hv side.
ans. c
2. For successful parallel operation of two single phase transformers, the essential condition is that their
a) percentage impedances should be equal
b) turns ratios should be exactly equal
c) polarities must be properly connected
d) KVA ratings should be equal.
ans. c
3. In a single phase induction regulator, the output voltage can be varied
a) both in magnitude and phase
b) in magnitude only
c) in phase only
d) in magnitude less than the supply voltage
ans. b
4. Transformer action requires a
a) constant magnetic flux
b) increasing magnetic flux
c) pulsating magnetic flux
d) alternating electric flux
ans. c
5. In an oil filled transformer, oil is provided for
a) cooling
b) insulation
c) lubrication
d) both cooling and insulation
ans. d
6. Transformer cores are laminated to reduce
a) eddy current loss
b) hysteresis loss
c) both a and b
d) ohmic loss
ans. a
7. CRGO laminations in a transformer are used to minimise
a) eddy current loss
b) hysteresis loss
c) both a and b
d) ohmic loss
ans. b
8. An Air-core transformer, as compared to iron core transformer, has
a) less magnetic core loss
b) more magnetic core loss
c) no magnetic core loss
d) less ohmic loss
ans. c
9. Transformer zero voltage regulation occurs at
a) unity pf
b) leading pf
c) lagging pf
d) zero pf leading
ans. b
10. Transformer maximum efficiency, for a constant load current, occurs at
a) 0.8 pf
b) zero pf leading
c) zero pf lagging
d) unity power factor
ans. d
