151. When the transformer core is made of copper , which of the following loss will be more?
a. copper loss
b. hysteresis loss
c. thermal loss
d. eddy current loss
152. poreclain bushings on transformers are normally not used beyond
a. 11 kV
b. 66 kV
c. 132 kV
d. 220 kV
153. In scott connection the neutral point divides the windings of the teaser transformer in the ratio of
a. 1;1
b. 1:2
c. 1:3
d. 1:4
154. Which of the following test can be used to determine the efficiency of two identical transformer at full load
a. open-circuit test
b. short-circuit test
c. type tests
d. back to back test
155. The inductive reactance of a transformer depends on
a. electromotive force
b. magnetomotive force
c. magnetic flux
d. leakage flux
156. Which of the following prevents the damage to a transformer due to lightning and switching ?
a. Buchholz relay
b. Conservator
c. Breather
d. Hom gap
157. The voltage regulation of a transformer can be zero when the power factor is
a. unity
b. 0.5
c. leading
d. lagging
158. The harmonic current in transformer increase all of the following EXCEPT
a. copper loss
b. core loss
c. magnetic interference with protective relays
d. secondary voltage
159. The value of useful flux least depends on
a. magnetomotive force
b. voltage
c. load
d. all of the abovew
160. In which of the following transformer part of primary windings also serves as the secondary winding
a. step up transformer
b. current transformer
c. potential transformer
d. auto-transformer
