Power Transformer MCQs Part 12

111. Ina transformer minimum voltage regulation occurs when the power factor of the load is
a. unity
b. 0.707
c. lagging
d. leading

112. Scott connection are used for
a. single phase to three phase transformation
b. three phase to single phase transformation
c.. three phase to three phase and three phase to 2 phase transformation
d.. any of the above

113. In scott connections the neutral point divide the teaser winding in the ratio
a. 1:3
b. 1:2
c. 1:1
d. 1:4

114. In a large capacity transformer 5% of the turns at the end of high voltage windings are provided with extra insulation to
a. provides protection against hightning
b. provide protection against corona
c. provide protection due to surges occuring during switching operations
d. for all above protections

115. The permitivity of bakelite is approximately
a. 1.0
b. 2.2
c. 4.4
d. 44

116. The permitivity of transformer oil is about
a. 1.0
b. 2.2
c. 22
d. 44

117. Buchholz relay is used in
a. lime protection
b. greator protection
c. transformer protection motor protection

118. Maximum regulation of a transformer occurs
a. rated KVA of transformer
b. unity power factor
c. lagging power factor
d. leading power factor

119. The power factor at which the regulation will be maximum is
a. 0.385 leading
b. 0.615 leading
c. 0.385 lagging
d. 0.615 lagging

120. The maximum regulation of this transformer will be
a. 0.5%
b. 2.5%
c. 4.5%
d. 6.5%