1. While conducting short-circuit test on a transformer the following side is short-circuited
a) HV side
b) LV side
c) Primary side
d) none of these
ans. b
2. The secondary of a current transformer is always short circuited under operating conditions because
a) it protects the primary circuits
b) it is safer to human beings
c) it avoids core saturation and high voltage induction
d) none of these
ans. c
3. Two transformers operating in parallel will share the load depending upon their
a) ratings
b) leakage reactance
c) efficiency
d) p.u. impedance
ans. a
4. Iron losses of a transformer can be calculated by knowing the weights of
a) cores only
b) yokes only
c) copper winding only
d) cores and yokes
ans. d
5. With the increase in supply frequency of a transformer there is
a) decrease in rating
b) increase in rating
c) no change in rating
d) none of these
ans. b
6. Silicon steel is preferred for transformer core because
a) it decrease the permeability of the core
b) it reduces both eddy current loss and hysteresis loss
c) it reduces resistivity of the core
d) it decreases the tensile strength
ans. b
7. The magnetic properties of silicon steel crystal are best
a) along the cube edges
b) along the surface diagonals
c) along the cubic diagonals
d) none of the above
ans. a
8. The magnetic properties of cold rolled grain oriented silicon steel are excellent
a) against the direction of rolling
b) at the right angles to the direction of rolling
c) along the direction of rolling
d) none of these
ans. c
9. For large power transformer the best utilisation of available core space can be made by using
a) rectangular core section
b) square core section
c) stepped core section
d) none of the these
ans. c
10. Five limb core construction has an advantage over the three limb core construction that
a) the eddy current loss is less
b) the magnetic reluctance of the three phases can be balanced
c) the hysteresis loss is less
d) the permeability is higher
ans. b
a) HV side
b) LV side
c) Primary side
d) none of these
ans. b
2. The secondary of a current transformer is always short circuited under operating conditions because
a) it protects the primary circuits
b) it is safer to human beings
c) it avoids core saturation and high voltage induction
d) none of these
ans. c
3. Two transformers operating in parallel will share the load depending upon their
a) ratings
b) leakage reactance
c) efficiency
d) p.u. impedance
ans. a
4. Iron losses of a transformer can be calculated by knowing the weights of
a) cores only
b) yokes only
c) copper winding only
d) cores and yokes
ans. d
5. With the increase in supply frequency of a transformer there is
a) decrease in rating
b) increase in rating
c) no change in rating
d) none of these
ans. b
6. Silicon steel is preferred for transformer core because
a) it decrease the permeability of the core
b) it reduces both eddy current loss and hysteresis loss
c) it reduces resistivity of the core
d) it decreases the tensile strength
ans. b
7. The magnetic properties of silicon steel crystal are best
a) along the cube edges
b) along the surface diagonals
c) along the cubic diagonals
d) none of the above
ans. a
8. The magnetic properties of cold rolled grain oriented silicon steel are excellent
a) against the direction of rolling
b) at the right angles to the direction of rolling
c) along the direction of rolling
d) none of these
ans. c
9. For large power transformer the best utilisation of available core space can be made by using
a) rectangular core section
b) square core section
c) stepped core section
d) none of the these
ans. c
10. Five limb core construction has an advantage over the three limb core construction that
a) the eddy current loss is less
b) the magnetic reluctance of the three phases can be balanced
c) the hysteresis loss is less
d) the permeability is higher
ans. b
