Transformers MCQ Objectives

1. Which of the following 3-phase connection of a transformer causes interference with the neighboring communication lines:

a) Delta-star

b) Star-delta

c) Star-star

d) Delta-star 

C

2. Power transformers are provided with additional cooling arrangement in order to:

a) Increase the power rating

b) Increase insulation life

c) Lower operating temperature

d) All the above

D

3. A Distribution transformer is selected on the basis of:

a) Voltage regulation

b) Efficiency

c) All day efficiency

d) All the above

C

4. The winding used in 3-phase shell type transformer is __ type:

a) Circular

b) Cylindrical

c) Sandwitch

d) Rectangular

C

5. Five limb core construction is preferred over three limb construction as in this type of construction:

a) Hysteresis loss is reduced

b) Eddy current loss is reduced

c) Magnetic reluctance of the three phases can be balanced

d) Copper losses can be reduced

C

6. The most common method of cooling employed in power transformer is:

a) Oil natural

b) Natural cooling

c) Air cooling

d) Air-blast cooling

A

7. In large power transformer, best utilization of available core space can be made by employing __ cross section

a) Rectangular

b) Square

c) Stepped

d) None of the above

C

8. The distribution transformer is designed with minimum possible core losses. This is because:

a) The primary of the distribution transformer is energized for all 24 hours

b) Iron losses will cause undue heating

c) Iron losses may cause damage to the insulation

d) All the above

A

9. Which of the following transformer connection will give highest secondary voltage:

a) Delta primary, delta secondary

b) Delta primary, star secondary

c) Star primary, delta secondary

d) Star primary, star secondary

B

10. The chemical used in the breather is:

a) Sodium chloride

b) Silica sand

c) Silica gel

d) Copper silicate gel

C

11. Major insulation in a transformer is the insulation between the:

a) LV wining and core

b) LV winding and HV winding

c) Turns of the windings

d) Both (a) and (b)

D

12. Low voltage winding is placed next to the core in the case of concentric windings as __ is reduced:

a) Hysteresis loss

b) Leakage fluxes

c) Eddy current loss

d) Insulation requirement

D

13. The transformer oil should have:

a) High volatility

b) High viscosity

c) High dielectric strength

d) All the above

C

14. The Transformer core laminations are insulated from each other by:

a) Paper

b) Thin varnish coating

c) Mica strip

d) All the above can be used for insulation

B

15.  For minimum weight of the transformer, the iron weight should be __ the weight of the copper:

a) More than

b) Equal to

c) Less than

d) None of the above

B