Transformers Questions and Answers – Transformer Construction (Winding)

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This set of Transformers Multiple Choice Questions & Answers (MCQs) focuses on “Transformer Construction (Winding)”.

1. In the transformer which of the following winding has got more cross-sectional area?
a) Copper winding
b) Steel winding
c) Aluminium winding
d) Iron winding

Explanation: The wire used for carrying current in a transformer winding is either copper or aluminium. While aluminium wire is lighter and less expensive than copper wire, a larger cross-sectional area of conductor must be used to carry the same amount of current as with copper.

2. Primary winding of a transformer ______________
a) Is always a high voltage winding
b) Is always a low voltage winding
c) Could either be a low voltage or high voltage winding
d) Cannot be determined

Explanation: Primary winding used in a transformer, can be at higher or lower voltage potential, depending on the number of turns with secondary winding. For step up and step-down transformers primary winding will be at lower and higher potential respectively.

3. Which winding has more number of turns?
a) Low voltage winding
b) High voltage winding
c) Primary winding
d) Secondary winding

Explanation: High voltage winding always has a large number of turns, as voltage is directly proportional to the number of turns. If large numbered winding is present on primary side then the transformer is step down transformer.
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4. Part of the transformer which undergoes most damage from overheating is ___________
a) Iron core
b) Copper winding
c) Winding insulation
d) Frame or case

Explanation: Copper windings carry current through them. The heat loss producing in any winding carrying current is proportional to the square of the current passing through it multiplied with resistance. For large transformers, current is very high, so heating causes most of the damage to insulation material.

5. If a transformer is continuously operated the maximum temperature rise will occur in ___________
a) Core
b) Windings
c) Tank
d) Cannot be determined

Explanation: Copper windings carry currents in a transformer. The loss in form of heat in copper winding carrying current is proportional to the square of the current passing through them multiplied by the resistance of the winding. This loss is dissipated in heat and corresponding temperature rise.

6. If secondary number of turns are higher then, transformer is called _________
a) Step-down
b) Step-up
c) One-one
d) Autotransformer

Explanation: When secondary number of turns are higher compare to primary, voltage induced in secondary windings will obviously high. Thus, this transformer is used for stepping up the output voltage by keeping frequency constant.

7. If primary number of turns are higher then, transformer is called _________
a) Step-down
b) Step-up
c) One-one
d) Autotransformer

Explanation: When primary number of turns are higher compare to secondary, voltage induced in secondary windings will obviously low compare to primary. Thus, this transformer is used for stepping down the output voltage by keeping frequency constant.

8. If a transformer is having equal number of turns at primary and secondary then transformer is called as _______________
a) Step-down
b) Step-up
c) One-one
d) Autotransformer

Explanation: A transformer is having equal number of turns at primary and secondary then transformer is called as one-one transformer. This transformer have turns ratio equal to 1, so is the voltage ratio for the one-one transformer.

9. One to one transformers are used because ______________
a) To isolate any part of circuit electrically
b) To get more voltage at secondary
c) To get less voltage at secondary
d) To reduce losses, present in circuit

Explanation: In one to one transformers, we have same number of turns in primary and in secondary. So, increasing/ reducing voltage is not possible. They are generally used to isolate one part of circuit from another part of circuit, electrically.

10. Same type and kind of insulations are not used in all types of transformers.
a) True
b) False

Explanation: The windings of huge power transformers use conductors with heavier insulation and are assembled with greater mechanical support and the winding layers are insulated from each other, this is known as minor insulation for which pressed board or varnished cloth is used. While for major insulation and insulating cylinders, they are made of specially selected pressed board or synthetic resin bounded cylinders, is used between LV and core and LV and HV.

11. Sandwiched type of winding is used in ____________
a) In all transformers
b) In core type transformers
c) In shell type transformers
d) In all transformers except shell and core type transformers

Explanation: According to the construction of transformers core type transformers don’t require sandwiched wiring. While, in the shell type transformer, the primary and secondary windings pass inside the steel magnetic circuit (core) which forms a shell around the winding.

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