Electrical Transformer Construction: A Comprehensive Guide for Electrical Technology Students

Question 1

Which winding arrangement alternates layers of primary and secondary windings to increase coupling and reduce leakage flux?

Accepted Answer

Interleaved winding

Answer

Concentric winding

Answer

Layer winding

Answer

Pancake winding

Question 2

In an electrical transformer, what is the core's main purpose?

Accepted Answer

Conduct magnetic flux

Answer

Provide electrical insulation

Answer

Connect the windings electrically

Answer

Dissipate heat produced by the transformer

Question 3

What is the primary purpose of insulation resistance testing during transformer maintenance?

Accepted Answer

Evaluate the insulation's ability to withstand voltage stresses

Answer

Determine the resistance of the transformer windings

Answer

Identify winding shorts or open circuits

Answer

Establish the transformer's load capacity

Question 4

Which material is most commonly used for transformer cores due to its high permeability and low hysteresis loss?

Accepted Answer

Iron

Answer

Copper

Answer

Aluminum

Answer

Steel

Question 5

Which insulating material is typically used to separate the primary and secondary windings in a transformer to prevent electrical breakdown?

Accepted Answer

Paper

Answer

Oil

Answer

Resin

Answer

Rubber

Question 6

How is the voltage ratio between the primary and secondary windings of a transformer primarily determined?

Accepted Answer

By the ratio of the number of turns on each winding

Answer

By the core material used

Answer

By the thickness of the insulation between windings

Answer

By the physical size of the transformer

Question 7

Which type of transformer is primarily used to protect circuits from overvoltage conditions?

Accepted Answer

Isolation transformer

Answer

Step-up transformer

Answer

Step-down transformer

Answer

Autotransformer

Question 8

What is the primary purpose of cooling fins on transformers?

Accepted Answer

To increase the surface area for heat dissipation

Answer

To reduce noise levels produced by the transformer

Answer

To provide mechanical support for the transformer

Answer

To protect the transformer from lightning strikes

Question 9

Which safety precaution is most important to follow when working with transformers to prevent electrical shock?

Accepted Answer

Wear insulated rubber gloves

Answer

Use a voltmeter to test for voltage before touching

Answer

Keep transformers away from water or moisture

Answer

Clearly label all terminals on the transformer

Question 10

What is the main function of an autotransformer?

Accepted Answer

To change voltage levels while sharing a winding between the primary and secondary circuits

Answer

To provide electrical isolation between circuits

Answer

To stabilize voltage fluctuations

Answer

To protect against overcurrent conditions

Question 11

In the construction of electrical transformers, which material is typically used for the core?

Accepted Answer

Iron

Answer

Copper

Answer

Aluminum

Answer

Nickel

Question 12

Which component of a transformer provides electrical insulation between the core and the windings?

Accepted Answer

Insulation

Answer

Coil

Answer

Laminations

Answer

Yoke

Question 13

What is the ratio known as that represents the number of turns in the primary winding to the number of turns in the secondary winding?

Accepted Answer

Turns ratio

Answer

Voltage ratio

Answer

Current ratio

Answer

Power ratio

Question 14

Which type of transformer is commonly used to distribute electrical power in residential areas?

Accepted Answer

Distribution transformer

Answer

Power transformer

Answer

Instrument transformer

Answer

Autotransformer

Question 15

The primary purpose of the yoke in a transformer is to:

Accepted Answer

Provide a closed path for magnetic flux

Answer

Carry the transformer windings

Answer

Provide electrical insulation

Answer

Dissipate excessive heat

Question 16

A transformer that increases the voltage level is known as a:

Accepted Answer

Step-up transformer

Answer

Step-down transformer

Answer

Isolation transformer

Answer

Autotransformer

Question 17

Which test is specifically designed to check the insulation integrity of a transformer winding?

Accepted Answer

Megger test

Answer

Hi-pot test

Answer

Continuity test

Answer

Surge test

Question 18

How does the configuration of transformer windings impact its performance?

Accepted Answer

It influences both voltage regulation and efficiency.

Answer

It solely determines voltage regulation.

Answer

It solely determines efficiency.

Answer

It has no effect on transformer performance.

Question 19

The core of a transformer primarily serves the purpose of:

Accepted Answer

Providing a path for magnetic flux

Answer

Insulating the windings

Answer

Conducting electricity

Answer

Storing electrical energy

Question 20

Which winding is directly connected to the electrical power source?

Accepted Answer

Primary winding

Answer

Secondary winding

Answer

Tertiary winding

Answer

Interwinding

Question 21

The most common type of insulation material used in transformers is:

Accepted Answer

Paper

Answer

Metal

Answer

Rubber

Answer

Plastic

Question 22

Laminating the transformer core helps to:

Accepted Answer

Reduce eddy currents

Answer

Improve cooling efficiency

Answer

Increase magnetic flux

Answer

Insulate the windings

Question 23

Which type of transformer is specifically designed to prevent electrical shock by isolating circuits?

Accepted Answer

Isolation transformer

Answer

Step-up transformer

Answer

Step-down transformer

Answer

Autotransformer

Question 24

The ratio of the number of turns in the secondary winding to the number of turns in the primary winding of a transformer is known as the:

Accepted Answer

Turns ratio

Answer

Voltage ratio

Answer

Current ratio

Answer

Power ratio

Question 25

The purpose of a tap changer in a transformer is to:

Accepted Answer

Adjust the turns ratio to regulate voltage

Answer

Protect the transformer from overloads

Answer

Regulate current flow

Answer

Isolate the transformer from the circuit

Question 26

What are the key functions of the transformer tank in ensuring the transformer's reliability and longevity?

Accepted Answer

Protects against moisture and dust

Accepted Answer

Regulates temperature

Accepted Answer

Provides structural support

Question 27

In transformer construction, which core material is commonly used because of its advantageous magnetic properties?

Accepted Answer

Silicon steel

Answer

Copper

Answer

Aluminum

Answer

Plastic

Question 28

The core of a transformer is typically made of:

Accepted Answer

Laminated steel sheets

Answer

Solid copper

Answer

Plastic

Answer

Aluminum

Question 29

Laminating the core of a transformer reduces:

Accepted Answer

Eddy currents

Answer

Magnetic flux

Answer

Copper losses

Answer

Hysteresis losses

Question 30

In a transformer, the primary winding has:

Accepted Answer

High voltage and low current

Answer

High current and low voltage

Answer

Low voltage and high current

Answer

Same voltage and current as the secondary winding

Question 31

The insulation between the windings of a transformer prevents:

Accepted Answer

Electrical shorts

Answer

Noise

Answer

Overheating

Answer

Magnetic flux leakage

Question 32

A transformer with a single winding that serves as both the primary and secondary winding is called a:

Accepted Answer

Autotransformer

Answer

Power transformer

Answer

Distribution transformer

Answer

Isolation transformer

Question 33

The function of a step-down transformer is to:

Accepted Answer

Reduce voltage and increase current

Answer

Regulate voltage

Answer

Increase voltage and decrease current

Answer

Isolate circuits

Question 34

The purpose of a cooling system in a transformer is to:

Accepted Answer

Dissipate heat generated by losses

Answer

Reduce noise

Answer

Increase efficiency

Answer

Improve insulation

Question 35

Transformers used in power distribution systems are called:

Accepted Answer

Distribution transformers

Answer

Autotransformers

Answer

Power transformers

Answer

Isolation transformers

Question 36

What is the primary advantage of laminating the core of a transformer?

Accepted Answer

Reduces eddy current losses

Answer

Enhances efficiency

Answer

Improves insulation

Answer

Increases voltage handling capacity

Question 37

To ensure safety when working with transformers, the most crucial precaution is to:

Accepted Answer

Wear protective gloves

Answer

Check the transformer voltage with a voltmeter

Answer

Connect the transformer to a power source

Answer

Leave the transformer energized

Question 38

Which material is commonly employed in the construction of transformer cores?

Accepted Answer

Laminated silicon steel

Answer

Soft iron

Answer

Copper

Answer

Aluminum

Question 39

Why is laminated silicon steel employed in transformer cores?

Accepted Answer

To minimize eddy current losses

Answer

To enhance heat dissipation

Answer

To increase mechanical strength

Answer

To maximize magnetic flux density

Question 40

Which of the following factors does NOT influence the efficiency of an electrical transformer?

Accepted Answer

Load factor

Answer

Core losses

Answer

Winding losses

Question 41

Which material, with low hysteresis loss and high permeability, is commonly used to construct electrical transformer cores?

Accepted Answer

Crystalline silicon steel

Answer

Iron

Answer

Copper

Answer

Aluminum

Question 42

Why are the core laminations in a transformer interleaved?

Accepted Answer

To minimize eddy currents and energy losses.

Answer

To enhance mechanical strength and stability.

Answer

To increase the magnetic flux density in the core.

Answer

To reduce noise and vibrations.

Question 43

What is the primary function of insulation in electrical transformers?

Accepted Answer

To prevent electrical breakdown and ensure safety.

Answer

To increase the magnetic flux density in the core.

Answer

To enhance heat dissipation and reduce energy losses.

Question 44

What is the primary purpose of tap-changing in electrical transformers?

Accepted Answer

To adjust the turns ratio and regulate output voltage.

Answer

To increase the power capacity of the transformer.

Answer

To reduce the leakage flux in the transformer.

Question 45

What is the main function of a Buchholz relay in an electrical transformer?

Accepted Answer

To detect abnormal gas pressure and protect against damage.

Answer

To prevent overcurrent conditions in the transformer.

Answer

To regulate the output voltage of the transformer.

Question 46

Explain the difference between a step-up transformer and a step-down transformer.

Accepted Answer

Step-up transformers increase voltage, while step-down transformers decrease voltage.

Answer

Step-up transformers increase current, while step-down transformers decrease current.

Answer

Step-up transformers have more primary windings, while step-down transformers have more secondary windings.

Question 47

**Which type of core material exhibits low hysteresis losses and is commonly used in power transformers?**

Accepted Answer

Laminated steel

Answer

Copper

Answer

Solid iron

Answer

Aluminum

Question 48

**What is the primary purpose of the windings in an electrical transformer?**

Accepted Answer

To conduct electricity and establish magnetic fields

Answer

To provide insulation

Answer

To dissipate heat

Answer

To offer structural support

Question 49

**What is the primary function of the tank in an electrical transformer?**

Accepted Answer

To house and protect the transformer components while providing cooling

Answer

To prevent electrical shock

Answer

To generate electricity

Question 50

**Which type of transformer is used to increase voltage levels?**

Accepted Answer

Step-up transformer

Answer

Isolation transformer

Answer

Autotransformer

Answer

Step-down transformer

Question 51

**What is the purpose of the bushings on an electrical transformer?**

Accepted Answer

To provide electrical insulation between the windings and the tank

Answer

To support the transformer core

Answer

To dissipate heat

Question 52

**What is the primary function of the magnetic core in a transformer?**

Accepted Answer

To provide a low-reluctance path for magnetic flux

Answer

To conduct electricity

Answer

To dissipate heat

Answer

To provide insulation

Question 53

**Which type of transformer is primarily used to isolate circuits electrically?**

Accepted Answer

Isolation transformer

Answer

Step-down transformer

Answer

Step-up transformer

Answer

Autotransformer

Question 54

**What is the purpose of the cooling system in an electrical transformer?**

Accepted Answer

To dissipate heat generated by the transformer during operation

Answer

To improve efficiency

Answer

To regulate voltage

Answer

To prevent short circuits