Electrical Transformers: Types, Maintenance, and Applications

Question 1

In electrical power distribution systems, which transformer type is primarily used to lower voltage from transmission levels to distribution levels?

Accepted Answer

Distribution transformer

Answer

Autotransformer

Answer

Instrument transformer

Answer

Power transformer

Question 2

Which transformer type is primarily used to prevent current flow between circuits and provide electrical isolation?

Accepted Answer

Isolation transformer

Answer

Power transformer

Answer

Distribution transformer

Answer

Autotransformer

Question 3

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

Accepted Answer

Allow magnetic flux to flow

Answer

Minimize eddy current losses

Answer

Provide electrical insulation

Answer

Store electrical energy

Question 4

What is the purpose of the turns ratio in a transformer?

Accepted Answer

Determines the voltage ratio between the primary and secondary windings

Answer

Controls the current flowing through the transformer

Answer

Isolates the primary and secondary circuits

Answer

Regulates the output voltage of the transformer

Question 5

Which test is commonly used to measure the insulation resistance of a transformer?

Accepted Answer

Megger test

Answer

Hi-pot test

Answer

Short circuit test

Answer

Open circuit test

Question 6

What is the primary purpose of a conservator tank on a transformer?

Accepted Answer

Compensate for oil volume changes due to temperature variations

Answer

Provide electrical insulation between core and windings

Answer

Dissipate heat from the transformer

Answer

Store the transformer's magnetic field

Question 7

Which type of transformer is typically used to reduce voltage from transmission lines for distribution purposes?

Accepted Answer

Distribution transformer

Answer

Autotransformer

Answer

Power transformer

Answer

Isolation transformer

Question 8

What is the primary function of a bushing in a transformer?

Accepted Answer

Provide electrical insulation between the transformer and external conductors

Answer

Regulate the voltage output of the transformer

Answer

Dissipate heat from the transformer

Answer

Store the transformer's magnetic field

Question 9

What is the main reason for laminating the core of a transformer?

Accepted Answer

To prevent eddy currents

Answer

To increase the magnetic flux density

Answer

To reduce hysteresis losses

Answer

To improve voltage regulation

Question 10

What is the primary function of a transformer?

Accepted Answer

To change the voltage level of an AC signal

Answer

To convert AC to DC

Answer

To provide electrical isolation

Answer

To regulate the frequency of an AC signal

Question 11

Which type of winding in a transformer is directly connected to the power source?

Accepted Answer

Primary winding

Answer

Secondary winding

Answer

Tertiary winding

Answer

Compensation winding

Question 12

What is the ideal turns ratio for a transformer operating under no-load conditions?

Accepted Answer

1:1

Answer

2:1

Answer

1:2

Answer

Depends on the load impedance

Question 13

What is the purpose of cooling fins on a transformer?

Accepted Answer

To increase the surface area for heat dissipation

Answer

To improve the magnetic flux density

Answer

To reduce noise levels

Answer

To prevent short circuits

Question 14

Which of the following is NOT a type of electrical transformer?

Accepted Answer

Generator

Answer

Power transformer

Answer

Distribution transformer

Answer

Autotransformer

Question 15

The primary function of a transformer is to:

Accepted Answer

Change the voltage or current of an AC signal

Answer

Change the frequency of an AC signal

Answer

Convert AC to DC

Answer

Store electrical energy

Question 16

Which part of a transformer is responsible for creating the magnetic field that induces voltage in the secondary winding?

Accepted Answer

Core

Answer

Primary winding

Answer

Secondary winding

Answer

Insulation

Question 17

What is the ideal power factor for a transformer operating at full load?

Accepted Answer

1.0

Answer

0.5

Answer

0.707

Answer

0.9

Question 18

What is the purpose of a Buchholz relay in a transformer?

Accepted Answer

To detect abnormal gas pressure caused by internal faults

Answer

To prevent overloads

Answer

To regulate voltage

Answer

To isolate the transformer from the system

Question 19

How is the voltage ratio of a transformer related to the turns ratio?

Accepted Answer

Voltage ratio = Turns ratio

Answer

Voltage ratio = Inverse of turns ratio

Answer

Voltage ratio = Square of turns ratio

Answer

Voltage ratio = Cube of turns ratio

Question 20

Which of the following is NOT a benefit of using transformers in electrical systems?

Accepted Answer

Energy storage

Answer

Voltage regulation

Answer

Isolation

Answer

Power factor improvement

Question 21

What is the purpose of a conservator tank in a transformer?

Accepted Answer

To store excess oil and allow for thermal expansion

Answer

To prevent moisture from entering the transformer

Answer

To provide a cooling mechanism

Answer

To house the transformer windings

Question 22

To troubleshoot a transformer suspected of winding faults, what should be measured first?

Accepted Answer

Winding resistance

Answer

Core insulation

Answer

Turns ratio

Answer

Dielectric strength

Question 23

Why are regular transformer inspections essential?

Accepted Answer

To identify potential problems and take corrective actions early on.

Answer

To ensure compliance with industry standards.

Answer

To improve transformer efficiency and lifespan.

Answer

To fulfill insurance requirements.

Question 24

In a three-phase electrical system, which transformer connection configuration is most commonly used?

Accepted Answer

Star-Star

Answer

Delta-Delta

Answer

Star-Zigzag

Answer

Zigzag-Delta

Question 25

In electrical power transmission and distribution systems, what is the primary function of transformers?

Accepted Answer

Adjusting voltage levels to meet varying requirements

Answer

Minimizing power loss in transmission lines

Answer

Increasing overall power consumption within a circuit

Answer

Providing protection against electrical short circuits

Question 26

Which of the following is NOT a significant source of energy loss in electrical transformers?

Accepted Answer

Mechanical vibration

Answer

Eddy current loss

Answer

Dielectric loss

Question 27

Which of the following is NOT a type of electrical transformer?

Accepted Answer

Solid-State Transformer

Answer

Distribution Transformer

Answer

Instrument Transformer

Answer

Power Transformer

Question 28

What is the primary function of a Step-Up Transformer?

Accepted Answer

Increase Voltage

Answer

Regulate Voltage

Answer

Isolating circuits

Question 29

Which material is commonly used for transformer cores?

Accepted Answer

Laminated Steel

Answer

Plastic

Answer

Copper

Answer

Aluminum

Question 30

What is the purpose of an insulation layer in a transformer?

Accepted Answer

Prevent electrical breakdown

Answer

Dissipate heat

Answer

Reduce noise

Answer

Improve efficiency

Question 31

What is the consequence of loading a transformer beyond its rated capacity?

Accepted Answer

Reduced efficiency and increased heat

Answer

No significant effect

Question 32

What is the role of the magnetic circuit in a transformer?

Accepted Answer

Facilitate path for magnetic flux with minimum reluctance

Answer

Convert electrical energy into mechanical energy

Answer

Store energy

Answer

Isolate Primary and Secondary windings

Question 33

When disposing of or recycling transformers, which environmental factor is of utmost importance?

Accepted Answer

Presence of hazardous materials

Answer

Physical dimensions and weight

Answer

Energy efficiency rating

Question 34

Which material is primarily used to construct transformer cores, minimizing energy losses?

Accepted Answer

Laminated silicon steel

Answer

Pure copper

Answer

Cast aluminum

Answer

Solid iron

Question 35

In oil-immersed transformers, what is the primary function of the oil?

Accepted Answer

Provide insulation and facilitate heat dissipation

Answer

Generate magnetic flux

Answer

Lubricate moving parts

Answer

Enhance electrical conductivity

Question 36

Which type of transformer elevates voltage from a lower level to a higher level?

Accepted Answer

Step-up transformer

Answer

Step-down transformer

Answer

Autotransformer

Answer

Isolation transformer

Question 37

What is the primary function of the primary winding in a transformer?

Accepted Answer

Receive electrical energy from the power source

Answer

Step down voltage and increase current

Answer

Provide electrical isolation

Question 38

Which test is commonly employed to determine the integrity of transformer insulation?

Accepted Answer

Insulation resistance test

Answer

Continuity test

Answer

Polarity test

Question 39

What is the result of increasing the number of turns on the primary winding of a transformer?

Accepted Answer

Increased output voltage and decreased output current

Answer

Increased both output voltage and current

Answer

Decreased output voltage and increased output current

Question 40

When working on transformers, which safety precaution is essential to prioritize?

Accepted Answer

Wear appropriate personal protective equipment (PPE), de-energize and discharge the transformer

Answer

Touch transformer terminals to detect heat

Answer

Use a voltmeter to verify voltage absence

Question 41

Which of the following is NOT a type of electrical transformer?

Accepted Answer

Inductor

Answer

Power transformer

Answer

Distribution transformer

Answer

Isolation transformer

Question 42

What is the primary function of a transformer core?

Accepted Answer

Provides a low-reluctance path for magnetic flux

Answer

Regulates voltage

Answer

Insulates the windings

Answer

Stores energy

Question 43

What is the main benefit of using a laminated transformer core?

Accepted Answer

Reduces eddy current losses

Answer

Increases transformer efficiency

Answer

Improves voltage regulation

Answer

Enhances transformer insulation

Question 44

Which of the following is a primary application of distribution transformers?

Accepted Answer

Power distribution to residential and commercial areas

Answer

High-voltage transmission

Answer

Railway traction

Answer

Industrial power generation

Question 45

What is the primary purpose of transformer oil?

Accepted Answer

Cooling and insulation

Answer

Voltage regulation

Answer

Current limiting

Answer

Impedance matching

Question 46

Which of the following tests is used to evaluate the condition of transformer insulation?

Accepted Answer

Insulation resistance test

Answer

Continuity test

Answer

Polarity test

Answer

Turns ratio test

Question 47

Which of the following conditions can lead to transformer overheating?

Accepted Answer

Overloading

Answer

Clean windings

Answer

Underloading

Answer

Proper cooling

Question 48

What is the fundamental difference between a step-up and a step-down transformer?

Accepted Answer

Step-up transformer increases voltage, while step-down transformer decreases voltage

Answer

Step-up transformer increases current, while step-down transformer decreases current

Answer

Step-up transformer uses more primary winding turns, while step-down transformer uses fewer turns

Question 49

What material is most commonly used for the core of an electrical transformer?

Accepted Answer

Laminated steel sheets

Answer

Aluminum plates

Answer

Ceramic insulators

Answer

Copper wire

Question 50

What is the main function of the windings in an electrical transformer?

Accepted Answer

To create a changing magnetic field

Answer

To protect the transformer from overheating

Answer

To store electrical energy like a battery

Answer

To directly conduct electricity between circuits

Question 51

If you need to reduce voltage from a power source, which type of transformer would you use?

Accepted Answer

Step-down transformer

Answer

Autotransformer

Answer

Isolation transformer

Answer

Step-up transformer

Question 52

In a transformer, how do the number of turns in the windings relate to the voltage in the primary and secondary coils?

Accepted Answer

The ratio of primary voltage to secondary voltage equals the ratio of primary turns to secondary turns.

Answer

The product of primary voltage and secondary voltage equals the product of primary turns and secondary turns.

Answer

Primary and secondary voltages are always equal, regardless of the number of turns.

Answer

The ratio of primary voltage to secondary voltage is the inverse of the ratio of primary turns to secondary turns.

Question 53

Why is oil commonly used in large electrical transformers?

Accepted Answer

To insulate and cool the transformer

Answer

To prevent rust and corrosion of the metal parts

Answer

To lubricate moving parts inside the transformer

Answer

To increase the overall electrical efficiency

Question 54

What is the purpose of a tap changer on a transformer?

Accepted Answer

To make small adjustments to the output voltage

Answer

To automatically shut off the transformer during an overload

Answer

To improve the transformer's energy efficiency rating

Answer

To electrically isolate the transformer from the power grid

Question 55

How do you calculate the efficiency of an electrical transformer?

Accepted Answer

Divide the output power by the input power, then multiply by 100%

Answer

Divide the input power by the output power, then multiply by 100%

Answer

Subtract the input power from the output power, then multiply by 100%

Answer

Subtract the output power from the input power, then divide by 100