AC-AC Transformers

Question 1

What do AC-AC transformers do?

Answer 1

AC-AC transformers transfer electrical energy between circuits, changing voltage and current levels while isolating circuits.

Question 2

How do transformers work?

Answer 2

They operate on the principle of electromagnetic induction, transferring energy between primary and secondary windings through a magnetic core.

Question 3

What are the main types of transformers?

Answer 3

Step-up, step-down, isolation, autotransformers, and current transformers.

Question 4

What is a step-up transformer?

Answer 4

A transformer that increases voltage from the primary to the secondary winding.

Question 5

What is a step-down transformer?

Answer 5

A transformer that decreases voltage from the primary to the secondary winding.

Question 6

What is an isolation transformer?

Answer 6

A transformer with a 1:1 turns ratio used to electrically isolate two circuits.

Question 7

What is an autotransformer?

Answer 7

A transformer with a single winding that acts as both primary and secondary, sharing part of the winding.

Question 8

What is a current transformer (CT)?

Answer 8

A transformer used to measure current in high-power circuits by producing a proportional lower current.

Question 9

What is the turns ratio in a transformer?

Answer 9

The ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

Question 10

How do you calculate the voltage ratio of a transformer?

Answer 10

Vsecondary/Vprimary = Nsecondary/Nprimary

Where N is the number of turns.

Question 11

What is the efficiency of a transformer?

Answer 11

The ratio of output power to input power, typically expressed as a percentage.

Question 12

What is the purpose of the core in a transformer?

Answer 12

To provide a path for the magnetic flux, improving efficiency and reducing losses.

Question 13

What materials are used for transformer cores?

Answer 13

Laminated iron, ferrite, or powered iron, depending on the frequency and power requirements.

Question 14

What is the role of insulation in a transformer?

Answer 14

To prevent electrical short circuits between windings and the core.

Question 15

What is a laminated core transformer?

Answer 15

A transformer with a core made of thin, insulated layers of iron to reduce eddy current losses.

Question 16

What are eddy currents in transformers?

Answer 16

Circulating currents induced in the core, causing power loss and heat generation.

Question 17

What is a toroidal transformer?

Answer 17

A transformer with a doughnut-shaped core, offering higher efficiency and lower electromagnetic interference.

Question 18

What is the impedance of a transformer?

Answer 18

The opposition to alternating current, determined by the winding resistance and leakage reactance.

Question 19

What is a center-tapped transformer?

Answer 19

A transformer with a secondary winding that has a connection in the middle, providing two equal voltages.

Question 20

What is a multitap transformer?

Answer 20

A transformer with multiple taps on the winding to provide different voltage outputs.

Question 21

What is the purpose of a multitap transformer?

Answer 21

To provide multiple voltage levels for different circuit requirements.

Question 22

What is a three-phase transformer?

Answer 22

A transformer designed to work with three-phase power systems, often used in industrial applications.

Question 23

How are transformers cooled?

Answer 23

Through air, oil, or forced cooling systems to dissipate heat generated during operation.

Question 24

What is a transformer regulation?

Answer 24

The change in output voltage from no load to full load, expressed as a percentage.

Question 25

What is the primary purpose of transformer shielding?

Answer 25

To reduce electromagnetic interference (EMI) between the primary and secondary windings.

Question 26

What is a leakage flux in transformers?

Answer 26

Magnetic flux that does not link both windings, reducing efficiency.

Question 27

What are common applications of transformers?

Answer 27

Power distribution, voltage regulation, impedance matching, and isolation.

Question 28

What can go wrong with transformers?

Answer 28

Overheating, insulation breakdown, core saturation, or winding damage.

Question 29

What is core saturation in a transformer?

Answer 29

When the core's magnetic material reaches its maximum flux density, causing distortion and inefficiency.

Question 30

How do you test a transformer?

Answer 30

Use a multimeter to measure winding resistance, and apply test voltages to verify the turns ratio and functionality.

Question 31

What is a harmonic distortion in transformers?

Answer 31

Distortion caused by non-linear loads, affecting transformer efficiency and performance.

Question 32

What is the role of a transformer in voltage step-down applications?

Answer 32

To reduce high voltage to a lower, usable level for devices or circuits.

Question 33

What is the purpose of a transformer in power isolation?

Answer 33

To separate two circuits electrically while allowing power transfer, enhancing safety.

Question 34

What is the no-load current of a transformer?

Answer 34

The current drawn by the primary winding when the secondary circuit is open.

Question 35

How do you calculate the power rating of a transformer?

Answer 35

Multiplying the secondary voltage by the secondary current, typically expressed in volt-amperes (VA).

Question 36

What is a shell-type transformer?

Answer 36

A transformer with the windings surrounded by the core, offering better magnetic flux containment.

Question 37

What is the difference between step-up and step-down transformers?

Answer 37

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

Question 38

What is the purpose of a magnetic shunt in a transformer?

Answer 38

To control the amount of leakage flux and regulate the output voltage.

Question 39

What is a split-core transformer?

Answer 39

A transformer with a removable core, used for current sensing without disconnecting the circuit.

Question 40

How do transformers improve energy efficiency in power distribution?

Answer 40

By stepping up voltage to reduce current and minimize power loss during transmission.