Question 1

If a transformer has a ratio of 10 to 1 (10:1), it is being used as a(n) ____ transformer.&#10;A) step-up&#10;B) step-down&#10;C) buck-boost&#10;D) tapped

Accepted Answer

B

Question 2

Transformers used for power distribution are wound on cores made of ____.&#10;A) iron or steel&#10;B) nonconducting material&#10;C) aluminum&#10;D) antimony

Accepted Answer

Transformers used for power distribution require a high magnetic permeability to efficiently transfer power. Iron or steel cores have high magnetic permeability and are commonly used in power distribution transformers. Nonconducting materials would not provide sufficient magnetic properties, aluminum has lower magnetic properties and is less efficient, and antimony is not commonly used in transformer cores.

Question 3

A(n) ____ is used for installations where heavy loads are used infrequently or where it is apparent that future demand may require additional loading.&#10;A) autotransformer&#10;B) instrument transformer&#10;C) tapped transformer&#10;D) buck-boost transformer

Accepted Answer

A tapped transformer is designed to provide multiple voltage outputs from a single input voltage. This makes it suitable for installations where heavy loads may be used infrequently, as different taps on the transformer can be used to adjust the voltage to match the load. Additionally, if future demand requires additional loading, the transformer can be re-tapped to provide a higher voltage output. Autotransformers, instrument transformers, and buck-boost transformers are not designed to provide multiple voltage outputs, and may not be suitable for installations with varying load requirements.

Question 4

The coils of an air core transformer are wound on forms made of nonconducting materials.

Accepted Answer

The forms on which the coils are wound are made of nonconducting material to prevent any interference with the electromagnetic field.

Question 5

The type of material from which the core is made affects the efficiency of the transformer.

Accepted Answer

The type of material used for the core affects the magnetic flux and hence the efficiency of the transformer. Different materials have different magnetic permeability and hysteresis losses which can impact the transformer's efficiency.

Question 6

One method of transformer construction is to build up thin, flat sections called ____.&#10;A) intertwined coils&#10;B) pancake coils&#10;C) nested coils&#10;D) laminated coils

Accepted Answer

The method described is known as the pancake coil technique. This involves layering thin, flat sections to create a compact and efficient transformer design.

Question 7

What is one method of cooling a transformer?&#10;A) place in a tank of refrigerant&#10;B) place in an air-conditioned room&#10;C) place in a tank of water&#10;D) place in a tank of oil

Accepted Answer

The most common method of cooling a transformer is through a tank filled with oil, which is circulated through the windings and core of the transformer to dissipate heat. The oil has high heat capacity and can absorb a large amount of heat generated by the transformer, allowing for efficient cooling.

Question 8

Air core transformers are ____.&#10;A) efficient&#10;B) inefficient&#10;C) as efficient as iron/steel core transformers&#10;D) about 30 percent efficient

Accepted Answer

Air core transformers are generally considered inefficient compared to iron or steel core transformers because the absence of a solid core results in a lower magnetic coupling between the coils.

Question 9

If a transformer increases the voltage, it is called a ____ transformer.&#10;A) step-up&#10;B) step-down&#10;C) buck-boost&#10;D) tapped

Accepted Answer

A step-up transformer is designed to increase the voltage.

Question 10

Small transformers, such as those used for doorbell and signal circuits, are usually very efficient.

Accepted Answer

The answer of Small transformers, such as those used for...

Question 11

The molecular motion caused by the magnetizing and demagnetizing of a transformer's core results in friction which produces heat. This heat loss plus the power loss caused by the magnetic lag is called the ____ loss.

A) phase
B) copper
C) friction
D) hysteresis

Accepted Answer

The answer of The molecular motion caused by the magnetizing...

Question 12

The efficiency of a transformer may be as high as ____ percent.&#10;A) 85&#10;B) 90&#10;C) 99&#10;D) 100

Accepted Answer

The answer of The efficiency of a transformer may be...

Question 13

If a transformer's primary winding has 200 turns and the secondary winding has 600 turns, the turns ratio is ____.&#10;A) 1:4&#10;B) 4:1&#10;C) 1:3&#10;D) 3:1

Accepted Answer

The answer of If a transformer's primary winding has 200...

Question 14

A transformer's audible hum is a result of the laminations and windings vibrating as the magnetic field alternates.

Accepted Answer

The answer of A transformer's audible hum is a result...

Question 15

When transformers are constructed, the windings are often placed on separate legs to minimize flux leakage.

Accepted Answer

The answer of When transformers are constructed, the windings are...

Deck 12: Transformers