Question 1

An isolation transformer whose main purpose is to reduce voltage spikes will have a turns ratio of ____.
A) 1 to 1
B) 1 to 5
C) 5 to 1
D) 2 to 1

Accepted Answer

An isolation transformer with a turns ratio of 1 to 1 is designed to isolate the secondary circuit from the primary circuit without changing the voltage level, which helps in reducing voltage spikes and electrical noise.

Question 2

A(n) ____________________ is a magnetically operated machine that can change values of voltage, current, and impedance without a change of frequency.

Accepted Answer

transformer

Question 3

Primary transformer windings are labeled with the letter ____.
A) S
B) X
C) P
D) H

Accepted Answer

Primary transformer windings are labeled with the letter H, while secondary windings are labeled with the letter X. S and P are not typically used to label transformer windings.

Question 4

A good rule for any transformer is that ____ in must equal ____ out.
A) voltage, voltage
B) power, power
C) amperage, amperage
D) resistance, resistance

Accepted Answer

The power input to a transformer equals the power output, meaning that the voltage and amperage may change, but the overall energy remains the same. Therefore, choice B is the correct answer.

Question 5

When testing a transformer, if one lead of an ohmmeter is connected to a primary winding lead and the other is connected to a secondary winding lead, you are checking the transformer for ____.
A) shorted windings
B) grounds
C) continuity
D) voltage

Accepted Answer

When an ohmmeter is connected this way, it checks for continuity between the primary and secondary windings, indicating a shorted winding. It does not check for grounds or voltage.

Question 6

Secondary windings of transformers are labeled with the letter ____.
A) S
B) X
C) P
D) H

Accepted Answer

Secondary windings of transformers are typically labeled with the letter "X". This helps distinguish them from primary windings, which are often labeled with the letter "P".

Question 7

If a transformer has 1000 turns in the primary winding and 100 turns in the secondary winding, the turns ratio of this transformer is ____.
A) 1 to 10
B) 10 to 1
C) 100,000 to 1
D) 10,000 to 1

Accepted Answer

The turns ratio of a transformer is defined as the ratio of the number of turns in the primary winding to the number of turns in the secondary winding. In this case, the turns ratio is 1000:100 or 10:1. Therefore, the correct answer is B, 10 to 1.

Question 8

____ are one-winding transformers.
A) Control transformers
B) Autotransformers
C) Distribution transformers
D) Isolation transformers

Accepted Answer

Autotransformers are single-winding transformers where a portion of the winding acts as both the primary and secondary winding. The other options listed are all multi-winding transformers.

Question 9

The amount of core material needed for a particular transformer is determined by the ____ rating of the transformer.
A) voltage
B) amperage
C) power
D) resistance

Accepted Answer

The amount of core material required for a transformer depends on its power rating, which is expressed in watts or volt-amperes (VA). The amperage rating of a transformer is important for selecting the appropriate wire gauge for the winding, but it does not directly affect the size of the core. Voltage and resistance ratings are also important for transformer design, but they do not determine the amount of core material needed.

Question 10

____ are often used by power companies to provide voltage regulation to large power lines.
A) Isolation transformers
B) Distribution transformers
C) Control transformers
D) Autotransformers

Accepted Answer

Autotransformers are often used for voltage regulation in large power lines because they are efficient and cost-effective, as they use a single winding instead of two separate windings like other types of transformers.

Question 11

All values of a transformer are ____ its turns ratio.
A) the square of
B) the square root of
C) equal to
D) proportional to

Accepted Answer

All values of a transformer, such as voltage, current, and power, are directly proportional to its turns ratio. This is because the turns ratio determines the ratio of voltage and current in the primary and secondary coils of the transformer.

Question 12

The polarity of transformer windings can be determined by connecting them as a(n) ____ and testing them for additive or subtractive polarity.
A) isolation transformer
B) control transformer
C) distribution transformer
D) autotransformer

Accepted Answer

The autotransformer is commonly used for polarity testing of transformer windings. By connecting the windings in series with the autotransformer, the resulting voltage can be used to determine the additive or subtractive polarity of the transformer windings.

Question 13

The ability of one coil to induce a voltage into another coil is called ____ induction.
A) excitation
B) ratio
C) voltage
D) mutual

Accepted Answer

The ability of one coil to induce a voltage into another coil is called mutual induction.

Question 14

When testing a transformer, if one ohmmeter lead is connected to a transformer winding and the other is connected to the transformer frame, you are testing the transformer for ____.
A) shorted windings
B) grounds
C) continuity
D) voltage

Accepted Answer

Connecting one ohmmeter lead to a transformer winding and the other to the transformer frame tests for grounds in the transformer. This is because the frame of the transformer should not be electrically conductive and any continuity between the winding and the frame indicates a ground fault. Testing for shorted windings and continuity typically requires different connections and configurations. Testing for voltage would require connecting the transformer to a power source and measuring the output voltage.

Question 15

The polarity notation used for transformers with more than one primary or secondary winding is a ____.
A) dot
B) line
C) dotted line
D) letter X

Accepted Answer

The polarity notation used for transformers with more than one primary or secondary winding is a dot. This dot notation indicates the relative polarity of the windings, helping to ensure correct phase relationships when connecting transformers.

Question 16

The ____ current is the amount of current required to magnetize the core of the transformer.
A) start-up
B) control
C) excitation
D) ratio

Accepted Answer

The excitation current is the amount of current required to magnetize the core of the transformer.

Question 17

The transformer ____ is determined by calculating the percentage of variable voltage as compared to the rated voltage of the high voltage winding.
A) rating
B) voltage
C) impedance
D) amperage

Accepted Answer

The transformer impedance is determined by calculating the percentage of variable voltage as compared to the rated voltage of the high voltage winding. This measurement is crucial for understanding how the transformer will behave under different load conditions.

Question 18

If a transformer has several taps on the primary winding and no taps on the secondary winding, it can be connected to different primary voltages without changing the value of the secondary ____.
A) amperage
B) resistance
C) voltage
D) wattage

Accepted Answer

The number of turns on the secondary winding remains constant regardless of the primary voltage, so the voltage output will remain the same. The amperage, resistance, and wattage on the secondary side will depend on the load and the primary voltage.

Question 19

In a distribution transformer, the center tap is grounded and becomes the ____ conductor.
A) distribution
B) ungrounded
C) grounding
D) neutral

Accepted Answer

The center tap in a distribution transformer is connected to ground and becomes the neutral conductor, which can help balance the voltage on both sides of the transformer.

Question 20

When testing a transformer, if one ohmmeter lead is connected to the lead of a transformer winding and the other ohmmeter lead is connected to the other lead of the same winding, you are testing the transformer for ____.
A) shorted windings
B) grounds
C) continuity
D) voltage

Accepted Answer

When you connect an ohmmeter across the leads of the same transformer winding, you are testing for continuity to ensure that the winding forms a complete, unbroken electrical path.

Quiz 18: Single-Phase Transformers

An isolation transformer whose main purpose is to reduce voltage spikes will have a turns ratio of ____.

A(n) ____________________ is a magnetically operated machine that can change values of voltage, current, and impedance without a change of frequency.

Primary transformer windings are labeled with the letter ____.

A good rule for any transformer is that in must equal out.

When testing a transformer, if one lead of an ohmmeter is connected to a primary winding lead and the other is connected to a secondary winding lead, you are checking the transformer for ____.

Secondary windings of transformers are labeled with the letter ____.

If a transformer has 1000 turns in the primary winding and 100 turns in the secondary winding, the turns ratio of this transformer is ____.

____ are one-winding transformers.

The amount of core material needed for a particular transformer is determined by the ____ rating of the transformer.

____ are often used by power companies to provide voltage regulation to large power lines.

All values of a transformer are ____ its turns ratio.

The polarity of transformer windings can be determined by connecting them as a(n) ____ and testing them for additive or subtractive polarity.

The ability of one coil to induce a voltage into another coil is called ____ induction.

When testing a transformer, if one ohmmeter lead is connected to a transformer winding and the other is connected to the transformer frame, you are testing the transformer for ____.

The polarity notation used for transformers with more than one primary or secondary winding is a ____.

The ____ current is the amount of current required to magnetize the core of the transformer.

The transformer ____ is determined by calculating the percentage of variable voltage as compared to the rated voltage of the high voltage winding.

If a transformer has several taps on the primary winding and no taps on the secondary winding, it can be connected to different primary voltages without changing the value of the secondary ____.

In a distribution transformer, the center tap is grounded and becomes the ____ conductor.

When testing a transformer, if one ohmmeter lead is connected to the lead of a transformer winding and the other ohmmeter lead is connected to the other lead of the same winding, you are testing the transformer for ____.