Question 1

The transformer that converts a high voltage from the power company down to 240/120 V for homes and businesses is called a(n) transformer.&#10;A) auto&#10;B) distribution&#10;C) control&#10;D) household

Accepted Answer

A distribution transformer is specifically designed to step down the high voltage from the power company to a lower voltage suitable for use in homes and businesses. Auto transformers are used for voltage regulation or impedance matching in electronic circuits, control transformers are used for powering control circuits, and there is no specific type of transformer called a household transformer.

Question 2

A transformer has a 240 V primary and a 60 V secondary. With a 5 ohm load connected, what is the primary current?&#10;A) 2 A&#10;B) 3 A&#10;C) 7 A&#10;D) 8 A

Accepted Answer

The transformer equation states that:

Vp / Vs = Ip / Is

where Vp is the primary voltage, Vs is the secondary voltage, Ip is the primary current, and Is is the secondary current.

Rearranging this equation gives:

Ip = (Vp / Vs) * Is

We know that Vp = 240 V, Vs = 60 V, and we can calculate Is using the load impedance and voltage:

Is = Vs / Zload
Is = 60 V / 5 ohms
Is = 12 A

Plugging these values into the previous equation gives:

Ip = (240 V / 60 V) * 12 A
Ip = 48 A / 60
Ip = 4 / 5
Ip = 0.8 A

Therefore, the correct answer is B) 0.8 A, which can be rounded up to 1 A.

Question 3

A transformer has a 2:1 turns ratio. 120 V is applied to the primary. What is the secondary voltage?&#10;A) 24 V&#10;B) 60 V&#10;C) 120 V&#10;D) 600 V

Accepted Answer

A 2:1 turns ratio means that the secondary voltage will be half of the primary voltage. Therefore, the secondary voltage will be 60 V.

Question 4

The power input winding of a transformer is called the winding.&#10;A) primary&#10;B) secondary&#10;C) tertiary&#10;D) tapped

Accepted Answer

The power input winding of a transformer is referred to as the primary winding.

Question 5

A tape-wound core is assembled by .&#10;A) stacking small individual sheets of metal&#10;B) winding a long continuous tape into a spiral&#10;C) casting a solid core and wrapping it with tape&#10;D) bolting together two halves

Accepted Answer

A tape-wound core is assembled by winding a long continuous tape into a spiral, which creates a strong and efficient core structure for use in electrical transformers and other applications. Stacking small individual sheets of metal, casting a solid core, and bolting together two halves are alternative methods of creating core structures, but they are not typically used for tape-wound cores.

Question 6

Any transformer flux that does not follow the core and escapes into the surrounding air is called .&#10;A) magnetizing flux&#10;B) flux coupling&#10;C) flux leakage&#10;D) flux reactance

Accepted Answer

Flux that does not follow the core and escapes into the surrounding air is called flux leakage. The other options, magnetizing flux and flux coupling, refer to flux that is within the core and used for power transmission. Flux reactance, on the other hand, is a measure of the opposition offered by the transformer to the flow of alternating current due to the presence of flux.

Question 7

A transformer supplying a house with 240/120 V has a secondary which is center tapped. The conductor connected to the center is called the conductor.&#10;A) equipment ground&#10;B) hot&#10;C) neutral&#10;D) ungrounded

Accepted Answer

The conductor connected to the center tap of the secondary winding of a transformer is called the neutral conductor. It is typically grounded and serves as a return path for the current flowing through the hot conductor.

Question 8

The industrial use transformer that normally has 240 V or 480 V primary and a 120 V secondary is called a(n) transformer.&#10;A) auto&#10;B) distribution&#10;C) isolation&#10;D) control

Accepted Answer

Control transformers are specifically designed to provide a high degree of secondary voltage stability during a brief period of overload condition (also known as 'inrush current'). These transformers are typically used in industrial environments to step down the voltage to a level suitable for the control circuits, which commonly operate at 120V. Hence, a transformer with a 240V or 480V primary and a 120V secondary is referred to as a control transformer.

Question 9

In a transformer, even when there is no load connected, there will be some small current flow known as current.&#10;A) excitation&#10;B) primary&#10;C) secondary&#10;D) hysteresis

Accepted Answer

The current that flows in a transformer when there is no load connected is called excitation current. This current is needed to create the magnetic field in the transformer necessary for the transfer of energy from the primary to the secondary winding.

Question 10

A transformer in which the secondary voltage is more than the primary voltage is called a(n) transformer.&#10;A) step-down&#10;B) step-up&#10;C) isolation&#10;D) auto

Accepted Answer

A step-up transformer increases the voltage from the primary to the secondary winding.

Question 11

Most transformer cores are assembled from many thin sheets of metal. This type of construction is called .&#10;A) laminated&#10;B) toroid&#10;C) H core&#10;D) tape wound

Accepted Answer

The answer of Most transformer cores are assembled from many...

Question 12

In a transformer, the turns of primary wire compared to the turns of secondary wire is called the ratio.&#10;A) isolation&#10;B) step-up&#10;C) step-down&#10;D) turns

Accepted Answer

The answer of In a transformer, the turns of primary...

Question 13

A transformer in which the secondary voltage is less than the primary voltage is called a(n) transformer.&#10;A) step-up&#10;B) isolation&#10;C) step-down&#10;D) auto

Accepted Answer

The answer of A transformer in which the secondary voltage...

Question 14

What is a magnetically operated device that can change values of voltage, current, and impedance without changing frequency?&#10;A) a converter&#10;B) an inverter&#10;C) a transformer&#10;D) a transistor

Accepted Answer

The answer of What is a magnetically operated device that...

Question 15

What type of core is often found on high-voltage distribution transformers?&#10;A) shell-type&#10;B) H-type&#10;C) tape-wound&#10;D) toroid

Accepted Answer

The answer of What type of core is often found...

Question 16

A transformer has a 240 V primary and a 120 V secondary. With a 30 ohm load connected, what is the primary volt- amps?&#10;A) 4&#10;B) 8&#10;C) 480&#10;D) 960

Accepted Answer

The answer of A transformer has a 240 V primary...

Question 17

A transformer in which the primary and secondary are physically separated and not connected by a conductor is called a(n) transformer.&#10;A) isolation&#10;B) step-up&#10;C) step-down&#10;D) turns

Accepted Answer

The answer of A transformer in which the primary and...

Question 18

A tape-wound core is also called a(n) core.&#10;A) toroid&#10;B) solid&#10;C) H&#10;D) E

Accepted Answer

The answer of A tape-wound core is also called a(n)...

Question 19

The output winding of a transformer is called the winding.&#10;A) primary&#10;B) secondary&#10;C) tertiary&#10;D) tapped

Accepted Answer

The answer of The output winding of a transformer is...

Question 20

An isolation transformer has the same input and output voltages.

Accepted Answer

The answer of An isolation transformer has the same input...

Question 21

A transformer that has one winding, which is used for both the primary and secondary, is called a(n) .&#10;A) distribution transformer&#10;B) step-up transformer&#10;C) autotransformer&#10;D) control transformer

Accepted Answer

The answer of A transformer that has one winding, which...

Question 22

The amount of current that flows into a transformer primary when voltage is first applied is called current.&#10;A) magnetizing&#10;B) excitation&#10;C) activating&#10;D) inrush

Accepted Answer

The answer of The amount of current that flows into...

Deck 28: Single-Phase Transformers