Deck 28: Single-Phase Transformers

Question 1

In a transformer, even when there is no load connected, there will be some small current flow known as _____ current.

A) excitation
B) primary
C) secondary
D) hysteresis

Answer 1

A

Question 2

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.

A) auto
B) distribution
C) control
D) household

Answer 2

B

Question 3

A transformer in which the secondary voltage is more than the primary voltage is called a(n) _____ transformer.

A) step-down
B) step-up
C) isolation
D) auto

Answer 3

B

Question 4

Any transformer flux that does not follow the core and escapes into the surrounding air is called _____.

A) magnetizing flux
B) flux coupling
C) flux leakage
D) flux reactance

Question 5

A transformer in which the secondary voltage is less than the primary voltage is called a(n) _____ transformer.

A) step-up
B) isolation
C) step-down
D) auto

Question 6

What is a magnetically operated device that can change values of voltage, current, and impedance without changing frequency?

A) a converter
B) an inverter
C) a transformer
D) a transistor

Question 7

What type of core is often found on high-voltage distribution transformers?

A) shell-type
B) H-type
C) tape-wound
D) toroid

Question 8

A tape-wound core is assembled by _____.

A) stacking small individual sheets of metal
B) winding a long continuous tape into a spiral
C) casting a solid core and wrapping it with tape
D) bolting together two halves

Question 9

A transformer in which the primary and secondary are physically separated and not connected by a conductor is called a(n) _____ transformer.

A) isolation
B) step-up
C) step-down
D) turns

Question 10

An isolation transformer has the same input and output voltages.

Question 11

The industrial use transformer that normally has 240 V or 480 V primary and a 120 V secondary is called a(n) _____ transformer.

A) auto
B) distribution
C) isolation
D) control

Question 12

A transformer has a 2:1 turns ratio. 120 V is applied to the primary. What is the secondary voltage?

A) 24 V
B) 60 V
C) 120 V
D) 600 V

Question 13

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.

A) equipment ground
B) hot
C) neutral
D) ungrounded

Question 14

A transformer has a 240 V primary and a 60 V secondary. With a 5 ohm load connected, what is the primary current?

A) 2 A
B) 3 A
C) 7 A
D) 8 A

Question 15

Most transformer cores are assembled from many thin sheets of metal. This type of construction is called _____.

A) laminated
B) toroid
C) H core
D) tape wound

Question 16

The output winding of a transformer is called the _____ winding.

A) primary
B) secondary
C) tertiary
D) tapped

Question 17

A tape-wound core is also called a(n) _____ core.

A) toroid
B) solid
C) H
D) E

Question 18

A transformer has a 240 V primary and a 120 V secondary. With a 30 ohm load connected, what is the primary volt-amps?

A) 4
B) 8
C) 480
D) 960

Question 19

In a transformer, the turns of primary wire compared to the turns of secondary wire is called the _____ ratio.

A) isolation
B) step-up
C) step-down
D) turns

Question 20

The power input winding of a transformer is called the _____ winding.

A) primary
B) secondary
C) tertiary
D) tapped

Question 21

A transformer that has one winding, which is used for both the primary and secondary, is called a(n) _____.

A) distribution transformer
B) step-up transformer
C) autotransformer
D) control transformer

Question 22

The amount of current that flows into a transformer primary when voltage is first applied is called _____ current.

A) magnetizing
B) excitation
C) activating
D) inrush