# Quiz 19: Transformers

Business

Q 1Q 1

What electrical quantity cannot be changed by a transformer?
A) Voltage
C) Impedance
B) Current
D) Frequency

Free

Multiple Choice

D

Q 2Q 2

A transformer has a turns ratio of 2.5:1. The primary voltage is 208 V. What is the voltage of the secondary winding?
A) 520 V
C) 83.2 V
B) 360.26 V
D) 120 V

Free

Multiple Choice

C

Q 3Q 3

A transformer has a turns ratio of 2.5:1. The primary voltage is 208 V. The secondary current is 18 A. What is the primary current?
A) 7.2 A
C) 45 A
B) 83.2 A
D) 11.56 A

Free

Multiple Choice

A

Q 4Q 4

A transformer has a turns ratio of 1:3. The primary voltage is 120 V. What is the secondary voltage?
A) 40 V
C) 240 V
B) 84 V
D) 360 V

Free

Multiple Choice

Q 5Q 5

A transformer has a turns ratio of 1:3. The primary voltage is 120 V. The secondary current is 1.2 A. What is the primary current?
A) 0.4 A
C) 2.4 A
B) 0.84 A
D) 3.6 A

Free

Multiple Choice

Q 6Q 6

An autotransformer ____.
A) has its primary and secondary windings electrically and mechanically separated from each other
B) uses the same winding for both the primary and secondary windings
C) produces a lower secondary voltage than the primary voltage
D) produces a higher secondary voltage than the primary voltage

Free

Multiple Choice

Q 7Q 7

A transformer that has 480 V applied to its primary winding and produces 120 V at its secondary winding is called a(n) ____.
A) autotransformer
C) step-up transformer
B) isolation transformer
D) step-down transformer

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Multiple Choice

Q 8Q 8

Which of the following statements is true for a wye-connected three-phase system?
A) Line current is higher than phase current by a factor of 1.732.
B) Phase current is higher than line current by a factor of 1.732.
C) Line current is less than phase current by a factor of 1.732.
D) Line current and phase current are equal.

Free

Multiple Choice

Q 9Q 9

Which of the following statements is true for a delta-connected three-phase system?
A) Line current is higher than phase current by a factor of 1.732.
B) Phase current is higher than line current by a factor of 1.732.
C) Line current is less than phase current by a factor of 1.732.
D) Line current and phase current are equal.

Free

Multiple Choice

Q 10Q 10

The windings of an alternator are delta connected. The alternator is producing a line-to-line voltage of 480 V. What is the value of the phase voltage?
A) 480 V
C) 277 V
B) 120 V
D) 831 V

Free

Multiple Choice

Q 11Q 11

The windings of an alternator are delta connected. The alternator is producing a line-to-line voltage of 480 V. A connected load draws 25.98 A of line current. What is the value of the phase current?
A) 25.98 A
C) 15 A
B) 45 A
D) 17.32 A

Free

Multiple Choice

Q 12Q 12

A three-phase wye-connected load is connected to a 480 V three-phase line. The line current is 36 A. If this load is purely resistive, what is the total amount of power being used in this circuit?
A) 51.84 kW
C) 7.48 kW
B) 29.93 kW
D) 12.96 kW

Free

Multiple Choice

Q 13Q 13

A delta-connected three-phase load is connected to a 560 V line. The loads have an impedance of 14 per phase. What is the apparent power of this connection?
A) 22.39 kVA
C) 38.8 kVA
B) 116.39 kVA
D) 67.2 kVA

Free

Multiple Choice

Q 14Q 14

For a wye-connected three-phase system the line voltage is higher than phase voltage by a factor of 1.732.

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True False

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Short Answer