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1. To select a buck-and-boost transformer use ________.

charts provided by the manufacturer

standard electrical calculations

system measurements

tables listed in the NEC®

Question 1 of 20

2. In a potential transformer, the voltage across the secondary terminals is always lower than the primary voltage and is rated at ________.

120V

150V

100V

170V

Question 2 of 20

3. Which of the following is defined as the ratio of the peak value of a waveform to the rms value?

Crest factor

Frequency

Service factor

Eddy current

Question 3 of 20

4. Neutral overloading in a receptacle branch circuit may be detected by ________.

the load changing voltage across the circuit

a reading of more than 120V to the ungrounded conductor

a reading of more than 2V to ground

a reading of less than 2V to ground

Question 4 of 20

5. A step-down transformer is a type of ________.

specialty transformer that is primarily used for small work, such as doorbells and other signaling systems

transformer that is connected in series with the load

transformer that is considered a low kVA device

transformer that is usually connected to an electrical instrument, such as an ammeter, voltmeter, wattmeter, or relay

Question 5 of 20

6. Autotransformers are especially practical if the difference between the primary and secondary voltages is ________.

as great as possible

relatively small

relatively large

within 15% of factory specifications

Question 6 of 20

7. A device that is used to step up generated voltage to make it suitable for commercial transmission is called a ________.

grounding transformer

power transformer

current transformer

potential transformer

Question 7 of 20

8. If the resonant frequency is near the harmonic voltage, the resultant harmonic current can ________.

blow the capacitor fuses

increase the impedance

decrease the voltage

overheat the windings

Question 8 of 20

9. Which of the following systems is the most likely to be affected significantly by harmonics?

Three-phase, four-wire systems with no 120V loads

Three-phase, four-wire systems with nonlinear loads connected to 120V circuits

Single-phase, three-wire systems with some loads connected to 120V circuits

Three-phase, three-wire systems with no 120V loads

Question 9 of 20

10. Potential or voltage transformers are ________.

three-phase transformers

single-phase transformers

buck-and-boost transformer

control transformers

Question 10 of 20

11. Which of the following transformers is the most appropriate type of transformer to use for series street lighting?

Buck-and-boost transformer

Potential transformer

Constant-current transformer

Current transformer

Question 11 of 20

12. The frequency of the fourth harmonic is ________.

120

420

240

480

Question 12 of 20

13. Which of the following describes an autotransformer?

A transformer that has no electrical metallic connection between the primary and secondary windings

A transformer that is normally used with metering equipment when the line voltage is too high for the metering equipment

A transformer with two secondary windings that can deliver two secondary voltages

A transformer that uses a single winding for both its primary and secondary

Question 13 of 20

14. How many volts can a 1kVA buck-and-boost transformer actually carry in the secondary winding?

1kVA

11kVA

2.4kVA

24kVA

Question 14 of 20

15. In a step-down transformer with a 4.16kV primary delta connection and a 480/277V wye secondary, the transformer turns ratio is ________.

15:1

5:1

11:1

9:1

Question 15 of 20

16. Which of the following refers to the total load seen by the CT secondary?

Burden

Current

Potential

Duty

Question 16 of 20

17. The instantaneous direction of current at a specific moment is known as ________.

polarity

impedance

internal resistance

hysteresis

Question 17 of 20

18. A residence with 120V and 240V loads is likely to be served by a(n) ________.

single-phase transformer with two secondaries

buck-and-boost transformer

autotransformer

three-phase transformer

Question 18 of 20

19. 15. The line voltages in a Y connection are ________.

1.732 times higher than the phase voltages

1.812 times higher than the phase voltages

the same as the phase voltages

lower than the phase voltages

Question 19 of 20

20. The secondary current in a constant-current transformer is typically between ________.

1A and 2A

10A and 20A

4A and 7.5A

0.5 and 1A

Question 20 of 20

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