Test your basic knowledge |

AC Theory

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. The purpose of a zig-zag transformer is to...
480 volts.
Derive a neutral for grounding purposes.
Grounded phase and ground fault devices were not operating.
Hyperventilation.

2. A transformer has a primary voltage of 2 -400 volts and a secondary reading of 120 volts. If there are 1 -500 turns on the primary - how many turns are on the secondary?
60 Hertz
75 turns.
Circuit Breaker.
The current will read zero.

3. If 13 -200 volts are measured from phase-to-phase across a wye-connected secondary - What is the phase-to-ground voltage?
Lower current and higher voltage
7 -630 volts.
150 turns.
Provides single-phase power to smaller loads such as lights - heaters - etc.

4. The current on the primary side of a step-down transformer with a 4:1 ratio will be...
Current that changes constantly in magnitude and periodically in direction.
Four times less than that of the secondary.
Electro-magnetism for their operation.
60 cycles per second (60 Hertz).

5. What is the danger when working around capacitors?
The sum of the two capacitors.
Four times less than that of the secondary.
It provides good speed control.
An electrical shock hazard may exist.

6. The main function of CT's and PT's on a main substation is to...
Check to make sure that the victim is not still in contact with the electricity.
Allow for metering voltage and Current.
The capacitors should be discharged.
The chest should rise or inflate.

7. A 3-phase - 2 speed - constant torque motor is running at fast speed. The motor windings are connected wye for fast speed. Motor leads T4 - T5 and T6 are connected to the line leads. Motor leads T1 - T2 and T3 should be...
Two speeds
Tied together
3 -979 Volts.
A step-up transformer.

8. Compared to the secondary of a loaded - step-down transformer - the primary has...
Isolation transformer.
Lower current and higher voltage.
An electrical shock hazard may exist.
5:1.

9. The secondary windings on a 10:1 step-down transformer will have a wire size...
Hyperventilation.
At the source transformer.
Larger than that found in the primary winding.
277 volts.

10. What steps up or steps down AC voltage?
Full-load - three-phase voltage.
Transformer
It provides good speed control.
200 volts AC.

11. What type motor is a wound-rotor induction motor?
A.C.
Nearly constant.
Reverse its rotation.
The motor rotation is reversed.

12. To protect against over-current in a three-phase circuit over-current protection must be provided for...
At least two phases
Continuous.
Derive a neutral for grounding purposes.
Draw less current.

13. Two 10-hp induction motors are operating on 460 volts AC. One motor is connected by single- phase; the other is connected in three-phase. The three-phase will...
Draw less current.
Nearly constant.
Carotid pulse - which is located in the neck next to the Adam's apple.
12 to 15 times a minute.

14. Compared to the secondary of a loaded - step-down transformer - the primary has...
Disconnect the frame-grounding conductor.
Lower current and higher voltage
150 turns.
60 Hertz

15. A solenoid coil is...
At least two phases
An electromagnet.
Squirrel-cage induction motor.
It provides good speed control.

16. Alternating current may be defined as...
Current that changes constantly in magnitude and periodically in direction.
Carotid pulse - which is located in the neck next to the Adam's apple.
Provides single-phase power to smaller loads such as lights - heaters - etc.
X.

17. The primary leads of a single-phase transformer should be connected to the...
75 turns.
60 Hertz
H terminals.
Allow for metering voltage and Current.

18. Three-phase AC underground cables must be provided with overcurrent protection using a...
Capacitance.
A.C.
600 volts.
Circuit Breaker.

19. High voltage is used to transmit power over long distances...
Because less current flowing at high voltage causes less line loss per kilowatt.
2000 watts
12 to 15 times a minute.
The chest should rise or inflate.

20. The neutral ground-bed electrical power system of an underground mine should be separated from the lightning arrestor grounds by at least...
100 turns.
Derive a neutral for grounding purposes.
Current that changes constantly in magnitude and periodically in direction.
25 feet.

21. The transformer used only to measure voltage is a...
Four times less than that of the secondary.
Potential transformer.
Alternating current.
Full-load - three-phase voltage.

22. Define alternating current...
A step-up transformer.
Check to make sure that the victim is not still in contact with the electricity.
Current changing constantly in magnitude and periodically in direction.
The current will read zero.

23. When not connected to a load - the secondary leads of a current transformer should be...
Shunted and taped
Continuous.
3 -979 Volts.
Inductance.

24. When troubleshooting a circuit with a bank of capacitors - what precautions must be taken?
Full-load - three-phase voltage.
An electrical shock hazard may exist.
60 Hertz
The capacitors should be discharged.

25. Current transformers - or CT's - are used to...
Reverse its rotation.
Reduce high AC current to lower values and provide isolation between high voltage circuits and metering.
A.C.
Reverse any two-phase leads.

26. Where should grounding resistors be located?
At least two phases
Because 440-volt power draws less current so cables and control circuit wiring can be smaller.
At the source transformer.
Short-circuited after power has been removed.

27. What is a capacitor?
Capacitance.
A.C.
A device used to store electrical energy.
At least two phases

28. What type of 3-phase AC motor is used most often around a mine?
At the source transformer.
The capacitors should be discharged.
Current changing constantly in magnitude and periodically in direction.
Squirrel-cage induction motor.

29. 460 volts AC is required to operate two motors - one connected in single-phase and the other connected in three-phase. The three-phase motor will...
25 feet.
Transformers.
Draw less current.
Inductance.

30. The speed of an alternating current - squirrel-cage induction motor is...
Because less current flowing at high voltage causes less line loss per kilowatt.
Current changing constantly in magnitude and periodically in direction.
Allow for metering voltage and Current.
Nearly constant.

31. The property of an electric circuit that opposes any change in current is called...
Inductance.
5:1
Shunted and taped
Disconnect the frame-grounding conductor.

32. Surface transformer installations - unless constructed to eliminate shock hazards - must be installed at least...
15 feet off the ground.
Kilovolt ampere (KVA).
2000 watts
25 feet.

33. What value of voltage will be measured from phase-to-phase - in a wye-connected secondary - if 2 -300 volts is measured from phase-to-ground?
The motor rotation is reversed.
Kilovolt ampere (KVA).
3 -979 Volts.
200 volts AC.

34. Find the turns ratio of a single-phase transformer with the following values: Primary power of 5KW - secondary current of 100 amps - and primary voltage of 250 volts.
Reverse any two-phase leads.
Grounded phase and ground fault devices were not operating.
5:1
The sum of the two capacitors.

35. The primary function of a power transformer is to provide...
Zero amps.
An electrical shock hazard may exist.
Allow for metering voltage and Current.
Full-load - three-phase voltage.

36. The size of a transformer is measured in...
150 turns.
Kilovolt ampere (KVA).
Reverse its rotation.
Capacitance.

37. The most reliable method to use to determine whether or not the heart has stopped is by checking the...

38. Current in an AC circuit may be measured by...
No.6 AWG.
Clamp-on ammeter.
Inductance.
Squirrel-cage rotor.

39. A control power transformer...
An electromagnet.
Provides single-phase power to smaller loads such as lights - heaters - etc.
Reduce high AC current to lower values and provide isolation between high voltage circuits and metering.
Squirrel-cage induction motor.

40. The minimum allowable size for trailing cables for mobile haulage equipment powered by alternating current is...
12 to 15 times a minute.
No.6 AWG.
The chest should rise or inflate.
A device used to store electrical energy.

41. How should clothing be removed from a burn?
Electro-magnetism for their operation.
A grounding resistor.
X.
Cut around clothing that has adhered to the burned area.

42. Not true about AC power?
It provides good speed control.
Short-circuited after power has been removed.
H terminals.
Capacitance.

43. Not a symptom of electrical shock?.
Hyperventilation.
Electro-magnetism for their operation.
The motor rotation is reversed.
At the source transformer.

44. The combined capacitance of two capacitors in parallel is...
Lower current and higher voltage.
The sum of the two capacitors.
Electro-magnetism for their operation.
100 turns.

45. A wound-rotor induction motor has all the following EXCEPT...
5:1
Second-degree burn.
Squirrel-cage rotor.
Zero amps.

46. The standard frequency of alternating current used at a mine is...
60 Hertz
Nearly constant.
Lower current and higher voltage.
Reduce high AC current to lower values and provide isolation between high voltage circuits and metering.

47. Which of the following does a squirrel cage induction motor have?
Draw less current.
Stator windings.
3 -979 Volts.
Reverse any two-phase leads.

48. If a voltmeter were placed between two phase leads of a three-phase 480-volt system - the meter would read...
Full-load - three-phase voltage.
A step-up transformer.
480 volts.
Reverse any two-phase leads.

49. The load to which the secondary winding of a current transformer was connected has opened. The secondary leads should be...
600 volts.
Short-circuited after power has been removed.
Second-degree burn.
100 volts.

50. All transformers step voltage up or down by...
Inductance.
Lower current and higher voltage.
Check to make sure that the victim is not still in contact with the electricity.
A grounding resistor.

?:?:)

Search BasicVersity Tests

Browse BasicVersity

3d Computer Modeling
Study | Quiz | Subjects: it-skills, multimedia | Questions: 150+
Actionscript
Study | Quiz | Subjects: it-skills, multimedia | Questions: 10+
Adobe Flash
Study | Quiz | Subjects: it-skills, multimedia, flash | Questions: 50+
Adobe Illustrator
Study | Quiz | Subjects: it-skills, multimedia | Questions: 100+
Adobe Illustrator Shortcuts
Study | Quiz | Subject: it-skills | Questions: 50+
Adobe Indesign Publishing
Study | Quiz | Subject: it-skills | Questions: 150+
Adobe Photoshop CS 2 - CS 3
Study | Quiz | Subject: it-skills | Questions: 70+
Adobe Photoshop CS 5
Study | Quiz | Subject: it-skills | Questions: 140+
Adobe Photoshop CS 5 Keyboard Shortcuts
Study | Quiz | Subject: it-skills | Questions: 170+
Adobe Photoshop Graphic Design
Study | Quiz | Subject: it-skills | Questions: 100+
Adobe Photoshop Tools And Commands
Study | Quiz | Subject: it-skills | Questions: 110+
Adobe Premiere Keyboard Shortcuts
Study | Quiz | Subject: it-skills | Questions: 50+
Adobe Premiere Pro
Study | Quiz | Subject: it-skills | Questions: 50+
After Effects Keyboard Shortcuts
Study | Quiz | Subject: it-skills | Questions: 170+
Agile Development
Study | Quiz | Subject: it-skills | Questions: 50+
Agile Scrum Methodology
Study | Quiz | Subject: it-skills | Questions: 10+
Ajax
Study | Quiz | Subject: it-skills | Questions: 30+
Android Programming
Study | Quiz | Subject: it-skills | Questions: 130+
Animation
Study | Quiz | Subject: it-skills | Questions: 60+
Asp.net Programming
Study | Quiz | Subject: it-skills | Questions: 100+

1 of 109 pages [Next] [Last Page]

Test your basic knowledge |

AC Theory

?:?:)

Search BasicVersity Tests

Browse BasicVersity

3d Computer Modeling

Actionscript

Adobe Flash

Adobe Illustrator

Adobe Illustrator Shortcuts

Adobe Indesign Publishing

Adobe Photoshop CS 2 - CS 3

Adobe Photoshop CS 5

Adobe Photoshop CS 5 Keyboard Shortcuts

Adobe Photoshop Graphic Design

Adobe Photoshop Tools And Commands

Adobe Premiere Keyboard Shortcuts

Adobe Premiere Pro

After Effects Keyboard Shortcuts

Agile Development

Agile Scrum Methodology

Ajax

Android Programming

Animation

Asp.net Programming