Test your basic knowledge |

Subjects : science, engineering
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. Which of the following is not needed when using an ohmmeter to determine if a motor is grounded?






2. The minimum allowable size for trailing cables for mobile haulage equipment powered by alternating current is...






3. A transformer with 1 -500 turns in the primary winding has a primary voltage of 2 -400 volts and a secondary voltage of 120 volts. How many turns are in the secondary winding?






4. If 2000 watts is read in the primary of a single-phase transformer - What is the wattage in the secondary? (Assuming no losses.)






5. If the conductors of a balanced - three-phase circuit pass through a current transformer - how many amps will flow in the transformer?






6. When not connected to a load - the secondary leads of a current transformer should be...






7. What happens to a motor that is connected to a three-phase cable when two of the cable's leads are reversed?






8. How do you change the direction of a 3-phase AC motor?






9. What type motor is a wound-rotor induction motor?






10. 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...






11. A current transformer has a ratio of 350:5. If the phase current is 70 amperes - what would be the secondary current?






12. A control power transformer...






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...






14. When connecting 3 single-phase transformers into a three-phase system - which of the following is NOT required for the single-phase transformers.






15. The speed of an alternating current - squirrel-cage induction motor is...






16. A transformer with 3000 turns in the primary winding has a primary voltage of 4 -800 volts and a secondary voltage of 240 volts. How many turns are in the secondary winding?






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

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18. A transformer has 2000 turns in the primary and 500 turns in the secondary. The primary voltage is 3 -200 volts. What is the secondary voltage?






19. Not a symptom of electrical shock?.






20. Alternating current may be defined as...






21. Why is 440-volt - three-phase power more commonly used in mining than 220-volt - three-phase power?






22. If 13 -200 volts are measured from phase-to-phase across a wye-connected secondary - What is the phase-to-ground voltage?






23. Current transformers - or CT's - are used to...






24. The standard frequency of power supplied by the power company is...






25. Operating coils - motors - transformers - relays and solenoids depend upon...






26. What is the danger when working around capacitors?






27. Surface transformer installations - unless constructed to eliminate shock hazards - must be installed at least...






28. If you use a clamp-on ammeter or tong tester around all three-phase wires of an energized three- phase circuit simultaneously...






29. Find the turns ratio of a single-phase transformer with the following values: Primary power of 10 KW - secondary current of 200 amps - and primary voltage of 250 volts.






30. Compared to the secondary of a loaded - step-down transformer - the primary has...






31. The size of a transformer is measured in...






32. Current that changes periodically in direction is...






33. What position of a selector switch using a voltmeter would you select to check a 120-volt AC circuit to obtain the most accurate reading?






34. Current in an AC circuit may be measured by...






35. 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?






36. If a voltmeter is connected between a phase lead and the ground of a three-phase 480-volt system - the meter will read...






37. If current were flowing through a grounding resistor in a 440-volt - resistance-grounded system - this would probably be because...






38. Should a ground fault occur - what device can be installed to limit the current in the neutral of a three-phase AC system?






39. What should the duty rating of a grounding resistor be?






40. Using a 10:1 ratio transformer - the terminals on the secondary side or lower voltage side would be marked...






41. The neutral ground-bed electrical power system of an underground mine should be separated from the lightning arrestor grounds by at least...






42. What is a capacitor?






43. A transformer with a 1:1 ratio is usually a (an)...






44. Which of the following does a squirrel cage induction motor have?






45. What type of 3-phase AC motor is used most often around a mine?






46. A wound-rotor induction motor has all the following EXCEPT...






47. The secondary windings on a 10:1 step-down transformer will have a wire size...






48. 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...






49. The transformer used only to measure voltage is a...






50. Not true about AC power?