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






2. 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?






3. Where should grounding resistors be located?






4. The load to which the secondary winding of a current transformer was connected has opened. The secondary leads should be...






5. How should clothing be removed from a burn?






6. 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?






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






8. AC voltage is raised or lowered by means of...






9. Not an acceptable method for the installations of surface transformers?






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






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


12. Not true about AC power?






13. 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...






14. Not a symptom of electrical shock?.






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






16. What is the danger when working around capacitors?






17. 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.






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






19. If any two-phase wires are reversed on a three-phase motor - the motor will...






20. The property of an electric circuit that opposes any change in current is called...






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






22. 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?






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






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






25. Alternating current may be defined as...






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






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






28. Three-phase AC underground cables must be provided with overcurrent protection using a...






29. Define alternating current...






30. 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?






31. A transformer has a primary voltage of 2 -800 volts and a secondary reading of 140 volts. If there are 2000 turns on the primary - how many turns are on the secondary?






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






33. A burn causing a blister is classified as a...






34. 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...






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






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






37. A transformer with 10 turns on the primary coil and 100 turns on the secondary is classified as...






38. The property of an electrical circuit that opposes any change in voltage is called...






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






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






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






42. What is a capacitor?






43. All transformers step voltage up or down by...






44. To protect against over-current in a three-phase circuit over-current protection must be provided for...






45. The primary function of a power transformer is to provide...






46. 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...






47. Which of the following is not needed when using an ohmmeter to determine if a motor is grounded?






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






49. The standard frequency of alternating current used at a mine is...






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