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






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






3. The primary leads of a single-phase transformer should be connected to the...






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






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






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






7. 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...






8. At what rate should mouth-to-mouth resuscitation be applied?






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






10. What steps up or steps down AC voltage?






11. 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?






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






13. The main function of CT's and PT's on a main substation is to...






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






15. What is a capacitor?






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






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






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






19. A control power transformer...






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






21. The combined capacitance of two capacitors in parallel is...






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






23. What is the danger when working around capacitors?






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






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






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






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






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






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






30. A transformer has 1 -600 turns in the primary and 400 turns in the secondary. The primary voltage is 2 -400 volts. What is the secondary voltage?






31. Alternating current may be defined as...






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






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






34. The following motor leads are brought out of a 3-phase motor (T1 - T2 - T3 - T4 - T5 - T6). This motor is probably for...






35. How can you tell if a victim receiving mouth-to-mouth resuscitation is getting air into the lungs?






36. 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?






37. High voltage is used to transmit power over long distances...






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






39. Define alternating current...






40. The current on the primary side of a step-down transformer with a 4:1 ratio will be...






41. The purpose of a zig-zag transformer is to...






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






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






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






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






46. If a voltmeter were placed between two phase leads of a three-phase 480-volt system - the meter would read...






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






48. 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...






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






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