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. 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?






2. What is the danger when working around capacitors?






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






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






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






6. 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?






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






8. A solenoid coil is...






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






10. 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...






11. How should clothing be removed from a burn?






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






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






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






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






16. 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.






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






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






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






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






21. A control power transformer...






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






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






24. 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?






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






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






27. 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?






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






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






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






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






32. What is the first step to be followed in aiding a victim of electrical shock?






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






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






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






36. Alternating current may be defined as...






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






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


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






40. 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.






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






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






43. 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?






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






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






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






47. 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?






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






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






50. When troubleshooting a circuit with a bank of capacitors - what precautions must be taken?