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 -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?






2. Where should grounding resistors be located?






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






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






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






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






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






8. 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.






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






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






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






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






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






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






15. 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?






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






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






18. 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?






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






20. 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...






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






22. What is a capacitor?






23. Under fault conditions - the grounding resistor in a high voltage circuit limits the voltage drop in the grounding circuit external to the resistor to not more than...






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






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






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






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






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






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






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






31. Not true about AC power?






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






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






34. 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?






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






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






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






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






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






40. A control power transformer...






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






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






43. A solenoid coil is...






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


45. What is the danger when working around capacitors?






46. Alternating current may be defined as...






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






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






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






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