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






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






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






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






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






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






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






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






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






10. 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...






11. 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?






12. What steps up or steps down AC voltage?






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






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






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






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






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






18. A control power transformer...






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


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






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






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






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






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






25. Not a symptom of electrical shock?.






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






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






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






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






30. Where should grounding resistors be located?






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






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






33. 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...






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






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






36. 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.






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






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






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






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






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






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






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






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






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






46. What is a capacitor?






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






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






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






50. A solenoid coil is...