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






2. What is a capacitor?






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






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






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






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






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






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






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






10. What steps up or steps down AC voltage?






11. 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?






12. 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?






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






14. Define alternating current...






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






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






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






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






19. 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?






20. 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...






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






22. A solenoid coil is...






23. Where should grounding resistors be located?






24. 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?






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






26. Not a symptom of electrical shock?.






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






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


29. 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.






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






31. A control power transformer...






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






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






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






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






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






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






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






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






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






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






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






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






46. What is the danger when working around capacitors?






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






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






49. 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...






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