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






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






3. What is a capacitor?






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


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






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






7. Alternating current may be defined as...






8. Define alternating current...






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






10. Where should grounding resistors be located?






11. Not true about AC power?






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






13. How should clothing be removed from a burn?






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






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






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






17. 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?






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






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






20. What steps up or steps down AC voltage?






21. 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?






22. 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...






23. 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?






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






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






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






27. 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?






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






29. 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.






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






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






32. 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...






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






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






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






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






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






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






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






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






41. What is the danger when working around capacitors?






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






43. 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...






44. A solenoid coil is...






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






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






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






48. 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?






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






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