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






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






3. What steps up or steps down AC voltage?






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






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






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






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






8. Where should grounding resistors be located?






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






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






12. What is a capacitor?






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






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






15. Define alternating current...






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






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






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






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






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






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






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


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






24. Alternating current may be defined as...






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






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






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






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






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






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






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






32. 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?






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






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






35. 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?






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






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






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






39. 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?






40. 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...






41. How should clothing be removed from a burn?






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






43. 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...






44. A solenoid coil is...






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






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






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






48. 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.






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






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