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






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






3. A control power transformer...






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






5. 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?






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






7. 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...






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






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






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






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






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






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






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






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






16. 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?






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






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. Alternating current may be defined as...






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






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






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






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






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






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


26. 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?






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






28. 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?






29. Not a symptom of electrical shock?.






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






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






32. Not true about AC power?






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






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






35. 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?






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






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






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






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






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






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






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






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






45. 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?






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






47. Where should grounding resistors be located?






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






49. 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...






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