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 speed of an alternating current - squirrel-cage induction motor is...






2. 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...






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






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






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






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






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






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






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






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






11. 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.






12. 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...






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






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






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






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






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






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






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






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






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






22. 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?






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






24. What steps up or steps down AC voltage?






25. 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?






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






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






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






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






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






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






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






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






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






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






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






37. Not true about AC power?






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






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






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






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


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






43. Which of the following is not needed when using an ohmmeter to determine if a motor is grounded?






44. What is the danger when working around capacitors?






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






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






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






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






49. Not a symptom of electrical shock?.






50. 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?