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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. 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?






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






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






4. 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.






5. What is the danger when working around capacitors?






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






7. 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?






8. 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?






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






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






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






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






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






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






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






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






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






18. Alternating current may be defined as...






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






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






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






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






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






24. Not true about AC power?






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


26. What is a capacitor?






27. 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?






28. 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...






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






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






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






32. How should clothing be removed from a burn?






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






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






35. 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...






36. 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?






37. 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...






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






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






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






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






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






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






44. 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?






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






46. 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...






47. A solenoid coil is...






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






49. 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?






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






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