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






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






3. 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?






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






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






6. Not a symptom of electrical shock?.






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






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






9. 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...






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






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






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






13. 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?






14. 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.






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






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






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






18. Define alternating current...






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






20. Alternating current may be defined as...






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






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






23. 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.






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






25. What is the danger when working around capacitors?






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






27. How should clothing be removed from a burn?






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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






43. 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?






44. A control power transformer...






45. A solenoid coil is...






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






47. What steps up or steps down AC voltage?






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






49. 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...






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