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 with a 1:1 ratio is usually a (an)...






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






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






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






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






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






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






8. Not a symptom of electrical shock?.






9. 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...






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






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






12. How should clothing be removed from a burn?






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






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






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






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






17. 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...






18. 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...






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






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






21. What is a capacitor?






22. What steps up or steps down AC voltage?






23. Define alternating current...






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






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






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






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






28. The main function of CT's and PT's on a main substation is to...






29. A transformer has 1 -600 turns in the primary and 400 turns in the secondary. The primary voltage is 2 -400 volts. What is the secondary voltage?






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






31. 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?






32. 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?






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






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






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






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






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






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






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






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


41. 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?






42. A control power transformer...






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






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






45. A transformer with 10 turns on the primary coil and 100 turns on the secondary is classified as...






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






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






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






49. 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?






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