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






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






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






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






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






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






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






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






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






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






11. 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.






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






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






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






15. Define alternating current...






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






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






18. 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?






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






20. 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...






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






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






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






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






25. A solenoid coil is...






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






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






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






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






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






31. 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?






32. A control power transformer...






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






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






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






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






37. 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?






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






39. 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?






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






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






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






43. Not a symptom of electrical shock?.






44. 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?






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






46. 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...






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






48. 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.






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






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