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






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






4. 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?






5. A solenoid coil is...






6. Define alternating current...






7. 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.






8. 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?






9. 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...






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






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






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






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






14. 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?






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






16. Where should grounding resistors be located?






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






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






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






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






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






22. What steps up or steps down AC voltage?






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






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






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






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






27. Not a symptom of electrical shock?.






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






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






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






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






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






33. What is a capacitor?






34. 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?






35. 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?






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






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






38. A control power transformer...






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






40. 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...






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






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






43. Alternating current may be defined as...






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






45. A wound-rotor induction motor has all the following EXCEPT...






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






47. 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...






48. Not true about AC power?






49. 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...






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