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. 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.






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






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






4. 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?






5. 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...






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






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


9. Alternating current may be defined as...






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






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






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






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






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






16. What steps up or steps down AC voltage?






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






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






19. 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?






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






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






22. 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...






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






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






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






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






27. Define alternating current...






28. A control power transformer...






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






30. 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?






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






32. 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?






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






34. What is the danger when working around capacitors?






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






36. How should clothing be removed from a burn?






37. 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...






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






39. 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.






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






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






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






43. Not a symptom of electrical shock?.






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






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






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






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






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






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






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