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. Not true about AC power?






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






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






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






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






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






7. 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.






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






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






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






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






12. 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?






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






14. 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?






15. A solenoid coil is...






16. 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...






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






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






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






20. 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?






21. 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?






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






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






24. 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...






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






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






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






28. 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?






29. What steps up or steps down AC voltage?






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






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






32. 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?






33. 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?






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






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






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






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






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






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






40. 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...






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






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






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






44. 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.






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






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






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






48. Where should grounding resistors be located?






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






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