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






2. 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...






3. 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?






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






5. Not a symptom of electrical shock?.






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






7. At what rate should mouth-to-mouth resuscitation be applied?






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






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






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






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






12. 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.






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






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






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






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






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






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






19. 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...






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






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






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






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






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






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






26. Where should grounding resistors be located?






27. How should clothing be removed from a burn?






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






29. 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...






30. What is a capacitor?






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






32. 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?






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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






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