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 a symptom of electrical shock?.






2. A control power transformer...






3. 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...






4. What is a capacitor?






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






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






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






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






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






10. 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...






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






12. 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?






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






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






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






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






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






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






19. 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?






20. 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...






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






22. 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.






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






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






26. 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?






27. Not true about AC power?






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






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






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






31. 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?






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






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






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






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






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






37. The standard frequency of power supplied by the power company is...






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






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






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






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






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






43. Where should grounding resistors be located?






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






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






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






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






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






49. 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?






50. A current transformer has a ratio of 350:5. If the phase current is 70 amperes - what would be the secondary current?