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. Alternating current may be defined as...






2. 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...






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






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






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






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






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






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






9. How should clothing be removed from a burn?






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






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






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






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






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






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






17. Define alternating current...






18. 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?






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






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






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






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






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






24. A control power transformer...






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






26. 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.






27. 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...






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






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






30. 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.






31. What is the danger when working around capacitors?






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






33. Not a symptom of electrical shock?.






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






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






36. What is a capacitor?






37. 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...






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






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






40. A solenoid coil is...






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






42. 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?






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






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






45. 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?






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






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






48. 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?






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






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