Test your basic knowledge |

Transformers

Subject : 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. closed core with a top and bottom. It directs the magnetic field towards the primary and secondary coils and increases the field stregnth






2. The terminals of the high voltage winding are marked _____.






3. Both the primary and secondary coils in a transformer are arranged around this






4. If the transformer is used as a _____ transformer - the high voltage winding is the primary.






5. If the transformer is used as a _____ transformer - the low voltage winding is the primary.






6. Hysteresis Loss can be reduced by using a core with this feature






7. The 3 principle components of a transformer






8. The winding to which the load is connected is called the _____ winding.






9. The voltage induced in the coil is directly proportional to this






10. _____ shows that the voltages across the windings of a transformer are directly proportional to the turns in each winding.






11. A transformer primary (H) that has 400 turns is wound to step the voltage down from 240 volts to 120 volts. The number or turns (TX) required in the secondary (X) winding is _____.






12. Some losses occur in all transformers. These losses are classified as copper losses and _____ losses.






13. Instrument transformers reduce high voltages and currents to safe - usable values for the operation of _____ equipment.






14. The 4 types of transformer cores






15. Instrument transformers reduce high voltages and currents to safe - usable values for the operation of _____ _____.






16. has a laminated iron core (layers of metal plates)






17. 3 types of transformers






18. Function of the dielectric oil






19. A transformer is a device that either increases or decreases alternating current and voltage using this principle






20. The characteristic that requires energy to carry out the constant reorientation of the magnetic dipoles in the hysteresis loss






21. Used to increase the magnetic flux in a transformer






22. The relationship between current and voltage in the coils are inverse






23. A partial or total local failure in the insulation or continuity of a conductor.






24. The output rating of a transformer is based upon the maximum _____ the transformer is capable of carrying without exceeding a certain temperature rise.






25. This type of transformer power loss is caused by the continually changing AC current movement which constantly magnetizes/demagnetizes/re-magnetizes






26. both coils in this core are heavily insulated






27. Waste of power known as transformer loss - often produced by closed-ended core






28. ___________ is often used in laminated cores - increases electrical resistance which decreases eddy currents






29. Refers to the transformer's ability to avoid power loss (heat)






30. How the voltage and the number of turns are related for the voltage related to turn ratio






31. Provides the ratio between the applied primary voltage and the induced secondary voltage as result of the turns ratio






32. The simplest type of transformer core






33. The winding of a transformer to which electrical energy is supplied.






34. The energy is always transferred without a change in frequency - but usually with changes in _____ and _____.






35. Divergence of the magnetic field causes this






36. A choke coil uses this to induce current






37. The magnetic lines of force that flow from the north pole of a magnet and return to the south pole.






38. A designated limit of operating characteristics based on definite conditions.






39. A system of conductors in which at least one conductors or point (usually the middle wire or neutral point of a transformer or generator windings) is intentionally grounded either solididly or through a current-limiting device.






40. The 3 types of transformer power loss






41. The number of turns can be adjusted in these types of transformers






42. This core is more efficient than the air core because the iron core in each coil intensifies the magnetic flux in both primary and secondary coils when they become magnetized as current flows through each set of coils






43. A stationary device for transferring alternating current electrical energy from one circuit to another circuit by electromagnetic means.






44. To prevent injury to personnel when servicing any equipment connected to a current transformer - the secondary winding must be ____ - _____.






45. Copper loss is known as _____ loss.






46. What does transformer efficiency mean?






47. A transformer which when supplied from a constant potential source automatically maintans a constant current in its secondary circuit under varying conditions of load impedance. Used on series street light circuits.






48. The transformer winding to which voltage is supplied is called the _____ winding.






49. A simple design has a core within each coil






50. The relationship between amperage flowing through the coils and the number of turns on individual coils is inverse