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. Used to increase the magnetic flux in a transformer






2. A part of a circuit made of a low melting point material so that it will melt and break the circuit when a specified current exceeded. Always the weakest point in the circuit.






3. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.






4. Function of the dielectric oil






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






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






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






8. Core losses are _____ loss and _____ - _____ loss.






9. The entire transformer is placed in a metal tank then immersed in ________.






10. The 3 principle components of a transformer






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






12. A choke coil uses this to induce current






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






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






15. A transformer loses less than _% in energy






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






17. A ___________ transformer is a continuously adjustable Autotransformer.






18. A magnetic field changing with respect to the conductor will generate a _____ in the conductor.






19. _____ currents are reduced by laminating the core.






20. It refers to the direction of current flow in a closed circuit.






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






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






23. Autotransformers are not safe when they supply a _____ voltage from a high voltage source.






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






25. To minimize ________ in transformer construction - the primary and secondary windings are placed on the same leg(s) of the core.






26. The formula for the voltage related to turns ratio






27. 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 _____.






28. The simplest type of transformer core






29. Divergence of the magnetic field causes this






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






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






32. How coercivity is minimized






33. _____ shows that the voltamperes of the primary of a transformer equal the voltamperes of the secondary of a transformer.






34. A large amount of power wasted with the open-ended core






35. Copper loss is known as _____ loss.






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






37. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.






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






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






40. What does transformer efficiency mean?






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






42. Central magnetic core made of






43. The current related to turns ratio law






44. The turns ratio between the windings (primary & secondary) of a transformer unless otherwise specified.






45. The total numbre of lines or force issuing from a pole. (north or south)






46. An abnormal connection of relative low resistance - whether made accidentally or intentionally - between two point of different potential in a circuit.






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






48. Transformers designed for 4800 volt primary operation - but the secondaries are connected 240/480 volts. Winding ratio is 10:1






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






50. Is concentrated in the metal core