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






2. The capacity of a transformer is rated in ____ _____.






3. The loss of power required to reverse the core magnatism each time the current reverses. This loss is caused by friction between the molecules of iron as these particles are aligned first in one direction and the in the opposite direct as current dir






4. The 3 principle components of a transformer






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






6. The 4 types of transformer cores






7. The turns of both windings are cut by the same flux; therefore the induced emf in each turn of both windings is the _____.






8. The formula for the voltage related to turns ratio






9. 3 types of transformers






10. Copper loss is known as _____ loss.






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






12. The formula for the current related to voltage law






13. An electromagnetic device that operates on the principle of self induction. It uses AC.






14. Transformers with 4800 volt primaries and 120/240 volt secondaries - either pole or subway type - with two secondary windings terminating at internal links which provide for parallel operation of the secondary windings at 120 volts or series operatio






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






16. An instrument used to measure electrical current.






17. Modern; used to control filament circuit; replaced both the rheostat and choke coil; operated on the electromagnetic principle that if an iron core within or near a coil is saturated with magnetic flux by an independed source of direct current - the






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






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






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






21. What does transformer efficiency mean?






22. A transformer rated at 500KVA and below used for voltage transformation on the distribuition system.






23. Reference to a jumper or conductor - to or from a piece of electrical equipment.






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






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






26. Central magnetic core made of






27. Anything above 600 volts is _____?






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






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






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






31. The current related to turns ratio law






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






33. In a transformer the _____ current will always flow in such a direction that its magnetizing action will oppose the magnetizing action of the primary winding.






34. 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 _____.






35. A transformer loses less than _% in energy






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






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






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






39. both coils in this core are heavily insulated






40. What is a rotation meter?






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






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






43. Kind of wire is the secondary coil in a transformer






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






45. Defined as the ratio of the power output to the power input (in a closed circuit containing resistance)






46. _____ currents are reduced by laminating the core.






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






48. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.






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






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