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 current related to turns ratio law






3. Connected to earth or to some conducting body which serves in place of the earth.






4. Modern; extremely efficient-more effective coupling between primary and secondary coils; smaller and lighter






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






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






7. 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.






8. What does transformer efficiency mean?






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






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






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






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






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






14. The simplest type of transformer core






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






16. A ___________ transformer is a continuously adjustable Autotransformer.






17. 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






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






19. The 3 principle components of a transformer






20. Determines if the transformer is a step up or step down transformer






21. 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.






22. 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.






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






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






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






26. How coils serve as the primary and secondary windings for an autotransformer






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






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






29. An instrument used to measure electrical current.






30. What is a rotation meter?






31. 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 _____.






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






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






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






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






36. A simple design has a core within each coil






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






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






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






40. 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.






41. Current flows through the primary winding in response to primary voltage and sets up a magnetic field that varies in direction and stregnth. under the influence of the changing magnetic field an AC voltage/kv is induced across the secondary coil by e






42. The shape of the core of the transformer ensures a ______________ for the magnetic flux with maximum concentration within the core and minimum leakage of the air






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






44. A magnet made by winding a coil of wire around a soft iron core. Current passed through this winding produces magnetic lines of force in the coil.






45. Central magnetic core made of






46. The formula for the voltage related to turns ratio






47. This type of core is moderately efficient due to closing the core and layering design which reduces power loss from less leakage flux which provides a continuous path for magnetic flux and an increase in field strength






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






49. 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






50. Two coils wound on a closed iron core form a ________.