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 terminals of the high voltage winding are marked _____.






2. 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






3. 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






4. The 4 types of transformer cores






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






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






7. The 3 types of transformer power loss






8. 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.






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






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






11. With no load on the secondary winding - a small current flows in the primary called _____ _____.






12. A single electrical circuit.






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






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






15. The current flowing through the primary winding - in response to the applied primary voltage - sets this up






16. A choke coil uses this to induce current






17. The input side that attaches to the AC supply it recieves the electrical energy or incoming voltage






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






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






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






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






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






23. Is concentrated in the metal core






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






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






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






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






28. The simplest type of transformer core






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






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






31. The output side it develops AC by electromagnetic mutual induction - Secondary voltage is induced in this coil






32. When an alternating current is applied to the high-voltage (H) winding of a transformer with no load on the secondary (X) winding - a small current - called the _____ current - flows in the primary.






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






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






35. both coils in this core are heavily insulated






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






37. A ___________ transformer is a continuously adjustable Autotransformer.






38. 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






39. The formula for the current related to voltage law






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






41. The current related to turns ratio law






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






43. 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






44. 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.






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






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






47. 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






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






49. 3 types of transformers






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