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 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






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






3. 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






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






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






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






7. Insulated primary and secondary coils are in close proximity to each other - no iron core and very innefficient






8. Used to increase the magnetic flux in a transformer






9. The transformer winding to which the load is connected is called the _____ winding.






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






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






12. A transformer loses less than _% in energy






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






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






15. 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.






16. The simplest type of transformer core






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






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






19. 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.






20. Central magnetic core made of






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






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






23. The 3 principle components of a transformer






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






25. How a variable degree of core saturation is accomplished in a saturable reactor?






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






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






28. The current related to turns ratio law






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






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






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






32. Is concentrated in the metal core






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






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






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






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






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






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






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






40. The 4 types of transformer cores






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






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






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






44. 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






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






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






47. The formula for the current related to voltage law






48. 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.






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






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