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






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






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






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






5. 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






6. 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.






7. 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






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






9. Used to increase the magnetic flux in a transformer






10. This is the most advanced and most efficient type of tansformer; it is commonly used in x-ray equipment






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






12. The terminals of the low voltage winding are marked _____.






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






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






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






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






17. 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.






18. 3 types of transformers






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






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






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






22. A simple design has a core within each coil






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






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






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






26. Anything above 600 volts is _____?






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. What does transformer efficiency mean?






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






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






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






33. The formula for the voltage related to turns ratio






34. Function of the dielectric oil






35. The output which can be delivered for the time specified at rated secondary voltage and rated frequency without exceeding the specified temperature limitations.






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






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






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






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






40. 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.






41. 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.






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






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






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






45. A single electrical circuit.






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






47. _____ currents are reduced by laminating the core.






48. The formula for the current related to voltage law






49. A transformer loses less than _% in energy






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