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. 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






2. 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






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






4. A simple design has a core within each coil






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






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






7. What does transformer efficiency mean?






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






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






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






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






12. Copper loss is known as _____ loss.






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






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






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






16. The 3 principle components of a transformer






17. An instrument used to measure electrical current.






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






19. closed core with a top and bottom. It directs the magnetic field towards the primary and secondary coils and increases the field stregnth






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






21. 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






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






23. The formula for the current related to voltage law






24. The formula for the voltage related to turns ratio






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






26. both coils in this core are heavily insulated






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






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






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






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






31. 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.






32. The simplest type of transformer core






33. _____ currents are reduced by laminating the core.






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






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






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






37. Used to increase the magnetic flux in a transformer






38. The 4 types of transformer cores






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






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






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






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






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






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






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






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






47. For a step up and step down transformer if the turns ratio is constant this is the only way to change the output voltage






48. 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 _____.






49. The current related to turns ratio law






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