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. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






4. 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.






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






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






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






8. A large amount of power wasted with the open-ended core






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






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






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






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






13. Copper loss is known as _____ loss.






14. Is concentrated in the metal core






15. Transformers with 4800 volt primaries and 120/240 volt secondaries - either pole or subway type - with two secondary windings terminating at internal links which provide for parallel operation of the secondary windings at 120 volts or series operatio






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






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






18. 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 _____.






19. A transformer rated at 500KVA and below used for voltage transformation on the distribuition system.






20. What does transformer efficiency mean?






21. The formula for the current related to voltage law






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






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






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






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






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






27. 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






28. 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.






29. Defined as the ratio of the power output to the power input (in a closed circuit containing resistance)






30. The 3 types of transformer power loss






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






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






33. 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






34. 3 types of transformers






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






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






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






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






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






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






41. Used to increase the magnetic flux in a transformer






42. A simple design has a core within each coil






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






44. 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






45. Central magnetic core made of






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






47. A single electrical circuit.






48. The relationship between current and voltage in the coils are inverse






49. both coils in this core are heavily insulated






50. The simplest type of transformer core