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






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






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






4. Hysteresis Loss can be reduced by using a core with this feature






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






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






7. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.






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






9. 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






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






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






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






13. Anything above 600 volts is _____?






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






15. Copper loss is known as _____ loss.






16. A transformer is a device that either increases or decreases alternating current and voltage using this principle






17. 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 _____.






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






19. 3 types of transformers






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






21. Both the primary and secondary coils in a transformer are arranged around this






22. A single electrical circuit.






23. The formula for the current related to voltage law






24. A simple design has a core within each coil






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






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






27. 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.






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






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






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






31. Function of the dielectric oil






32. The formula for the voltage related to turns ratio






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






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






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






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






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






38. 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.






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






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






41. A transformer loses less than _% in energy






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






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






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






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






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






47. What does transformer efficiency mean?






48. The current related to turns ratio law






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






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