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






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






3. A choke coil uses this to induce current






4. An instrument used to measure electrical current.






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






6. Is concentrated in the metal core






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






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






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






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






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






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






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






14. Central magnetic core made of






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






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






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






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






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






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






21. Transformer losses are classified as _____ and _____.






22. The 3 principle components of a transformer






23. How coercivity is minimized






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






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






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. 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.






29. 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 _____.






30. 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






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






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






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






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






35. The current related to turns ratio law






36. What does transformer efficiency mean?






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






38. The entire transformer is placed in a metal tank then immersed in ________.






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






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






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






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






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






44. 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






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






46. 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






47. _____ currents are reduced by laminating the core.






48. 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






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






50. Divergence of the magnetic field causes this







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