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






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






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






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






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






6. 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






7. What is a rotation meter?






8. 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






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






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






11. Function of the dielectric oil






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






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






14. The 4 types of transformer cores






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






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






17. 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






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






19. Copper loss is known as _____ loss.






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






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






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






23. 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






24. Used to increase the magnetic flux in a transformer






25. 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.






26. What does transformer efficiency mean?






27. The formula for the current related to voltage law






28. Transformer losses are classified as _____ and _____.






29. A choke coil uses this to induce current






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






31. 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






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






33. 3 types of transformers






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






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






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






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






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






39. Central magnetic core made of






40. A stationary device for transferring alternating current electrical energy from one circuit to another circuit by electromagnetic means.






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






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






43. A transformer loses less than _% in energy






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






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






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






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






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






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






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