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 voltage induced in the coil is directly proportional to this






2. The 3 principle components of a transformer






3. 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.






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






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






6. The current related to turns ratio law






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






8. What is a rotation meter?






9. The energy is always transferred without a change in frequency - but usually with changes in _____ and _____.






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






11. A single electrical circuit.






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






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






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






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






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






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






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






19. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






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






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






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






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






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






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






28. 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






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






30. What does transformer efficiency mean?






31. 3 types of transformers






32. 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 _____.






33. Transformer losses are classified as _____ and _____.






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






35. A choke coil uses this to induce current






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






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






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






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






40. Is concentrated in the metal core






41. Transformers designed for 4800 volt primary operation - but the secondaries are connected 240/480 volts. Winding ratio is 10:1






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






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






44. The 3 types of transformer power loss






45. How coercivity is minimized






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. When an alternating current is applied to the high-voltage (H) winding of a transformer with no load on the secondary (X) winding - a small current - called the _____ current - flows in the primary.






48. To minimize ________ in transformer construction - the primary and secondary windings are placed on the same leg(s) of the core.






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






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