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






2. 3 types of transformers






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






4. The simplest type of transformer core






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






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






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






8. 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






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






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






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






12. both coils in this core are heavily insulated






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






14. A transformer loses less than _% in energy






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






16. Copper loss is known as _____ loss.






17. Function of the dielectric oil






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






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






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






21. _____ currents are reduced by laminating the core.






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






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






24. The 3 types of transformer power loss






25. The formula for the current related to voltage law






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






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






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






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






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






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






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






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






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






36. Central magnetic core made of






37. 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.






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






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






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






41. 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






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






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






44. What is a rotation meter?






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






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






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






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






49. An instrument used to measure electrical current.






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