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






2. 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 _____.






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






5. An instrument used to measure electrical current.






6. The 3 principle components of a transformer






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






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






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






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






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






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






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






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






15. What does transformer efficiency mean?






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






17. A transformer loses less than _% in energy






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






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






20. _____ currents are reduced by laminating the core.






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






22. The 4 types of transformer cores






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






25. A designated limit of operating characteristics based on definite conditions.






26. both coils in this core are heavily insulated






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






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






29. A part of a circuit made of a low melting point material so that it will melt and break the circuit when a specified current exceeded. Always the weakest point in the circuit.






30. Divergence of the magnetic field causes this






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






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






33. Function of the dielectric oil






34. 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.






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






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






37. Copper loss is known as _____ loss.






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






39. A choke coil uses this to induce current






40. A simple design has a core within each coil






41. 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






42. The formula for the current related to voltage law






43. The winding to which the load is connected is called the _____ winding.






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






45. 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






46. Is concentrated in the metal core






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






48. A transformer which when supplied from a constant potential source automatically maintans a constant current in its secondary circuit under varying conditions of load impedance. Used on series street light circuits.






49. Anything above 600 volts is _____?






50. Central magnetic core made of