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. Used to increase the magnetic flux in a transformer






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






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






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






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






6. 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






7. An instrument used to measure electrical current.






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






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






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






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






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






13. A simple design has a core within each coil






14. The current related to turns ratio law






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






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






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






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






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






20. A choke coil uses this to induce current






21. Modern; used to control filament circuit; replaced both the rheostat and choke coil; operated on the electromagnetic principle that if an iron core within or near a coil is saturated with magnetic flux by an independed source of direct current - the






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






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






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






25. has a laminated iron core (layers of metal plates)






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






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






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






29. _____ shows that the voltamperes of the primary of a transformer equal the voltamperes of the secondary of a transformer.






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






31. 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.






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






33. Transformer losses are classified as _____ and _____.






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






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






37. What does transformer efficiency mean?






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






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






40. Anything above 600 volts is _____?






41. A single electrical circuit.






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






43. Copper loss is known as _____ loss.






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






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






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






47. both coils in this core are heavily insulated






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






49. 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 _____.






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