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






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






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






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






5. What does transformer efficiency mean?






6. Copper loss is known as _____ loss.






7. 3 types of transformers






8. The 4 types of transformer cores






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






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






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






12. Function of the dielectric oil






13. A simple design has a core within each coil






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






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






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






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






18. 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.






19. 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.






20. Central magnetic core made of






21. _____ currents are reduced by laminating the core.






22. The 3 types of transformer power loss






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






24. 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






25. A choke coil uses this to induce current






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






27. Autotransformers are not safe when they supply a _____ voltage from a high voltage source.






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






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






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






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






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






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






34. What is a rotation meter?






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






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






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






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






39. 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






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






41. both coils in this core are heavily insulated






42. 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.






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






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






45. 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 _____.






46. 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






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






48. 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






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






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