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






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






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






4. 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.






5. The simplest type of transformer core






6. The 3 principle components of a transformer






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






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






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






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






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






12. 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






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






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






15. Function of the dielectric oil






16. If the transformer is used as a _____ transformer - the high voltage winding is the primary.






17. 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 _____.






18. Used to increase the magnetic flux in a transformer






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






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






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






22. A transformer is a device that either increases or decreases alternating current and voltage using this principle






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






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






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






26. A transformer loses less than _% in energy






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






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






29. Divergence of the magnetic field causes this






30. What does transformer efficiency mean?






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






32. Anything above 600 volts is _____?






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






34. A single electrical circuit.






35. Defined as the ratio of the power output to the power input (in a closed circuit containing resistance)






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






37. The 3 types of transformer power loss






38. A choke coil uses this to induce current






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






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






41. The formula for the current related to voltage law






42. 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.






43. 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.






44. Central magnetic core made of






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






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






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






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






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






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