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






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






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






4. 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 _____.






5. The simplest type of transformer core






6. A choke coil uses this to induce current






7. The 3 types of transformer power loss






8. A transformer loses less than _% in energy






9. Is concentrated in the metal core






10. To prevent injury to personnel when servicing any equipment connected to a current transformer - the secondary winding must be ____ - _____.






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






12. 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.






13. 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






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






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






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






17. Central magnetic core made of






18. Used to increase the magnetic flux in a transformer






19. _____ currents are reduced by laminating the core.






20. 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.






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






22. The output rating of a transformer is based upon the maximum _____ the transformer is capable of carrying without exceeding a certain temperature rise.






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






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






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






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






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






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






29. Copper loss is known as _____ loss.






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






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






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






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






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






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






36. 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






37. What is a rotation meter?






38. The current related to turns ratio law






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






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






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






42. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






45. A single electrical circuit.






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






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






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






49. How coercivity is minimized






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