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 3 types of transformer power loss






2. A single electrical circuit.






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






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






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






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






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






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






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






10. both coils in this core are heavily insulated






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






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






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






14. 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






15. The number of turns can be adjusted in these types of transformers






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






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






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






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






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






21. Function of the dielectric oil






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






23. 3 types of transformers






24. Transformers with 4800 volt primaries and 120/240 volt secondaries - either pole or subway type - with two secondary windings terminating at internal links which provide for parallel operation of the secondary windings at 120 volts or series operatio






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






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






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






28. _____ currents are reduced by laminating the core.






29. 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






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






31. A test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)






32. The formula for the current related to voltage law






33. The shape of the core of the transformer ensures a ______________ for the magnetic flux with maximum concentration within the core and minimum leakage of the air






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






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






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






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






38. A transformer loses less than _% in energy






39. 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.






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






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






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






43. 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






44. The 4 types of transformer cores






45. Central magnetic core made of






46. 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.






47. A simple design has a core within each coil






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






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






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