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






2. What does transformer efficiency mean?






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






4. A transformer loses less than _% in energy






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






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






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






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






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






10. 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.






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






12. The simplest type of transformer core






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






14. Is concentrated in the metal core






15. Function of the dielectric oil






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






17. 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.






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






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






20. What is a rotation meter?






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






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






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






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






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






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






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






28. 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)






29. The 4 types of transformer cores






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






31. Anything above 600 volts is _____?






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






33. 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






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






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






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






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






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






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






40. 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






41. 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






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






44. How coercivity is minimized






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






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






47. The transformer winding to which voltage is supplied is called the _____ winding.






48. The formula for the current related to voltage law






49. Used to increase the magnetic flux in a transformer






50. _____ currents are reduced by laminating the core.