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






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






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






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






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






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






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






8. In a transformer the _____ current will always flow in such a direction that its magnetizing action will oppose the magnetizing action of the primary winding.






9. _____ currents are reduced by laminating the core.






10. The formula for the current related to voltage law






11. 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






12. What does transformer efficiency mean?






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






14. Anything above 600 volts is _____?






15. The current related to turns ratio law






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






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






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






19. A transformer loses less than _% in energy






20. 3 types of transformers






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






22. Transformer losses are classified as _____ and _____.






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






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






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






26. 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






27. A simple design has a core within each coil






28. 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






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






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






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






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






33. 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






34. A system of conductors in which at least one conductors or point (usually the middle wire or neutral point of a transformer or generator windings) is intentionally grounded either solididly or through a current-limiting device.






35. 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.






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






37. Central magnetic core made of






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






39. 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.






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






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






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






43. The winding of a transformer to which electrical energy is supplied.






44. Function of the dielectric oil






45. The simplest type of transformer core






46. When an alternating current is applied to the high-voltage (H) winding of a transformer with no load on the secondary (X) winding - a small current - called the _____ current - flows in the primary.






47. How coercivity is minimized






48. A ___________ transformer is a continuously adjustable Autotransformer.






49. The 4 types of transformer cores






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