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






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






3. Function of the dielectric oil






4. The 3 types of transformer power loss






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






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






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






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






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






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






11. 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.






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






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






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






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






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






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






18. The 4 types of transformer cores






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






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






21. The current related to turns ratio law






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






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






24. A choke coil uses this to induce current






25. 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






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






27. 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






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






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






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






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






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






33. Anything above 600 volts is _____?






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






35. 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






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






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






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






39. Waste of power known as transformer loss - often produced by closed-ended core






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






41. _____ currents are reduced by laminating the core.






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






43. 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 _____.






44. 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.






45. A simple design has a core within each coil






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






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






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






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






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