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






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






3. The simplest type of transformer core






4. Function of the dielectric oil






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






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






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






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






9. Divergence of the magnetic field causes this






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






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






12. 3 types of transformers






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






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






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






16. 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






17. How coils serve as the primary and secondary windings for an autotransformer






18. Anything above 600 volts is _____?






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






20. An electromagnetic device that operates on the principle of self induction. It uses AC.






21. An instrument used to measure electrical current.






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






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






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






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






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






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






28. Is concentrated in the metal core






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






30. 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






31. What is a rotation meter?






32. Transformer losses are classified as _____ and _____.






33. 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.






34. 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






35. 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.






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






37. 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






38. both coils in this core are heavily insulated






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






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






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






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






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






44. 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






45. 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.






46. Copper loss is known as _____ loss.






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






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






49. The formula for the voltage related to turns ratio






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