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






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






3. 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.






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






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






6. 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






7. Determines if the transformer is a step up or step down transformer






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






9. Kind of wire is the secondary coil in a transformer






10. Transformer losses are classified as _____ and _____.






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






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






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






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






15. 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






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






18. An instrument used to measure electrical current.






19. 3 types of transformers






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






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






22. 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.






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






24. Is concentrated in the metal core






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






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






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






28. What is a rotation meter?






29. 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.






30. Modern; extremely efficient-more effective coupling between primary and secondary coils; smaller and lighter






31. Copper loss is known as _____ loss.






32. Central magnetic core made of






33. 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






34. The 3 types of transformer power loss






35. Divergence of the magnetic field causes this






36. 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






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






38. The 3 principle components of a transformer






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






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






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






42. A simple design has a core within each coil






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






44. A transformer rated at 500KVA and below used for voltage transformation on the distribuition system.






45. A transformer loses less than _% in energy






46. How coercivity is minimized






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






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






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






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