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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. 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.






2. Central magnetic core made of






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






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






5. 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






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






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






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






9. The current related to turns ratio law






10. Anything above 600 volts is _____?






11. _____ currents are reduced by laminating the core.






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






13. 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.






14. Divergence of the magnetic field causes this






15. 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






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






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






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






19. The relationship between amperage flowing through the coils and the number of turns on individual coils is inverse






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






21. The 3 types of transformer power loss






22. Function of the dielectric oil






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






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






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






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






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






28. 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






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






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






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






32. 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






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






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






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






36. 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






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






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






39. What does transformer efficiency mean?






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






41. Transformer losses are classified as _____ and _____.






42. A ___________ transformer is a continuously adjustable Autotransformer.






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






44. With no load on the secondary winding - a small current flows in the primary called _____ _____.






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






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






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






48. The simplest type of transformer core






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






50. How coercivity is minimized






Can you answer 50 questions in 15 minutes?



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