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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. 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.






2. A test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)






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






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






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






6. Anything above 600 volts is _____?






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






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






9. Transformer losses are classified as _____ and _____.






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






11. The 3 types of transformer power loss






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






13. An instrument used to measure electrical current.






14. The formula for the current related to voltage law






15. 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






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






17. Used to increase the magnetic flux in a transformer






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






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






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






21. 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.






22. A single electrical circuit.






23. The 3 principle components of a transformer






24. This core is more efficient than the air core because the iron core in each coil intensifies the magnetic flux in both primary and secondary coils when they become magnetized as current flows through each set of coils






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






26. 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.






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






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






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






30. 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.






31. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.






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






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






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






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






36. The current related to turns ratio law






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






38. 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.






39. The formula for the voltage related to turns ratio






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






41. 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 _____.






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






43. Function of the dielectric oil






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






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






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






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






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






49. What is a rotation meter?






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







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