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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. An instrument used to measure electrical current.






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






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






4. Copper loss is known as _____ loss.






5. A single electrical circuit.






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






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






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






9. 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






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






11. Is concentrated in the metal core






12. 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.






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






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






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






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






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






18. A choke coil uses this to induce current






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






20. Central magnetic core made of






21. 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






22. A transformer loses less than _% in energy






23. Used to increase the magnetic flux in a transformer






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






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






26. _____ currents are reduced by laminating the core.






27. 3 types of transformers






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






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






30. Function of the dielectric oil






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






32. The current related to turns ratio law






33. How coercivity is minimized






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






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






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






37. What does transformer efficiency mean?






38. The formula for the voltage related to turns ratio






39. What is a rotation meter?






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






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






42. 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.






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






44. The output which can be delivered for the time specified at rated secondary voltage and rated frequency without exceeding the specified temperature limitations.






45. Divergence of the magnetic field causes this






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






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






48. 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






49. The 4 types of transformer cores






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







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