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






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






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






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






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






6. Insulated primary and secondary coils are in close proximity to each other - no iron core and very innefficient






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






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






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






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






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






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






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






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






15. Transformer losses are classified as _____ and _____.






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






17. How coercivity is minimized






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






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






20. 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






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






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






23. An instrument used to measure electrical current.






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






25. Central magnetic core made of






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






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






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






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






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






31. The formula for the voltage related to turns ratio






32. The output side it develops AC by electromagnetic mutual induction - Secondary voltage is induced in this coil






33. Used to increase the magnetic flux in a transformer






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






35. 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.






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






37. 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)






38. 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.






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






40. 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.






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






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






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






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






45. Function of the dielectric oil






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






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






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






49. Anything above 600 volts is _____?






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






Can you answer 50 questions in 15 minutes?



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