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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. The current related to turns ratio law






2. A single electrical circuit.






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






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






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






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






7. 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






8. 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.






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






10. The formula for the voltage related to turns ratio






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






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






13. Used to increase the magnetic flux in a transformer






14. How coercivity is minimized






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






17. Function of the dielectric oil






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






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






20. 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






21. Anything above 600 volts is _____?






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






23. 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






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






25. This is the most advanced and most efficient type of tansformer; it is commonly used in x-ray equipment






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






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






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






29. 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 _____.






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






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






32. 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.






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






34. Copper loss is known as _____ loss.






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






36. 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)






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






38. The formula for the current related to voltage law






39. Divergence of the magnetic field causes this






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






41. 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.






42. 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






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






44. An electromagnetic device that operates on the principle of self induction. It uses AC.






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






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






47. A stationary device for transferring alternating current electrical energy from one circuit to another circuit by electromagnetic means.






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






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






50. 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.







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