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






2. How coils serve as the primary and secondary windings for an autotransformer






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






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






5. Autotransformers are not safe when they supply a _____ voltage from a high voltage source.






6. 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.






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






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






9. It refers to the direction of current flow in a closed circuit.






10. both coils in this core are heavily insulated






11. Used to increase the magnetic flux in a transformer






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






13. 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 _____.






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






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






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






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






18. Copper loss is known as _____ loss.






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






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






21. What is a rotation meter?






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






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






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






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






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






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






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






29. 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






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






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






32. Is concentrated in the metal core






33. 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






34. 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.






35. A single electrical circuit.






36. The 3 types of transformer power loss






37. 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.






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






39. A ___________ transformer is a continuously adjustable Autotransformer.






40. Anything above 600 volts is _____?






41. A transformer loses less than _% in energy






42. The simplest type of transformer core






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






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






45. A simple design has a core within each coil






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






47. The formula for the current related to voltage law






48. The current related to turns ratio law






49. How coercivity is minimized






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







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