Test your basic knowledge |

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






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






3. A transformer loses less than _% in energy






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






5. The 3 types of transformer power loss






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






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






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






9. 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.






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






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






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






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






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






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






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






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






18. A ___________ transformer is a continuously adjustable Autotransformer.






19. Anything above 600 volts is _____?






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






21. An instrument used to measure electrical current.






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






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






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






25. The terminals of the low voltage winding are marked _____.






26. Function of the dielectric oil






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






28. What is a rotation meter?






29. _____ currents are reduced by laminating the core.






30. A single electrical circuit.






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






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






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






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






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






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






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






38. 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






39. 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






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






41. What does transformer efficiency mean?






42. 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 _____.






43. Is concentrated in the metal core






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






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






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






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






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






49. 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.






50. If the transformer is used as a _____ transformer - the low voltage winding is the primary.