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 relationship between current and voltage in the coils are inverse






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






3. 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






4. Central magnetic core made of






5. What does transformer efficiency mean?






6. 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






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






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






9. A transformer which when supplied from a constant potential source automatically maintans a constant current in its secondary circuit under varying conditions of load impedance. Used on series street light circuits.






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






11. both coils in this core are heavily insulated






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






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






14. _____ currents are reduced by laminating the core.






15. A single electrical circuit.






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






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






18. 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






19. 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






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






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






22. An instrument used to measure electrical current.






23. Kind of wire is the secondary coil in a transformer






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






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






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






27. 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.






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






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






30. Copper loss is known as _____ loss.






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






32. 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)






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






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






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






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






37. Provides the ratio between the applied primary voltage and the induced secondary voltage as result of the turns ratio






38. 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 _____.






39. 3 types of transformers






40. 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.






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






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






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






44. The terminals of the high voltage winding are marked _____.






45. A ___________ transformer is a continuously adjustable Autotransformer.






46. The formula for the voltage related to turns ratio






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






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






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






50. Function of the dielectric oil