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. How coercivity is minimized






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






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






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






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






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






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






8. Function of the dielectric oil






9. 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






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






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






12. _____ currents are reduced by laminating the core.






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






14. The 3 types of transformer power loss






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






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






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






18. Central magnetic core made of






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






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






21. The 4 types of transformer cores






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






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






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






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






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






27. 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.






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






29. Divergence of the magnetic field causes this






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






31. An instrument used to measure electrical current.






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






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






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






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






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






37. The transformer winding to which the load is connected is called the _____ winding.






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






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






40. A transformer loses less than _% in energy






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






42. A choke coil uses this to induce current






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






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






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






46. 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






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






48. Is concentrated in the metal core






49. 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






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