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






3. 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






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






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






6. Copper loss is known as _____ loss.






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






8. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.






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






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






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






12. 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






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






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






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






16. Anything above 600 volts is _____?






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






18. _____ currents are reduced by laminating the core.






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






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






21. The formula for the current related to voltage law






22. The output side it develops AC by electromagnetic mutual induction - Secondary voltage is induced in this coil






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






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






25. 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






26. The simplest type of transformer core






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






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






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






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






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






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






33. 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.






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






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






36. Divergence of the magnetic field causes this






37. The 4 types of transformer cores






38. A simple design has a core within each coil






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






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






41. 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.






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






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






44. 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






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






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






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






49. Central magnetic core made of






50. Insulated primary and secondary coils are in close proximity to each other - no iron core and very innefficient