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. Transformer losses are classified as _____ and _____.






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






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






4. 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 _____.






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






6. 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.






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






8. 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.






9. A simple design has a core within each coil






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






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






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






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






14. The simplest type of transformer core






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






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






17. How the voltage and the number of turns are related for the voltage related to turn ratio






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






19. A transformer loses less than _% in energy






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






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






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






23. 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






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






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






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






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






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






29. 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






30. Central magnetic core made of






31. 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






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






33. Anything above 600 volts is _____?






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






35. Divergence of the magnetic field causes this






36. The 4 types of transformer cores






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






38. Function of the dielectric oil






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






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






41. _____ currents are reduced by laminating the core.






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






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






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






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






46. An instrument used to measure electrical current.






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






48. How coercivity is minimized






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






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