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






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






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






4. 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






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






6. The formula for the current related to voltage law






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






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






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






10. 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 _____.






11. Function of the dielectric oil






12. A single electrical circuit.






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






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






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






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






17. Transformer losses are classified as _____ and _____.






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






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






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






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






22. 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






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






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






25. A transformer loses less than _% in energy






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






27. A part of a circuit made of a low melting point material so that it will melt and break the circuit when a specified current exceeded. Always the weakest point in the circuit.






28. Copper loss is known as _____ loss.






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






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






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






32. The 4 types of transformer cores






33. A simple design has a core within each coil






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






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






36. The current related to turns ratio law






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






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






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






40. 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.






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






42. 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






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






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






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






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






47. An instrument used to measure electrical current.






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






49. Anything above 600 volts is _____?






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