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. Kind of wire is the secondary coil in a transformer






2. A choke coil uses this to induce current






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






4. Copper loss is known as _____ loss.






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






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






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






8. It refers to the direction of current flow in a closed circuit.






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






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






11. A single electrical circuit.






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






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






14. How coils serve as the primary and secondary windings for an autotransformer






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






16. 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






17. The winding of a transformer to which electrical energy is supplied.






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






19. 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 _____.






20. How coercivity is minimized






21. 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.






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






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






24. The 3 principle components of a transformer






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






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






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






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






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






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






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






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






33. What does transformer efficiency mean?






34. A ___________ transformer is a continuously adjustable Autotransformer.






35. The simplest type of transformer core






36. 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






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






38. Anything above 600 volts is _____?






39. This core is more efficient than the air core because the iron core in each coil intensifies the magnetic flux in both primary and secondary coils when they become magnetized as current flows through each set of coils






40. The relationship between current and voltage in the coils are inverse






41. A simple design has a core within each coil






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






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






44. 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.






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






46. Both the primary and secondary coils in a transformer are arranged around this






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






49. 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.






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