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






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






4. The 3 types of transformer power loss






5. The formula for the voltage related to turns ratio






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






7. 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.






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






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






10. 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.






11. 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 _____.






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






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






14. A system of conductors in which at least one conductors or point (usually the middle wire or neutral point of a transformer or generator windings) is intentionally grounded either solididly or through a current-limiting device.






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






16. What does transformer efficiency mean?






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






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






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






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






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






22. 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






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






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






25. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






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






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






30. The 4 types of transformer cores






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






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






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






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






35. The simplest type of transformer core






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






37. Transformer losses are classified as _____ and _____.






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






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






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






41. 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.






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






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






44. What is a rotation meter?






45. Function of the dielectric oil






46. A choke coil uses this to induce current






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






48. How coercivity is minimized






49. 3 types of transformers






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