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






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






3. 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.






4. 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.






5. The formula for the current related to voltage law






6. 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.






7. How coercivity is minimized






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






9. Transformer losses are classified as _____ and _____.






10. The simplest type of transformer core






11. A choke coil uses this to induce current






12. 3 types of transformers






13. The current related to turns ratio law






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






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






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






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






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






19. The 4 types of transformer cores






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






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






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






23. 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.






24. Used to increase the magnetic flux in a transformer






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






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






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






28. To minimize ________ in transformer construction - the primary and secondary windings are placed on the same leg(s) of the core.






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






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






31. 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






32. The turns of both windings are cut by the same flux; therefore the induced emf in each turn of both windings is the _____.






33. 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






34. Reference to a jumper or conductor - to or from a piece of electrical equipment.






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






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






37. _____ currents are reduced by laminating the core.






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






39. A test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)






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






41. Anything above 600 volts is _____?






42. Is concentrated in the metal core






43. 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 _____.






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






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






46. An electromagnetic device that operates on the principle of self induction. It uses AC.






47. 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






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






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






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