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






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






3. 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)






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






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






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






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






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






9. 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






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






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






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






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






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






15. The simplest type of transformer core






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






17. 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.






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






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






20. A simple design has a core within each coil






21. The 3 types of transformer power loss






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






23. 3 types of transformers






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






25. An instrument used to measure electrical current.






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






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






28. Divergence of the magnetic field causes this






29. A transformer loses less than _% in energy






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






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






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






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






34. The relationship between amperage flowing through the coils and the number of turns on individual coils is inverse






35. The formula for the current related to voltage law






36. 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 _____.






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






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






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






41. A choke coil uses this to induce current






42. Copper loss is known as _____ loss.






43. The formula for the voltage related to turns ratio






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






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






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






47. Central magnetic core made of






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






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






50. What does transformer efficiency mean?