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. Copper loss is known as _____ loss.






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






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. A choke coil uses this to induce current






5. both coils in this core are heavily insulated






6. The turns ratio between the windings (primary & secondary) of a transformer unless otherwise specified.






7. A single electrical circuit.






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






9. The simplest type of transformer core






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






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






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






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






14. 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.






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






16. 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.






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






18. 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.






19. 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.






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






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






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






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






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






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






26. The characteristic that requires energy to carry out the constant reorientation of the magnetic dipoles in the hysteresis loss






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






28. 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






29. The formula for the current related to voltage law






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






31. 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






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






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






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






35. 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.






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






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






38. 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 _____.






39. Current flows through the primary winding in response to primary voltage and sets up a magnetic field that varies in direction and stregnth. under the influence of the changing magnetic field an AC voltage/kv is induced across the secondary coil by e






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






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






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






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






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






45. The 3 types of transformer power loss






46. Transformer losses are classified as _____ and _____.






47. 3 types of transformers






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






49. Central magnetic core made of






50. Function of the dielectric oil