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






2. Function of the dielectric oil






3. The 3 principle components of a transformer






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






5. Copper loss is known as _____ loss.






6. 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






7. Transformer losses are classified as _____ and _____.






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






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






10. The 3 types of transformer power loss






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






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






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






14. both coils in this core are heavily insulated






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






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






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






18. _____ currents are reduced by laminating the core.






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






20. The formula for the voltage related to turns ratio






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






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






23. 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






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






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






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






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






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






29. 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.






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






31. 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.






32. The output which can be delivered for the time specified at rated secondary voltage and rated frequency without exceeding the specified temperature limitations.






33. An instrument used to measure electrical current.






34. A transformer loses less than _% in energy






35. A choke coil uses this to induce current






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






37. Divergence of the magnetic field causes this






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






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






40. 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.






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. Some losses occur in all transformers. These losses are classified as copper losses and _____ losses.






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






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






45. 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 _____.






46. The formula for the current related to voltage law






47. 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.






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






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






50. A simple design has a core within each coil