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






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






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






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






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






6. Central magnetic core made of






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






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






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






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






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






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






13. An instrument used to measure electrical current.






14. The formula for the voltage related to turns ratio






15. both coils in this core are heavily insulated






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






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






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






19. The 3 types of transformer power loss






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






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






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






23. 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






24. The 4 types of transformer cores






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






26. 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






27. 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






28. The simplest type of transformer core






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






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






31. How coercivity is minimized






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






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






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






35. 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.






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






37. The current related to turns ratio law






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






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






40. Transformer losses are classified as _____ and _____.






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






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






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






44. The terminals of the low voltage winding are marked _____.






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






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






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






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






49. 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






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