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. The formula for the voltage related to turns ratio






3. 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.






4. A transformer loses less than _% in energy






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






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






7. Central magnetic core made of






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






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






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






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






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






13. Hysteresis Loss can be reduced by using a core with this feature






14. 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.






15. A ___________ transformer is a continuously adjustable Autotransformer.






16. Divergence of the magnetic field causes this






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






18. Provides the ratio between the applied primary voltage and the induced secondary voltage as result of the turns ratio






19. Used to increase the magnetic flux in a transformer






20. 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






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






22. Copper loss is known as _____ loss.






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






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






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






26. Function of the dielectric oil






27. 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






28. The 3 types of transformer power loss






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






30. 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






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






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






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






34. Modern; extremely efficient-more effective coupling between primary and secondary coils; smaller and lighter






35. 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)






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






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






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






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






40. How coercivity is minimized






41. The formula for the current related to voltage law






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






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






44. The 4 types of transformer cores






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






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






47. Is concentrated in the metal core






48. A single electrical circuit.






49. 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 _____.






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