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. Kind of wire is the secondary coil in a transformer






2. 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 _____.






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






4. It refers to the direction of current flow in a closed circuit.






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






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






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






8. How a variable degree of core saturation is accomplished in a saturable reactor?






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






10. An instrument used to measure electrical current.






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






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






13. A transformer loses less than _% in energy






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






15. 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.






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






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






18. Used to increase the magnetic flux in a transformer






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






20. A choke coil uses this to induce current






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






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






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






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






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






26. Anything above 600 volts is _____?






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






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






29. _____ currents are reduced by laminating the core.






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






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






32. 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






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






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






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






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






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






38. Is concentrated in the metal core






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






40. 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)






41. What does transformer efficiency mean?






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






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






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






45. The current related to turns ratio law






46. The voltage induced in the coil is directly proportional to this






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






48. 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






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






50. The formula for the voltage related to turns ratio