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






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






3. The formula for the current related to voltage law






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






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






6. A large amount of power wasted with the open-ended core






7. Function of the dielectric oil






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






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






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






11. 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.






12. A single electrical circuit.






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






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






15. Anything above 600 volts is _____?






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






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






18. 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.






19. Is concentrated in the metal core






20. 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.






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






22. Transformer losses are classified as _____ and _____.






23. 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.






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






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






26. A ___________ transformer is a continuously adjustable Autotransformer.






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






28. What does transformer efficiency mean?






29. A choke coil uses this to induce current






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






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






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. 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






34. 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






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






36. The entire transformer is placed in a metal tank then immersed in ________.






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






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






39. How coercivity is minimized






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






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






42. Divergence of the magnetic field causes this






43. Used to increase the magnetic flux in a transformer






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






45. 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






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






47. 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.






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






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






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