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 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






2. 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.






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






4. A single electrical circuit.






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






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






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






8. The simplest type of transformer core






9. What is a rotation meter?






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






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






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






13. 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.






14. Transformer losses are classified as _____ and _____.






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






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






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






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






19. The 4 types of transformer cores






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






22. An instrument used to measure electrical current.






23. Is concentrated in the metal core






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






25. How coercivity is minimized






26. 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.






27. _____ currents are reduced by laminating the core.






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






29. The formula for the voltage related to turns ratio






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






32. A transformer loses less than _% in energy






33. 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






34. Transformers with 4800 volt primaries and 120/240 volt secondaries - either pole or subway type - with two secondary windings terminating at internal links which provide for parallel operation of the secondary windings at 120 volts or series operatio






35. If the transformer is used as a _____ transformer - the high voltage winding is the primary.






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






37. Function of the dielectric oil






38. 3 types of transformers






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






40. 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.






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






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






43. 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 _____.






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






45. 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.






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






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






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






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






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