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. An instrument used to measure electrical current.






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. A single electrical circuit.






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






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






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






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






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






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






10. 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






11. 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






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






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






14. A simple design has a core within each coil






15. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.






16. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






19. 3 types of transformers






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






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






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






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






24. Divergence of the magnetic field causes this






25. 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.






26. Function of the dielectric oil






27. Transformer losses are classified as _____ and _____.






28. Modern; used to control filament circuit; replaced both the rheostat and choke coil; operated on the electromagnetic principle that if an iron core within or near a coil is saturated with magnetic flux by an independed source of direct current - the






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






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






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






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






33. 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






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






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






36. 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.






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






38. A choke coil uses this to induce current






39. The 4 types of transformer cores






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






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






42. What is a rotation meter?






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






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






45. 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 _____.






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






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






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






49. _____ currents are reduced by laminating the core.






50. The 3 principle components of a transformer