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






2. For a step up and step down transformer if the turns ratio is constant this is the only way to change the output voltage






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






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






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






6. The formula for the voltage related to turns ratio






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






8. _____ currents are reduced by laminating the core.






9. What does transformer efficiency mean?






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






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






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






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






14. Used to increase the magnetic flux in a transformer






15. A simple design has a core within each coil






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






17. How coercivity is minimized






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






19. Transformer losses are classified as _____ and _____.






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






21. 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.






22. 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)






23. What is a rotation meter?






24. Anything above 600 volts is _____?






25. The 3 principle components of a transformer






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






27. 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 _____.






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






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






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






31. 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






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






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






34. Divergence of the magnetic field causes this






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






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






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






38. 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.






39. 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






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






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






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






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






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






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






46. 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






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






48. 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






49. An instrument used to measure electrical current.






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