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. Divergence of the magnetic field causes this






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






3. The formula for the voltage related to turns ratio






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






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






6. 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






7. A simple design has a core within each coil






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






9. Is concentrated in the metal core






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






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






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






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






14. closed core with a top and bottom. It directs the magnetic field towards the primary and secondary coils and increases the field stregnth






15. Used to increase the magnetic flux in a transformer






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






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






18. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






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






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






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






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






25. 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






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






27. 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)






28. Transformer losses are classified as _____ and _____.






29. The 4 types of transformer cores






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






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






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






34. 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






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






36. A transformer loses less than _% in energy






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






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






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






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






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






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






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






44. The simplest type of transformer core






45. The formula for the current related to voltage law






46. 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






47. The 3 principle components of a transformer






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






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






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