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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 formula for the current related to voltage law






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






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






4. Copper loss is known as _____ loss.






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






6. To minimize ________ in transformer construction - the primary and secondary windings are placed on the same leg(s) of the core.






7. What is a rotation meter?






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






9. 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






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






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






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






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






14. Central magnetic core made of






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






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






17. 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.






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






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






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






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






22. 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






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






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






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






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






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






28. A simple design has a core within each coil






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






30. The formula for the voltage related to turns ratio






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






32. 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.






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






34. 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






35. The 4 types of transformer cores






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






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






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






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






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






42. _____ currents are reduced by laminating the core.






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






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






45. 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






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






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






48. A designated limit of operating characteristics based on definite conditions.






49. The input side that attaches to the AC supply it recieves the electrical energy or incoming voltage






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







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