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 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






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






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






4. Is concentrated in the metal core






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






6. Copper loss is known as _____ loss.






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






8. An instrument used to measure electrical current.






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






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






11. A single electrical circuit.






12. The current related to turns ratio law






13. Transformer losses are classified as _____ and _____.






14. Function of the dielectric oil






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






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






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






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






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






20. Divergence of the magnetic field causes this






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






22. How coercivity is minimized






23. 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






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






25. The 3 types of transformer power loss






26. both coils in this core are heavily insulated






27. The simplest type of transformer core






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






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






30. A transformer loses less than _% in energy






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






32. 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






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






34. 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






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






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






37. 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






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






39. _____ currents are reduced by laminating the core.






40. 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)






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






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






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






44. 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






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






46. 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.






47. The capacity of a transformer is rated in ____ _____.






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






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






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