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






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






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






4. A transformer loses less than _% in energy






5. Is concentrated in the metal core






6. A ___________ transformer is a continuously adjustable Autotransformer.






7. What is a rotation meter?






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






9. Central magnetic core made of






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






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






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






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






14. 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.






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






16. 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






17. A single electrical circuit.






18. The formula for the voltage related to turns ratio






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






20. 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.






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






22. What does transformer efficiency mean?






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






24. Core losses are _____ loss and _____ - _____ loss.






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






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






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






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






29. 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






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






31. 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.






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






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






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






35. Function of the dielectric oil






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






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






38. The winding to which the load is connected is called the _____ winding.






39. 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)






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






41. Insulated primary and secondary coils are in close proximity to each other - no iron core and very innefficient






42. A choke coil uses this to induce current






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






44. The 3 principle components of a transformer






45. 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






46. 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






47. Copper loss is known as _____ loss.






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






49. How coercivity is minimized






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