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






3. 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.






4. What does transformer efficiency mean?






5. The current related to turns ratio law






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






7. Copper loss is known as _____ loss.






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






9. An instrument used to measure electrical current.






10. A system of conductors in which at least one conductors or point (usually the middle wire or neutral point of a transformer or generator windings) is intentionally grounded either solididly or through a current-limiting device.






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






12. 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






13. 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






14. How coercivity is minimized






15. The winding of a transformer to which electrical energy is supplied.






16. 3 types of transformers






17. Central magnetic core made of






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






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






20. 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






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






22. Function of the dielectric oil






23. In a transformer the _____ current will always flow in such a direction that its magnetizing action will oppose the magnetizing action of the primary winding.






24. 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






25. The 3 types of transformer power loss






26. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.






27. 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.






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






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






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






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






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






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






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






35. This type of core is moderately efficient due to closing the core and layering design which reduces power loss from less leakage flux which provides a continuous path for magnetic flux and an increase in field strength






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






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






38. Used to increase the magnetic flux in a transformer






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






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






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






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






43. 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






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






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






46. The output rating of a transformer is based upon the maximum _____ the transformer is capable of carrying without exceeding a certain temperature rise.






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






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






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






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