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






2. A transformer loses less than _% in energy






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






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






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






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






7. Function of the dielectric oil






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






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






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






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






12. Central magnetic core made of






13. 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.






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






15. 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.






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






17. A transformer primary (H) that has 400 turns is wound to step the voltage down from 240 volts to 120 volts. The number or turns (TX) required in the secondary (X) winding is _____.






18. An instrument used to measure electrical current.






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






20. 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






21. Is concentrated in the metal core






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






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






24. How the voltage and the number of turns are related for the voltage related to turn ratio






25. What is a rotation meter?






26. 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.






27. How coercivity is minimized






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






29. both coils in this core are heavily insulated






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






31. 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






32. Used to increase the magnetic flux in a transformer






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






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






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






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






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






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






39. _____ currents are reduced by laminating the core.






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






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






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






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






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






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






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






47. A ___________ transformer is a continuously adjustable Autotransformer.






48. The formula for the current related to voltage law






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






50. Refers to the transformer's ability to avoid power loss (heat)