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






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






4. What is a rotation meter?






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






6. Is concentrated in the metal core






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






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






9. Transformer losses are classified as _____ and _____.






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






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






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






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






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






15. The current related to turns ratio law






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






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






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






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






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






21. 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.






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






23. _____ currents are reduced by laminating the core.






24. 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






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






26. 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 _____.






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






28. Central magnetic core made of






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






30. A transformer loses less than _% in energy






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






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






34. ___________ is often used in laminated cores - increases electrical resistance which decreases eddy currents






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






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






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






38. How coercivity is minimized






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






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






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






43. The 3 types of transformer power loss






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






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






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






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






48. The formula for the current related to voltage law






49. Copper loss is known as _____ loss.






50. 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.