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 large amount of power wasted with the open-ended core






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






3. 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.






4. 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.






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






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






7. Used to increase the magnetic flux in a transformer






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






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






10. The 3 types of transformer power loss






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






12. The current related to turns ratio law






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






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






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






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






17. 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






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






19. The simplest type of transformer core






20. How a variable degree of core saturation is accomplished in a saturable reactor?






21. Copper loss is known as _____ loss.






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






23. The characteristic that requires energy to carry out the constant reorientation of the magnetic dipoles in the hysteresis loss






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






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






26. 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






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






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






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






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






31. A single electrical circuit.






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






33. 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






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






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






36. 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






37. The formula for the voltage related to turns ratio






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






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






40. How coercivity is minimized






41. What does transformer efficiency mean?






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






43. Function of the dielectric oil






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






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






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






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






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






49. Divergence of the magnetic field causes this






50. The 3 principle components of a transformer