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Transformers

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes. 2 minutes extra for reading the instructions.
  • 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. Both the primary and secondary coils in a transformer are arranged around this






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






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






4. Copper loss is known as _____ loss.






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






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






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






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






9. 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






10. The terminals of the low voltage winding are marked _____.






11. 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






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






13. The current related to turns ratio law






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






15. 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






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






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






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






19. 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.






20. Function of the dielectric oil






21. 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.






22. For a step up and step down transformer if the turns ratio is constant this is the only way to change the output voltage






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






24. An instrument used to measure electrical current.






25. Central magnetic core made of






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






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






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






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






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






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






32. Divergence of the magnetic field causes this






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






34. What is a rotation meter?






35. The 3 types of transformer power 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. Transformer losses are classified as _____ and _____.






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






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






40. The entire transformer is placed in a metal tank then immersed in ________.






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






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






43. The 3 principle components of a transformer






44. The simplest type of transformer core






45. 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






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






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






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






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






50. A single electrical circuit.






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