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






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






3. The 4 types of transformer cores






4. The formula for the current related to voltage law






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






6. 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 _____.






7. A part of a circuit made of a low melting point material so that it will melt and break the circuit when a specified current exceeded. Always the weakest point in the circuit.






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






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






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






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






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






13. both coils in this core are heavily insulated






14. The 3 types of transformer power loss






15. A test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)






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






17. An instrument used to measure electrical current.






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






19. What is a rotation meter?






20. 3 types of transformers






21. 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






22. 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






23. Kind of wire is the secondary coil in a transformer






24. _____ currents are reduced by laminating the core.






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






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






27. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






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






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






32. A transformer loses less than _% in energy






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






34. 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






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






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






37. 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.






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






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






40. 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.






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






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






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






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






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






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






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






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






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






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