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






2. 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






3. The 4 types of transformer cores






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






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






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






7. 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






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






9. Anything above 600 volts is _____?






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






11. _____ currents are reduced by laminating the core.






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






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






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






15. The output which can be delivered for the time specified at rated secondary voltage and rated frequency without exceeding the specified temperature limitations.






16. The simplest type of transformer core






17. The number of turns can be adjusted in these types of transformers






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






19. Transformer losses are classified as _____ and _____.






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






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






22. The loss of power required to reverse the core magnatism each time the current reverses. This loss is caused by friction between the molecules of iron as these particles are aligned first in one direction and the in the opposite direct as current dir






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






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






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






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






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






28. What does transformer efficiency mean?






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






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






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






32. 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.






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






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






35. Divergence of the magnetic field causes this






36. The current related to turns ratio law






37. 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 _____.






38. The 3 types of transformer power loss






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






40. The formula for the current related to voltage law






41. What is a rotation meter?






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






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






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






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






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






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






48. Is concentrated in the metal core






49. 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






50. A ___________ transformer is a continuously adjustable Autotransformer.