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 relationship between current and voltage in the coils are inverse






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






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






4. The simplest type of transformer core






5. A transformer loses less than _% in energy






6. 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






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






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






9. 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






10. A choke coil uses this to induce current






11. The formula for the voltage related to turns ratio






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






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






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






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






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






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






18. The formula for the current related to voltage law






19. Is concentrated in the metal core






20. How coils serve as the primary and secondary windings for an autotransformer






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






22. 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






23. _____ currents are reduced by laminating the core.






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






25. 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.






26. The 4 types of transformer cores






27. 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.






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






29. 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






30. 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.






31. The 3 types of transformer power loss






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






33. A simple design has a core within each coil






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






35. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.






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






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






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






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






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






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






42. How coercivity is minimized






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






44. 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






45. An instrument used to measure electrical current.






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






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






48. Divergence of the magnetic field causes this






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






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