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 ___________ transformer is a continuously adjustable Autotransformer.






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






3. 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






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






5. 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.






6. The simplest type of transformer core






7. Used to increase the magnetic flux in a transformer






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






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






10. 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 _____.






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






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






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






14. 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






15. Copper loss is known as _____ loss.






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






17. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.






18. The 3 types of transformer power loss






19. 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






20. Function of the dielectric oil






21. What is a rotation meter?






22. Modern; extremely efficient-more effective coupling between primary and secondary coils; smaller and lighter






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






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






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






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






27. 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






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






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






30. Anything above 600 volts is _____?






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






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






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






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






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






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






37. In a transformer the _____ current will always flow in such a direction that its magnetizing action will oppose the magnetizing action of the primary winding.






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






39. 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






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






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






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






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






44. 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.






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






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






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






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






49. 3 types of transformers






50. 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