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 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.






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






3. 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.






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






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






6. 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






7. 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)






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






9. 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.






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






11. Is concentrated in the metal core






12. The turns of both windings are cut by the same flux; therefore the induced emf in each turn of both windings is the _____.






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






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






15. The formula for the current related to voltage law






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






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






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






19. Central magnetic core made of






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






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






22. The 3 types of transformer power loss






23. The simplest type of transformer core






24. What does transformer efficiency mean?






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






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






27. 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






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






29. What is a rotation meter?






30. 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.






31. Function of the dielectric oil






32. The 3 principle components of a transformer






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






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






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






36. A simple design has a core within each coil






37. The 4 types of transformer cores






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






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






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






41. The current related to turns ratio law






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






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






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






45. 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






46. Determines if the transformer is a step up or step down transformer






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






48. 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.






49. 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.






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