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






2. Used to increase the magnetic flux in a transformer






3. 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.






4. Anything above 600 volts is _____?






5. 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






6. 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.






7. 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






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






9. Some losses occur in all transformers. These losses are classified as copper losses and _____ losses.






10. The 3 principle components of a transformer






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






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






13. 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.






14. Transformer losses are classified as _____ and _____.






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






16. The capacity of a transformer is rated in ____ _____.






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






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






19. 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






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






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






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






23. 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 _____.






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






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






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






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






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






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






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






31. An instrument used to measure electrical current.






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






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






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






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






36. 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.






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






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






39. 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.






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






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






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






43. The 3 types of transformer power loss






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






45. Connected to earth or to some conducting body which serves in place of the earth.






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






47. 3 types of transformers






48. A partial or total local failure in the insulation or continuity of a conductor.






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






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