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. Waste of power known as transformer loss - often produced by closed-ended core






2. The current related to turns ratio law






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






4. 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.






5. Divergence of the magnetic field causes this






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






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






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






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






11. 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






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






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






14. For a step up and step down transformer if the turns ratio is constant this is the only way to change the output voltage






15. A ___________ transformer is a continuously adjustable Autotransformer.






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






17. 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.






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






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






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






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






22. What does transformer efficiency mean?






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






24. 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






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






26. The simplest type of transformer core






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






28. The relationship between current and voltage in the coils are inverse






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






30. The 3 types of transformer power loss






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






32. A transformer loses less than _% in energy






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






34. Copper loss is known as _____ loss.






35. The formula for the voltage related to turns ratio






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






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






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






39. 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.






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






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






42. Is concentrated in the metal core






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






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






45. The 4 types of transformer cores






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






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






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






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






50. 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.