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 test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)






2. both coils in this core are heavily insulated






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






4. Divergence of the magnetic field causes this






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






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






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






8. An electromagnetic device that operates on the principle of self induction. It uses AC.






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






10. Anything above 600 volts is _____?






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






12. 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






13. Central magnetic core made of






14. An instrument used to measure electrical current.






15. 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.






16. 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.






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






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






19. Transformer losses are classified as _____ and _____.






20. Provides the ratio between the applied primary voltage and the induced secondary voltage as result of the turns ratio






21. How coercivity is minimized






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






23. The 3 types of transformer power loss






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






25. 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






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






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






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






29. The 4 types of transformer cores






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






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






32. A choke coil uses this to induce current






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






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






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






36. The simplest type of transformer core






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






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






39. A simple design has a core within each coil






40. 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






41. The 3 principle components of a transformer






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






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






44. Used to increase the magnetic flux in a transformer






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






46. A designated limit of operating characteristics based on definite conditions.






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






48. 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.






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






50. 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.