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 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.






2. A single electrical circuit.






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






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






5. The simplest type of transformer core






6. 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.






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






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






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






10. 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






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






12. 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.






13. The formula for the current related to voltage law






14. A simple design has a core within each coil






15. Used to increase the magnetic flux in a transformer






16. _____ currents are reduced by laminating the core.






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






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






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






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






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






22. Anything above 600 volts is _____?






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






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






25. 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






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






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






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






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






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






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






32. A transformer loses less than _% in energy






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






34. The current related to turns ratio law






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






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






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






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






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






40. Is concentrated in the metal core






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






42. The 4 types of transformer cores






43. How coercivity is minimized






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






45. 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.






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






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






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






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






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