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






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






3. 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 _____.






4. A simple design has a core within each coil






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






6. An instrument used to measure electrical current.






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






8. Anything above 600 volts is _____?






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






10. 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.






11. The formula for the current related to voltage law






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






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






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






15. 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.






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






17. both coils in this core are heavily insulated






18. _____ shows that the voltages across the windings of a transformer are directly proportional to the turns in each winding.






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






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






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






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






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






24. 3 types of transformers






25. _____ currents are reduced by laminating the core.






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






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






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






29. Copper loss is known as _____ loss.






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






31. 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.






32. 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






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






34. Central magnetic core made of






35. Divergence of the magnetic field causes this






36. 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






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






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






39. Used to increase the magnetic flux in a transformer






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






41. What does transformer efficiency mean?






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






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






44. The formula for the voltage related to turns ratio






45. The simplest type of transformer core






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






47. 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.






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






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. Function of the dielectric oil