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. How coercivity is minimized






2. 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 _____.






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






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






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






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






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






8. 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.






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






10. Modern; used to control filament circuit; replaced both the rheostat and choke coil; operated on the electromagnetic principle that if an iron core within or near a coil is saturated with magnetic flux by an independed source of direct current - the






11. 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)






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






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






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






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






16. The 3 principle components of a transformer






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






18. 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.






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






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






21. A choke coil uses this to induce current






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






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






24. 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






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






26. The formula for the current related to voltage law






27. The 3 types of transformer power loss






28. Used to increase the magnetic flux in a transformer






29. 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.






30. The current related to turns ratio law






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






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






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






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






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






36. Divergence of the magnetic field causes this






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






38. Function of the dielectric oil






39. An instrument used to measure electrical current.






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






41. Transformer losses are classified as _____ and _____.






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






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






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






45. 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






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






47. Kind of wire is the secondary coil in a transformer






48. Copper loss is known as _____ loss.






49. 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






50. Modern; extremely efficient-more effective coupling between primary and secondary coils; smaller and lighter