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. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.






2. 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.






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






4. What does transformer efficiency mean?






5. An instrument used to measure electrical current.






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






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






8. Copper loss is known as _____ loss.






9. 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






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






11. 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.






12. The terminals of the low voltage winding are marked _____.






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






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






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






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






17. The formula for the voltage related to turns ratio






18. A simple design has a core within each coil






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






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






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






22. 3 types of transformers






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






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






25. 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






26. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.






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






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






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






30. The 3 principle components of a transformer






31. 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.






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






33. To minimize ________ in transformer construction - the primary and secondary windings are placed on the same leg(s) of the core.






34. 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






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






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






37. This type of transformer power loss is caused by the continually changing AC current movement which constantly magnetizes/demagnetizes/re-magnetizes






38. A transformer loses less than _% in energy






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






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






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






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






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






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






45. Transformers with 4800 volt primaries and 120/240 volt secondaries - either pole or subway type - with two secondary windings terminating at internal links which provide for parallel operation of the secondary windings at 120 volts or series operatio






46. A ___________ transformer is a continuously adjustable Autotransformer.






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






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






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






50. If the transformer is used as a _____ transformer - the low voltage winding is the primary.