Transformer theory Part3

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Author:
johnbowens
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62653
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Transformer theory Part3
Updated:
2011-12-29 14:20:17
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transformer theory
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tranformer theory NJATC ISBN: 978-0-08269-1604-4
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  1. What causes and prevents telescoping in a transformer? Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP25
    • Cause: two electromagnets and a short circuit condition
    • prevents: The primary and secondary windings are electrically centered with respect to each other on the core leg.
  2. What can increase the probability of telescoping as it pertains to the customer? Transformers Principles and Applications 2006 , (notecard set xfmrs 3) PP25
    When the customer connects to a tap point other than the standard ratio, the electrical center of one of the windings is shifted from the center of the companion winding.
  3. What transformer design offers the best possible coupling between the primary and the secondary? Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP27

    These transformers are used most commonly in what type of applications? Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP 27
    toroidal

    In relatively high-frequency applications, such as audio and RF Components
  4. The four types of bushings used on transformers as main lead entrances include? Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP 31
    • 1 solid porcelain
    • 2 cable or pothead terminators
    • 3 oil filled (high voltage) pictured above
    • 4 condenser bushing (high) voltage) from underground to overhead
  5. Shell type transformers are called this why? Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP 27
    Because the metal body surrounds the core. The extra metal helps keep core leakage to a minimum, but increases capacitance between the primary and secondary.
  6. The use of askarel as a liquid coolant in transformers was banned in the U.S. in _______, is nonflammable, and decompose to form ______ and toxic chemicals like_______. Transformers Principles and Applications 2006, (notecard set xfmrs 3) PP 27
    • 1977
    • hydrochloric acid
    • dioxins
  7. For every 10 degrees Celsius rise in temperature above the transformers rated limit, the life of the transformer will be reduced by _____ percent. Transformers Principles and Applications 2006 tech fact, (notecard set xfmrs 3) PP 24
    50
  8. The property of ferromagnetic materials where the magnetic induction of a coil lags the magnetic field that is charging the coil is called what? Transformers Principles and Applications 2006 (notecard set xfmrs 3) WB 7
    hysteresis.

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