What is eddy Current ? - PowerPoint PPT Presentation

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What is eddy Current ?

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This article is about eddy current. What is eddy current? How is eddy current generated? How to limit eddy current? Eddy current applications If you want to read more related topics of electrical engineering please visit our website: – PowerPoint PPT presentation

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Title: What is eddy Current ?


1
EDDY CURRENT
  • Electrical eddy current is the current that
    originates within the current carrying conductor
    by changing magnetic field due to Faraday's law
    of induction.
  • Eddy current circulates in a closed loop within
    the conductor, perpendicular to the magnetic
    field that generates it. It may generate when a
    conductor is exposing to magnetic field or when a
    moving magnetic field gets closer to a stationary
    metallic conductor.

2
  • "Anything that changes the direction and
    intensity of magnetic field induces eddy current
    in conductor
  • The value of current induces is directly
    proportional to loop area, magnetic field
    strength and rate of change of flux while
    inversely proportional to the material
    resistivity.

3
HOW DOES EDDY CURRENT PRODUCE?
  • As we know that in magnetic field, charged
    particles experience a force. There are so many
    free electrons in conductive materials that move
    around within the material. As these electron's
    experiences a force due to change of magnetic
    flux within magnetic field, creates circular
    electric field perpendicular to that magnetic
    field. This electric field produces a flow of
    current in small loop, which is eddy current.

4
WHAT DOES EDDY CURRENT DO?
  • Lenz's law states that, as the induced eddy
    current flows, it will originate its own magnetic
    field. The direction of this magnetic field will
    be such that it opposes the external magnetic
    field. Thus, eddy current reduces the overall
    magnetic field. This property of reducing overall
    magnetic field is useful for stopping rotating
    power tools. Thus, eddy current causes energy
    loss in alternating current operating machinery.

5
LIMITING EDDY CURRENT
  • Metallic conductors are sliced into thin metal
    sheets to reduce eddy current. This reduces the
    surface area of conductor resulting in lowering
    eddy current loss. This phenomenon is adopted in
    transformer manufacturing world widely.
    Transformer cores are cut into thin sheets. These
    sheets are then laminated with insulator in
    between them to limit induced magnetic field.
    Thus result in limiting transformer iron core
    loss and heating loss.

6
APPLICATION OF EDDY CURRENT
  • Eddy current also has advantages up to some
    extinct. It can be useful to diagnose cracks
    within the conductors. Since cracks within
    conductive material prevents formation of loops
    in that region thus resulting in detecting
    defects in materials. This is called
    nondestructive testing (NDT) and is often use to
    test airplane surfaces.

7
  • It can also be useful for braking purposes. As
    mentioned above, it can be helpful in quickly
    turning kinetic energy into other form of energy.
  • Another application of eddy current is its use
    in certain type of proximity sensors to observe
    the vibration and function of rotating shafts
    inside their bearings. Those sensors are
    extremely sensitive to very small displacements
    making them well suitable to examine the minute
    vibrations in turbo-machinery

8
  • It can be useful for the identification of coins.
    The coin rolls beyond a stationary magnet, and
    eddy currents slow its pace. The eddy currents
    strength and thus the retardation, relies upon at
    the conductivity of the coin's metal. Slug coins
    behave differently than genuine coins.

9
  • Eddy current is also responsible for skin effect
    in high voltage conductors.
  • To read more about skin effect follow the below
    given website link.
  • www.electricalride.com
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