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Transformer Hum

Discussion in 'Electronic Repair' started by Javier Perez, Jul 6, 2004.

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  1. Javier Perez

    Javier Perez Guest

    Why does ballast transformer hum? what is actually moving inside it to make
    it hum? I wonder
     
  2. Art

    Art Guest

    Electro-Magnetic Resonance. The magnetic materials [transformer core pieces,
    etc] within the ballast are reacting to the frequencies of the applied
    current source and vibrating. The noise will vary with the load, ambient
    operating temperature, and length of time in operation. The hum you hear is
    the result of these items actually vibrating within the ballast assembly.
     
  3. Asimov

    Asimov Guest

    "Javier Perez" bravely wrote to "All" (06 Jul 04 04:11:48)
    --- on the heady topic of "Transformer Hum"

    JP> From: "Javier Perez" <>

    JP> Why does ballast transformer hum? what is actually moving inside it to
    JP> make it hum? I wonder

    It is an effect called magnetostriction. Every time the magnetic field
    reverses the atoms in the metal vibrate away from each other and then
    closer again. On a long piece of metal as in a transformer this may
    only be a difference of 1 micron but at 120Hz it is easily heard. The
    cure is to mount the transformer on rubber isolators and screw all the
    laminations down tight. There will always be residual hum.

    A*s*i*m*o*v

    .... 'Keep the smoke inside.' -- 1st Rule of Electronics.
     
  4. Now and then

    Now and then Guest

    because it does not know the words
     
  5. Cougercat

    Cougercat Guest

    Ballast hum is usually due to loose iron laminations in the transformer.
     
  6. Jerry G.

    Jerry G. Guest

    I see that in the other replies you received some very factual reasons why
    the transformer can make a buzzing or humming noise. As these ballasts
    transformers age, they will get louder, because the laminations and windings
    will loosen up a bit. This is a more simplified reason for the hum you are
    hearing. They all hum to some extent, but the level of this noise will
    increase of a period of time. The fix is to replace it.

    --

    Jerry G. GLG Technologies GLG
    ==========================


    Electro-Magnetic Resonance. The magnetic materials [transformer core pieces,
    etc] within the ballast are reacting to the frequencies of the applied
    current source and vibrating. The noise will vary with the load, ambient
    operating temperature, and length of time in operation. The hum you hear is
    the result of these items actually vibrating within the ballast assembly.
     
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