transformer

Discussion in 'General Electronics Chat' started by mines, Dec 17, 2013.

  1. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    Hi I'm currently rewiring a transformer. I ground the top wields off and took it apart. The 120V. winding are fine and I'm stepping it down to 12V. I was surprised to find a second set of laminated iron in-between the 120V and the other two sets of windings. What is this for and should I put it back in between the 120V and the 12V when I install my new windings?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,056
    A picture would help ! Maybe someone already knows what you mean, but I don't.
     
    #12 likes this.
  3. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    I can't figure out how to post a pic. Its asking for a "url" format? and won't accept my picture. Can I put it in an e-mail and then send it to this web site?
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Try explaining it. Someone may get it.

    What would the core look like with no windings?

    E and I?
    O?

    What was original purpose?
    Microwave?
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,554
    2,375
    Maybe you are talking about the magnetic shunt? If so it should be driven out if it is and is possible.
    Max.
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
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    Picture....................................

    Per email................

    "The two things sitting on top that look like candy bars are actually laminated iron rapped in paper. They fit in-between the windings of which only the 120V is installed."
     
    Last edited: Dec 17, 2013
  7. inwo

    Well-Known Member

    Nov 7, 2013
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    Looks like a mwo transformer.

    Remove, like MaxHR says unless you need to limit current.
     
  8. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    So then I take it that reinstalling these little bars in-between the two windings is not going to do me any favors. I am still wondering what the heck they are for. I can't see how they would act as current limiters but then it's obvious that I'm still learning about the behavior of transformers.
     
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
    1,531
    Maybe this will help you -
    http://www.magnet.fsu.edu/education/tutorials/java/magneticshunt/
     
  10. inwo

    Well-Known Member

    Nov 7, 2013
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    MaxHR will explain.
    Magnetism theory is my weakness.:confused:

    http://info.ee.surrey.ac.uk/Workshop/advice/coils/leak/weld/index.html

    From that site.

    "The flux generated by the primary winding need no longer travel through the secondary in order to form a closed loop. It instead has the option of following the shorter path through the bar; and this is what most of it will decide to do"

    If only I could understand.:(
     
  11. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    The MOT has current limiting.
    The Magnetic shunts will limit the secondary current.

    So If u need to use lower secondary voltage like me, just don't use the magnetic shunts.

    Googling will help you. Try googling MOT rewinding
     
  12. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    Thank you Headroom and Short buss. Now I understand. I really appreciate you guys.
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Another example where it is used is in SMAW (stick) welding, the O.C. voltage of the transformer could be around 100vac, so when the arc is struck, (short circuit) the current would exceed the rating of the transformer and you would not be able to regulate the welding current.
    By introducing a magnetic shunt the voltage collapses to a suitable selected degree depending on the thickness being welded by adjusting the shunt.
    This shows a bit about shunts and other methods used, particularly fig 2 & 5.
    Max.
     
  14. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    That's very cool! As one of my next projects is going to be a wielder that's a wonderful thing to learn and apply.
    Thanks again ,, Mr. Headroom
     
  15. mines

    Thread Starter New Member

    Feb 9, 2011
    16
    1
    Hay Mr. Headroom Figures 2 and 5 in what? I could find no attachments or references.
     
  16. MaxHeadRoom

    Expert

    Jul 18, 2013
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  17. mines

    Thread Starter New Member

    Feb 9, 2011
    16
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    Max ole buddy ole pal.
    Again thank you very much! That web page is really nice/basic/and very helpful.
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
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    The link in #10 was specific to welders.;)
     
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