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Transformer design.

  1. Feb 9, 2007 #1


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    I may have a project in which I need approximately a 10 KVA transfomer. I've done a bit of research on-line and have some guidelines. Line/load regulation is of less than typical consequence. The turns ratio will probably be about 2:1, probably slightly less. My main questions are core material (I may cut my own out of sheet metal) and how much to oversize the core. I understand that running close to or into the knee on the BH curve gets better regulation although I can't say I understand why. Obviously larger wire gets better regulation since there will be less copper loss. Also, getting a core large enough so that the volts per turn ratio allows fewer turns is an advantage here since fewer turns in a given area allows larger wire. I guess I just need a bit of direction. How will the thing run on mild steel core material? Weight is of little consequence. I don't care if it's as big as a refrigerator. :smile: Well, maybe not quite that big.
    On a similar subject, I need to build a saturable core reactor. Anyone here have experience with this? It needs to pass 50 amps without breaking a sweat. I've done a little research on these devils too, but would welcome any advice. I would think mild steel for a core on one of these would not be a problem as it could be on a regular transformer. It will be used to limit current in a series circuit.
    Everything here will be at 60 hertz.
    One last thing, please no safety lectures. I've been messing with power of this sort for quite a long time.
  2. jcsd
  3. Feb 9, 2007 #2


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    That's a good size transformer :eek:
    Don't know very much about this.
    It does occur to me that you might find a transformer like this in an arc welder, but i suspect the turns ratio is more like 4:1. Perhaps a base core for a rewind though.

    Heat is the big problem.
    Primarily from IR losses in the wire and eddy currents in the core material.
    Ferrite would probably be best core, but getting something that big...

    The reason for BH regulation is that after the knee much of the flux escapes the core and is not seen by the secondary winding.

    A saturatable reactor runs past the knee. The core is intentionally saturated.

    Good luck with that.:smile:
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