Transformer help, please!

Discussion in 'General Electronics Chat' started by GeneratorPanels.com, Dec 6, 2008.

  1. GeneratorPanels.com

    Thread Starter New Member

    Dec 5, 2008
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    I have been searching the whole internet for this transformer and can't find it anywhere! We own an electronics repair company for emergency power equipment, so we really need to find a replacement or alternative. It is labeled CA 2300. It is 1VA, with one primary and one secondary coil. The primary coil is 280V and the secondary coil is 12V. Does anyone have any suggestions on where I can look for this part? We would be very grateful.
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    Where is the power coming for the transformer and what does it power?
     
  3. GeneratorPanels.com

    Thread Starter New Member

    Dec 5, 2008
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    It is for an automatic transfer switch. The 280V primary coil is fed by the main utilities power supply, and the 12V secondary coil is the output to the controls on the circuit board. It is used for sensing a power outage from the main utilities supply. The transformer is mounted on the circuit board.
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    I guess your mains voltage is 240VAC, so you can use a 240/12 step down transformer.
     
  5. GeneratorPanels.com

    Thread Starter New Member

    Dec 5, 2008
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    Yes, that's okay for most applications, but some of the applications are in Guam & Mexico where the utilities voltage is actually 277V. These are the areas of our concern.
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Get in touch with a famous company which makes transformers. Maybe they have them or can produce them for you, if you want many.
     
  7. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
    How about using a 240V to 10Volt transformer.
    It will give 12v out if fed with 280volt.
     
  8. GeneratorPanels.com

    Thread Starter New Member

    Dec 5, 2008
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    0
    You guys are right... keep it simple. Thanks for the reality check. We'll have them custom made.
     
    Last edited: Dec 7, 2008
  9. mik3

    Senior Member

    Feb 4, 2008
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    You can't really use a 240/10 transformer, even if you think it gives you 12V output when its input is 280V. This is because a transformer core is designed to pass a maximum amount of magnetic flux without saturating (magnetic saturation) for a given input voltage. The magnitude of the flux (ideally) equals:

    B=V/(NAω)

    where

    B=magnetic flux magnitude
    V=primary voltage magnitude
    N=primary turns
    A=cross sectional area of the core
    ω=supply frequency

    You see that if you increase the voltage from 240V to 280V, magnetic flux will increase and the core will saturate. This will cause more current to flow through the windings and overheat the transformer.
     
  10. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
    This is perfectly true in theory. However in practice there should be enough safety margin in the transformer design to run a 240V transformer at 280v without running into core saturation problems. After all it only exceeds the rated voltage by 16% and if a transformer can't handle that then it might be time to sack the engineer who designed it.
     
  11. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Alex,

    I know transformers are designed to handle variations in the mains supply voltage but I did not know they can do it up to 280V (for a 240V transformer). It looks like quit a big difference.
     
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