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Transformer Short Circuit Current?

Discussion in 'General Electronics Discussion' started by Cburg, Nov 24, 2012.

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  1. Cburg

    Cburg

    2
    0
    Nov 24, 2012
    Hi Forum,
    I am designing a capactive discharge circuit that pulses current into an inductor. To charge the caps, the input transformer sees near "short circuit current". I have found that with a small transformer the current is limited about right just by the high impedance of the transformer. I now need to find a bigger transformer, but cannot find the impedance or short circuit current specs on the transformers. Are there any guidlines for knowing about what these parameters might be; like 10X the rated current, or something?
    Thanks!
    Mike
    :)
     
  2. john monks

    john monks

    693
    1
    Mar 9, 2012
    I am not clear what the application is. I am not aware of transformer specifications for maximum input current in a capacitive discharge system. But your question implies to me that you intend to run your transformer to such a high rate that your concerned with overheating.
    Is this the case? Normally with a capacitive discharge system you are more concerned with exceeding the secondary maximum voltage rating, not the primary. It is very difficult to damage a primary winding with a capacitive discharge system. The only transformers that I know that might have maximum input current ratings in this application are automobile coils. Normally when testing a transformer in such application I deliberately exceed the voltage ratings just to see what I can get away with. And usually the secondary arcs internally. And sometimes, but rarely, this damages the transformer. Is this for a switching power supply or automobile ignition system? Are you thinking in terms of saturating the core?
     
  3. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    What is the frequency of your dc inverter? You don't need big transformer for cdi using high frequency dc inverter..
     
    Last edited: Nov 24, 2012
  4. Cburg

    Cburg

    2
    0
    Nov 24, 2012
    Hi Guys,
    The application is a magnetic pulser to generate a magnetic field. Frequency is .5 Hz to 10 Hz with two different capacitor ranges. The caps draw near short circuit current on charging with the transformer I have now, and limits the current well, but at the higher frequency, it overheats. I measured current and it is 6x rating, so have ordered a larger one accordingly (plus a little). I think I will need to use a current limiting resistor also, now, but don't know what to expect.
    Thank you!
    Mike
     
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