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Simple Overvoltage protection

Discussion in 'General Electronics Discussion' started by David Gregory, Nov 5, 2016.

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  1. David Gregory

    David Gregory

    Nov 5, 2016
    I have a 13.8v, 30 amp power supply that is over current protected, but not over voltage protected.

    Am I correct in thinking that a simple zener diode across the outputs, and an in-line fuse is all I'll need to have a crude, but effective over-volatge protection circuit?

    If I use a zener of 14.4v or there abouts, if voltage exceeds this level, the zener will breakdown and short out the PSU's output, and blow the fuse.

    My question is, for a 30 amp supply, what zener will I need to survive the time it takes to blow the fuse, considering it will be drawing 30 amps approx.

    I hope I'm making sense :)

  2. BobK


    Jan 5, 2010
    Look up "crowbar circuit"

    duke37 likes this.
  3. Colin Mitchell

    Colin Mitchell

    Aug 31, 2014
    Why would the power supply go over voltage????
    What about putting a "stopper" on the control knob ????
  4. David Gregory

    David Gregory

    Nov 5, 2016
    Failed Voltage regulator? Failed, or dirty potentiometer? (it has variable output). I'm assuming it must be plausible to go over voltage, or why else would a great many PSU's have over voltage protection?

    Thanks BobK.... A crowbar circuit looks simple enough. I was just looking for something as simple as possible to keep from overly modifying the PSU.
    BobK likes this.
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