Simple Overvoltage protection

[David Gregory]

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

Thanks
David

 

[BobK]

Look up "crowbar circuit"

Bob

 

[Colin Mitchell]

Why would the power supply go over voltage????
What about putting a "stopper" on the control knob ????

 

[David Gregory]

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.

 

[Samodelkin]

Let's bump the thread )))

Hi,

I would like to add overvoltage (not lightening, but N wire disconnection) protection to the apartment board. Currently I have such spike protection (Uc=275V 220V network) installed:

L and N connected to upper side, and PE to bottom.

So I see following options (besides to purchase some relay and replace board for bigger one):

1) Swap PE and N, thus varistor will limit L-N voltage, and will cause overload switch activation, disconnecting power.
2) Add low voltage varistor (10-25V) between N and PE.
3) Add SSR like

with input connected to N-PE, and output with resistor 2-4 kOm between phase and PE, thus causing residual-current device disconnect power.

What do you think?

 

[Harald Kapp]

Let's bump the thread )))

NO, not an old one from 2016. Please create your own thread. This one closed.