On 10/08/2012 11:54 AM, David VanHorn wrote:
> Can anyone help me?
>
> I'm looking for a source of desktop universal input SMPSs that will do
> at least 2.7A at 24V.
> Those are easy to find, but the next bit isn't.
>
> In case of overcurrent, I need the supply to shut down until the plug is =
pulled.
> Everything I have found has "Hiccup mode" or "Auto-Restart" which is
> unacceptable.
> A supply that operates in this mode could cause a disastrous fire.
>
> There are connector and ratings requirements also, but I will discuss
> that with the vendor.
> Surplus onesies would be interesting in that they would point me to
> the proper vendor to get them from in bulk.
>
> VERY interesting reading:
> http://www.kodiakconsulting.com/page19/assets/Low%20Voltage_The%20Incompe=
tent%20Ignition%20Source_Final.pdf
>
> Thanks!
Why not add a SCR that fires when it reaches a certain current=20
limit...It would "lock"/crowbar the output until the power supply has=20
been unplugged and the SCR's gate releases. Reading the voltage=20
developed across a low value (.5ohm) high wattage  (5~10W) resistor in=20
series with the 24v leg and firing the gate of the SCR when it reaches=20
your current limit... A few components and a standard (available) 24v=20
SMPS power supply. You would need to handle the turn on surge also.
Dave
--=20
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