Overvoltage protection for Seasonic S12 600 watt power supply ?

A local power company dropped an 11 kV line onto the local 110 volt line. Bad, bad, bad, bad, bad, bad!

Regarding over voltage.

Mostly the words "over voltage protection" do actually mean "transient protection". This means a short duration high volttage pulse (in the kV range during microsec.) can be absorbed by the power supply without damage. Also lower voltage peaks with somewhat longer duration (ms) can be absorbed by the transient protection.

Many times Varistors (VDR) are used at the Mains input in combination with filters. Varistors can handle large currents for a short time but will run hot or even may rupture in case of moderate overload for prolonged time (due to over dissipation).

According to the media (I live in the Netherlands), the over voltage took about 20 minutes and was 300 V. We may assume that 300Vrms is mend. This voltage is not that high that a primary fuse will blow immediately, so this is a main reason for lots of damage (and damage that still has to occur because of stressed components).

Regarding your power supply, I checked the "data sheet" but the data sheet doesn't give much information. Whether this supply can handle this overload depends on many things.

I believe the best thing you can do is try to find out what happened exactly (overload voltage and duration) and contact the manufacturer. It is possible that the power supply did survive the overload, but will fail within months.

Regarding protection. Electronic equipment has to have some form of transient over voltage protection to fulfill basic requirements (CE for European Union). It is free to the manufacturer to do actual testing. Often products can be found that has no protection (or the components are not on the PCB while the footprints are).

There are few requirements for prolonged mains over voltage. Most equipment is designed to handle mains voltage + 10%. When higher mains voltage is applied (as recently in the Netherlands), the only requirement is that no dangerous situation occurs (like fire, electric shock, etc). This means equipment may fail.

Power supplies may have protection for the low voltage outputs (in case of the power supply fails). The last resort protection is mostly a so-called "crowbar". This circuit is connected in parallel to the output to be protected. It generated a short circuit when the output voltage (for example 5V) exceeds a certain threshold. The short circuit (mostly done by a "thyristor") does blow a fuse or other device preventing further damage to the low voltage circuitry (like the motherboard).

I hope this will help you a bit.

Best regards,

Wim

Overvoltage protection means the 3.3, 5, and 12 volt outputs will not get too high as to damage computer components. This concept has been industry standard for generations. A power supply - even when it fails

- must never damage any computer parts.

Overvoltage protection is not transient protection from AC mains. It is clearly defined even in Intel power supply requirements - with numbers:

Meanwhile other industry standard specs demand that an appliance even withstand 600 volts without damage. Computer power supplies are supposed to be more robust. They should even withstand thousands of volts without damage - again as even defined in specifications with another important parameter - time.

Overvoltage protection is a circuit that detects that overvoltage and then lock out the supply. This protection feature requires power be completely removed to be reset.

Notice another feature also required by same specs in all supplies. Short all power supply output wires together and no power supply damage can occur. Of course many computer 'experts' don't have basic electrical knowledge. They buy power supplies on price. Therefore some power supplies can be damaged by that short circuit AND are also missing overvoltage protection.

Overvoltage protecti> A power company in the Netherlands caused a voltage "punch" of 300

I use the same brand supply. I have a gut feeling it will be OK. This is a SMPS that works from 100 up to 240, so it is engineered for a very wide voltage range. While 25% overage is pretty bad, there could be significant guard-banding in this design as it is not a cheap power supply.

I never did an off-line switcher design, but that is what you would want to research.