Does have Exxos PSU some dangerous design aspects?

[mikro]

Without trying to hurt anyone's feelings or question anyone's abilities, I'm genuinely interested. Pavel makes a serious claim about the danger the PSU could pose, so I'm wondering, is it really like he describes? Is the fuse present on the DC side instead of AC side? If so, why?

Also, if I understand this claim:

The entire bottom of the PCB is poured with copper connected to DC ground. And it is poured also right below the head of metric screw holding this massive toroid transformer. The screw is "dry mounted", without any washer (mechanical engineers head scratching). The ground copper is covered with solder mask, but installing this screw dry way inevitably scratches the solder mask off, making the entire toroid mount metal bracket ground connected. Then, when AC winding isolation film eventually fails due to aging and heat, this PSU will turn in a rather heavy electrocuting device and spark generator, taking an ST into the hell with it.

correctly, the solution is simply to have a washer mounted there? (I think I do, just making sure)

[exxos]

There is a high temp washer under the PSU isolating it from the gnd fill. The washer is made from the same materials that are used to isolate high voltage cables with. Same with the top part of the metal bracket. If the transformer literally melts down it would blow the mains fuse.

Plus most of Centurion claims are pure works of fiction. I mean centurion tech even complained about the sticker on the PSU. His post was nothing but defamation along with the usual a$$hole comments on A$$hole-forum. I really should be suing all those people for what they have done.

I also read on other forums that his PSU is simply DOA or shuts down after a hour of powering a stock machine. I've had several people report the same to myself ever since he started selling them. I didn't take to public forums and slate his products like he unjustly did to mine! I also heard and read he gives similar abuse to his own customers. Most of what he sells is spun off the back of someone else's work. So that's all you need to know about centurion tech really. Then people wonder why I ban people I want to design hardware not deal with abuse from trolls. Its why I setup this forum to get away from it all as I got little support elsewhere with dealing with such people.

I am not responding to any comments as I have tried to educate people for the past 20 years and just don't bother anymore. It would literally take me all day to pick apart all his claims, I would rather save the guy the embarrassment. He said it in his own words he has a new PSU coming, so of course hes going to try and kill the competition. He must be really desperate to go to such lengths. If you or anyone believe any of his BS, then go join the other armchair experts on other forums and leave us experts to get on with real work.

[exxos]

This was the only image I could find of a side view of the washer.

110v-min.png (353.61 KiB) Viewed 4135 times

The current batch of PSUs I had custom washers made to my specification. So you see centurion is making this all up along with his other claims.

[mikro]

Plus most of Centurion claims are pure works of fiction.

I can't judge either side's claims as I lack education in this matter but the point is elsewhere. If I come to a forum and say "Exxos PSU sucks and it is lethally dangerous because as we all know green colour is more conductive than blue and it can kill you", you may think "what an idiot" but if other 100 people read that claim and it stays unchallenged, some percentage will believe it and spread the word of your PSUs being dangerous further.

That is why I think that AC/DC fuse claim (and perhaps others) about PSU safety should be clearly explained, no matter whether it is a competitor, troll or regular user asking.

[exxos]

That is why I think that AC/DC fuse claim (and perhaps others) about PSU safety should be clearly explained, no matter whether it is a competitor, troll or regular user asking.

Well my aim is to protect the machine at all costs. Do you want the smoothing capacitor dumping 50+ peak amps into the machine on a total failure ? I sure hope not. That is what he is advocating. That is what happens when you have fuses "AC side" only. So I put the fuse in the DC line so that energy is dumped into the fuse which helps it blow faster. Most of the caps energy is then isolated from the machine. Is it "ideal" no, choices need to be made. I vote with protect the attached equipment. He obviously does not.

Forgot to say, at least in the UK, plugs have fuses in them. I can't speak about worldwide regulations. Though there is a AC fuse in the plug anyway. Having 2 AC fuses may be safer but I'd rather have one AC and DC side. But the fuse is the last resort anyway. Even so, a inline fuse can easily be added if people are that concerned. Though if countries dont have fused plugs, then I think your living in a death trap anyway.

Forgot to say 2: The transformer has 2 inbuilt thermal fuses. So if the core temperature gets to hot, they will blow. So no risk of fire.

[xyzzy76]

The fuse in the plug is only there to protect the mains cable, not the device under power.

[sporniket]

Though if countries dont have fused plugs, then I think your living in a death trap anyway.

In my typical french home, each rooms is protected by a circuit breaker rated at 16A. Some plugs are intended for power hungry appliances like the laundry and cooking, and are rated to 20A and 32A (with proper fatter wires).

Even so, a inline fuse can easily be added if people are that concerned.

Well, I would be one of those that would feel better with such a supplemental fuse. That said, as long as the big wires and switch and the toroidal transformer can withstand the 16A spike that will trip my home safety systems in case of short circuit on the AC side, maybe it's just me being scared by the fact that we are talking about the main power.

edit : feel free to correct me if I am wrong, I am not a qualified electrician.

[GadgetUK164]

Out of interest, which washer are we talking about? I've got one of these to fit here (any day now).

[troed]

Sweden don't have fuses in the plugs - but in the central fuse box. Normally those are 10A for power outlets. The only real reason for having a fuse on the AC side would be that if it trips it won't take the rest of all the outlets with it. You're not "more" protected by a fuse that trips at 1A vs 10A if you happen to be the source to ground ...

/Troed

[Daedalus]

Fuses in plugs in the UK is because the ring mains setup that's common in the UK is typically rated for 32A, and providing 32A cables for all appliances would be ridiculous, so a point is needed where the maximum load is reduced. In the rest of Europe, it's more common to have lower current capacities, so they only have to be rated for 10A, 16A or whatever. Once they are so rated, having a fuse in the plug is redundant. Incidentally, Ireland uses a sort of hybrid system - ring mains aren't that common and we tend to favour the mainland European topology at 16 or 20A, but still use the UK plug and socket system and align most regulations. Best of both worlds

In general, the whole idea in any protection system is that everything downstream from a fuse or breaker should be able to safely handle anything up to that current. If it can't, it should be designed to fail safely. You don't have any additional fuse in a lamp, for example, because the bulb fitting, switch and cable will all be rated for at least the same current as the specified plug fuse, which could be 1A or 3A.

It's common for PSUs to have a fuse on the AC side for this reason, because the PCB traces and various components might not fail safely in high current conditions, and they're usually for a far lower current than the mains plug, switch and cable can handle. They're often not intended to be replaced, being soldered in place or even embedded in a transformer's windings, the thinking being that if you end up in a situation where you've got that much current flowing, there's something drastically wrong and the PSU should be dumped.

That said, I'm all for a fuse on the DC side too, with the caveat that is should be easily replaced as a DC short is far more likely to happen in situations where people are messing about inside their machines. When I build ATX adaptors for retro machines, I include fuses to protect the machine from the 40A+ that an ATX PSU might pump through a short without shutting down. And it certainly sound like this guy is trying to drum up business for his own units. Not without precedent either, look at how IComp spend a year or so blaming every fault with their products on the PSU while they developed their own supply...