Let's take a look at our Phillips Lighting Extreme Surge Protector as used in the street lighting and other applications and this is basically wired in parallel with your supply. It's got a couple of holes for mounting it into a gear tree or you can actually screw it onto just a hole in the metalwork and it's got uh, push fit connectors and if you look very carefully and it's not very bright, see, there'll be green flickering dot. That is the indicator that everything is good. Looks like an LED but it's very, very dim, right? Tell you what.

Let's unplug it. get the wires out. Hopefully it doesn't hold a huge charge. So I shall push down in these connections because they are just pushing connectors and we'll open it up and I shall take it apart, which is more or less the same as opening it up.

Let's Zoom down onto this so we can see it together. Hopefully this is going to come apart easily. That's not bad. Is it going to be potted? No, it's well, it's kind of parted.

If these are what I think they are. Does this come off? It does. There's the LED There's a gas discharge tube going to the Earth Here are these look like a I Wonder if these are from TDK as well. These are very similar to the ones I Kind of want to take one of them off? Uh right.

I Probably will. Okay, let's take a picture of this and then a reverse engineer and we can see what's inside one moment please. Bit of desoldering and reverse engineering done and resume. I Thought these were potted and they're not.

so that means we can do a little experiment with one. We can trip the thermal effusiness. So what I'm going to do is I'm going to put a little bit of soda fresh soda onto the Soldier arm so it couples on well. I'm going to bring it up here I'm going to zoom down and then I'm going to focus on that so it's nice and sharp and then we'll Heat this up because this is a spring attached to a metal oxide varista on the other side and when it gets hot, it just pops open like that.

How simple is that? That is really quite neat. Uh. also technically speaking, you can put a new metal ox or verster and reset it, but that's not recommended. It also means that technically speaking, can reset this one.

However, that's also quite nice because look at the heat path here of the spring, which means that when you soldier in, it's less likely to stress the device. Very nice. and the metal oxide Barista itself is just going in a bit of a hair. well.

I can pull this out now. more or less can I pull this out. Let's get that connection there which is going down a little metal pin. Oh that metal pin is going down.

this sort of stop not coming out. Uh, but this other one is going down a bit of sleeving. or is that a bit of sleep. No, it's all molded in uh tubes in this, right? Say what? Let's Get down under there schematic one moment please.

So looking at the circuit board, it's quite odd because I wonder if the circuit board is designed to have multiple functions because there's positions for capacitors. it streams that they've shown them as round here and here and here and here. Plus all these links marked F, one, two, and three. there is this uh, gas discharge troop it's Epicos, which is part the TDK thing again.

I think these are also TDK components which TDK as soon as I see TDK I think of old magnetic uh cassette tips, but they're clearly they're a big player in the search suppression because meanwhile, and Philip said, that's two of the biggest players using their components. The other thing you can find on here is a resistor which is part of the circuitry limiting the current to this Led, but it's not the main component limit in the current to the LED 220k Red Red yellow. Actually, let me just let me check something. Nope, that's fine.

It's 220k Red Red yellow which is a two, two, and four which is four zeros. so that's 220 000 Ohms. But then they've got the gold and then they got a black one that's uh, that's going to be one of those weird resistors with, uh, maybe just an indication that it's also a fuse. So I'm not really sure about that.

That's quite strange. but then it's going to the LED but via other circuitry, let's take a look at the other side and this is where it gets more interesting. We have the uh, incoming Supply on these push down connectors. Loads of support here.

We've got these mysterious pads that look as though they could actually have be a more basic filter just with basically a capacitor between live neutral and the Earth. And maybe there's a version that does that, but they're going to these uh, metal oxide wristers with the built-in fuses I have shown earlier and the middle pin is this sort of feed pin to that fuse and then it cuts over to the actual metal oxide that Varissa is the charger pins. and uh, you've got one across live neutral and you've got Uh two going from life to Earth and neutral to Earth. But then they don't go straight to Earth There is that gas discharge tuberated about 600 volts I Think, uh, going to the Earth to provide separation so there's not current flowing to Earth.

The circuitry for the LED is a tiny little capacitive dropper, and by tiny I mean that capacitor is an extraordinarily low value. like three nanofard and then a very simple uh, the the simplest possible way to make the LED light. I'll show you it in the schematic. So here is what we have.

Uh, right, I'm just going to pause them and just double check something. Something is casting doubt into my mind at the moment. Nope, It turns out there was no reason to be doubtful at all as often it happens. So these devices are T20 K320, 324 RMS rated and they're designed that at the point normally you determine the voltage I'll Zoom down a little bit of these uh, metal oxide roosters is the point at which they're passing one milliamp that's just a threshold.

volts are starting to turn on. In this case, it's apparently 510 volt. Um, it's interesting to note that components inside the actual disk itself is called T20 Key 320. And so we have the neutral command via this thermal Fusion that the way it goes through the thermal fuse, the neutral goes through this thermal fuse and then it goes through this thermal fuse and then it goes to the monitoring circuitry.

or the live goes through this thermal fuse and goes to monitoring circuitry. So any of those fuse is breaking will actually trigger the LED to go out. so the metal oxidation across live in neutral is just connected after that fuse. If it starts overheating the neutral brake and that will break the circuit through that, the ones to Earth go from the neutral view of that fuse and that fuse to the Earth Uh via this gas discharge tube.

The Live likewise goes through that fuse to the gas and the metal oxide to the gas discharge tube. The circuitry here is basically a capacitive dropper, but the most absolutely minimalist type. It has a tiny capacitor that's why it's just barely a glow, but it's probably a gallon of no trade LED so make ramps are fine. It has that 220 key resistor, the three nanofard capacitor.

Um, it's got the LED then a reverse diode across that because otherwise the capacitor can't discharge and charge and that's how it works. basically the capacitive dropper and then it's got a 27 key resistor. cross it just to shunt any leakage which I wouldn't expect I'm not sure if that's even needed, but they've put it in for a reason. Um, so there we have It Ultimately, it's basically just a metal Ox rooster cross lava neutral live in Earth neutral and Earth with an extra battery or the gas discharge tube.

And if any of the thermal fuses go, the LED goes out. Not that any of your average Street lighting Engineers Because this is where these are really intended for use in street lights and other applications like that. Not that they're ever going to ever look at the Led to see if it's lit or not. they just wouldn't do that.

Uh, because that's nature. But if I was being cynical, I'd say that this is primarily a device designed to get these units out of their warranty. And it's worth mentioning that on the Isle of Man they recently refitted a lot of the lady in Douglas the means of capital city of Hellman with a state-of-the-art architectural LED lighting fixtures with RGB color changing and they get struck the lightning and it took the absolute whole lot out. So um, maybe they would have benefited from these uh devices that would have actually perhaps prevented that if it was the power supplies that blew up or but not if it was the actual like the control Network that blew up instead.

But interesting stuff. it's quite well made. It's designed for use in street lights, so I'd expect to be quite rugged. An interesting little surge suppressor.

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