Surge Protection 3 - Types and Teardown of Combined 1+2+3

Overview of the three types of surge protection, and what's inside a combined Type 1+2+3 metal cased Furse surge protection unit.
Teardown starts at 13:48
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[@seanpassant3174]

The types of SPD are determined by the testing protocol laid out in IEC 61643. Type 1 devices are "Lightning Arrest Devices" and are tested against the 10/350 wave shape, type 2 devices are for transients, inductive loads and switching surges these are tested against the 8/20 wave shape both type 1 & type 2 should be installed in parallel in UK so under normal circumstance they see no load. Type 3 are designed for very close proximity protection of terminal equipment they are tested against two wave shapes 8/20 (a lower level than the type 2) and the 1.5/50 wave shape. Type 3 devices are normally installed in series and as a result have a much lower current rating. Always ensure that the SPD's you buy are certified to meet IEC 61643 and that they are coordinated with one another, the best way to achieve this is to buy from a single family of devices and ensure that it is certified as coordinated.

[@muzikman2008]

I used to fit those furse spds in CCTV systems years ago. Just movs and gas discharge tubes. The failure of that £800 unit is prob due to the 5 burnt out resistors on the monitoring board. Should have replaced and tested it, bet it would work. Great teardown JW enjoyed that 😎👍

[@nophead]

Looks like the varistors are designed to desolder themselves when they fail and get hot. The springs then push them up through the membrane to sever the traces. As others have stated it looks like they were all still good and the control board had failed.

[@Gismho]

Mr Ward. Your videos covering surge protection are excellent, well explained and concise. Thank you!! As an aside, I live in South Africa where my main concern is protecting household appliances (including TVs, PCs, etc.) against transients induced by our national electicity supplier, Eskom, switching the supply on and off several times a week, almost every week for the past ten years (due to poorly maintained generation plant and corruption) to conserve capacity and prevent a national grid failure due to potential overload (through increased demand and thousands of illegal connections). The repeated on/off supply interruptions have damaged many distributor substations (several catch fire, some explode!!) throughout the country and many households experience damage to their electrical/electronic equipment when power is restored, occasionally accompanied by initial voltage surges. Hence my interest in your "tutorial".

[@milos_radovanovic]

Could it be that failed MOV will heat up, self un-solder and be pushed through plastic sensor by the plastic cards and springs?

[@ThePa1ch]

You are correct.

[@UberAlphaSirus]

I was thinking this was a bit of a convoluted way to do it. But then I thought, on a big surge it would probably blow up if it didn't.

[@milos_radovanovic]

I don't think it warms up during surges, but after the failure due to exposure to regular line voltage.

[@echothehusky]

I'm surprised that top card didn't slide out of the vertical fuse PCB, those certainly look like pin sockets.

[@jwflame]

Further investigation reveals that it does.

[@echothehusky]

@@jwflame That would certainly make manufacturing easier!

[@ThePa1ch]

This SPD was clearly still alive (the metal oxide varistors haven't desoldered) and the monitoring circuit had packed up. Not really good enough for a £800 device. Could carry on using it if you fix that fuse +/- the resistors if you still need monitoring.

[@UberAlphaSirus]

R 10,11,12 look to be fusable resistors, only because of that terracotta colour.

[@stephenbell9257]

There must be some other fault since the smaller burnt resistors have been grossly overloaded - in normal operation there should be no way that they could generate enough heat to burn the PCB like they have. The other area of the PCB with burning is probably not due to a fault since the resistor type ( looks like a Vishay PR02) are rated at 2W and run really hot so it is not unexpected that some PCB scorching will occur over time.

[@jovetj]

Despite all the money for R&D on products like these, it could still very well be that the resistors are just undersized and ran hot for most of the life of the device.

[@pau1phi11ips]

Hi John, watched quite a few of your videos. Really interesting. I was surprised to see this. I worked for Furse in the R&D department 9 years ago. That 415M1 is quite an old design. They weren't made like that when I left because it was so labour intensive. That fault with those power resistors on the indicator board over-heating was quite common at one point tbh.

[@mikeZL3XD7029]

JW, I noticed you cut your finger, during the video. Thanks for taking one for the team, this was a brilliant look at what is inside these devices. Oddly enough, Furse was bought out by ABB a while back, their stuff is now made in China, wether or not that is a bad thing remains to be seen.....

[@Jone36]

Hiya John, great vid again. Can you do a video on the potential types of tripping/nuisance tripping particularly after a fuse board change. Where an rcd may or may not have been previously installed and has now been introduced and the best way to go about fault finding these. Thanks again!

[@tomschmidt381]

Always nice seeing how different countries address electrical issues. Much to my surprise we treat the 3 surge levels the same way on this side of the pond. The graphic you showed of a lightning protected residence was interesting. I have never seen that and was surprised how much energy makes it into building wiring, even in a protected location. I assume it is a result of the strong EM field during the strike. The MOV you showed in the plug was pretty small and no protection to Earth, doubt it would offer much in the way of protection.

[@stefantrethan]

I thought if you don't have the minimum required length of wire between the different types you need to fit inductor modules between them? So it surprises me to see this combined 1+2+3 type.

[@davidcoghill8612]

The gas discharge tubes are usually wired in series with the MOVs to set a minimum voltage before any current will flow, important as all MOVs are slightly leaky and if you leave them fully in-circuit all the time that's both wasting electricity and shortening the lifespan. You also have to account for the fact that if you've got L-E MOVs, the leakage current to earth during normal operation can trip RCDs, especially as the MOVs degrades over time and the leakage current increases. In a device like this I would guess they've got the gas discharge tubes in line with the type 1 MOVs to conduct in case of large transients, and none on the type 3s to let them deal with small transients. (They'd be arranged in banks of different values so as the voltage of the transient increases more and more MOVs are passing current at each threshold). In the type of SPDs you get in household extension leads (at leas the good quality ones), they're usually wired up with a MOV crossing L-N, then a second and third MOV connected L-E and N-E with a single gas discharge tube isolating the path to earth.

[@Mike_5]

Great video and you can just imagine how much the rip off merchants will bill people for replacing these

[@ferdiandimatgaper2017]

Thank for the video Sir.. it's very nice and important info for electrician beginner like me...

[@michaelagnew7825]

Its likely a lightning strike will enter home via earth cable, but earth terminals are generally considered an output. Are these devices designed to absorb a lightning surge via E terminal ?

[@WiSeNhEiMeR-1369]

HOWdy J-W, Part # 3 = thanks COOP ...

[@antonyharding5360]

Hi jw, fair play my mate, you know your game. Love your vids. Regards Antony Warrington..

[@davegeorge7094]

I like old school spark tubes, they can rock solid, ever see/hear outlet arc with flash lightning strike?

[@martin54123]

Need to fit one of these but I have a question. I live in Portugal in a rural area where my supply is an overhead cable to the front entrance where the supply meter is, the cable then runs underground for 45 metres to my consumer unit, it is single phase TT system. I don't have access to the meter area just the customer side of the counsumer unit, There is a sealed DNO side to the CU that limits my supply to 6.9kVA, this is because the larger the supply the more standing charge you pay and they ensure people don't overload their cables. Should I use a type 1 or a type 2 SPD or both?

[@michaelcostello6991]

If a 100 KA from lightening strike enters the electrical installation how much does the voltage rise on all earthed appliances etc. Would you get a shock if touching something earthed ??

[@tomgeorge3726]

Hi John, at <a href="#" class="seekto" data-time="180">3:00</a> the plug has only one MOV so only providing surge A to N.

[@robertgaines-tulsa]

I thought the skin just hanging there on the tip of his left index finger was rather gross. Of course, I was eating at the time. It looks fairly deep. A bandage would have been nice for those close up shots of his hands. I mean, you could see under it at just the right angle. It wouldn't hurt to use a bandage to protect that from dirt.

[@benbaselet2026]

Wounds usually heal better when they are in open air as long as they are kept reasonably clean.

[@jovetj]

Grow up.

[@robertgaines-tulsa]

@@jovetj Don't be an asshole now.

[@robertgaines-tulsa]

@@benbaselet2026 My point leaving the flap of skin hanging there could cause editional skin to be torn off. Also, that flap of skin might have bonded back onto the wound if it was bandaged after the accident. That's what happens to me. It speeds up healing. Yes, after the wound has has a bit to recover, they do heal faster when exposed to the air. Personally, I would keep a bandage on to keep the would clean while I am working. At any rate, I think it would do more harm than good for him to leave that dead flap of skin attached especially while working.

[@DrGreenGiant]

Since the MOV is in parallel with the device, how does a type 3 protect the device plugged into it rather than anything connected across line and neutral? Doesn't a type 3 protect the whole ring, for example, albeit badly?

[@jwflame]

It will provide some protection to other things connected, but items further away from the device will have less protection. For smaller installations, a combined 1+2+3 or 2+3 can be installed in the consumer unit for the whole installation.

[@oliverwijesooriya2067]

Excellent explanation

[@Tangobaldy]

Are too varistors expensive to add into sensitive electronic equipment? Or is it because like you said in previous video they can fail over time that we don't see these installed as the norm in consumer electronics? Seems odd to add an extension lead with surge protection unless there is good reason not to have it inside a product power supply or in the case of items powered with kettle leads and the like not to be added behind the device power input. If you have a transformer inside a product does it's voltage output increase linearly with voltage being raised?

[@jwflame]

No, the individual components are cheap,. However if manufacturing 10 million televisions, even a few pence on each one can cost millions extra and put a huge dent in the profits.

[@Xclub40X]

I was looking for a video on how to deal with the surge in cases of the coronavirus . . . Maybe this form of surge protection is the answer

[@barnsley1066]

We use these and have them connected to a SCADA system for remote monitoring.

[@timballam3675]

Is supply strung between buildings classed as overhead?

[@jwflame]

Yes.

[@timballam3675]

@@jwflame supply runs up the wall of a house diown the road then along the underside of the soffit boards and between each semi, didn't think about it being overhead supply.. thanks.

[@movax20h]

THe resistors are discollored, because they are the part of the capacitive dropper circuit with the capacitor and zener diode, to form low voltage for the transistors, LEDs and the relay. They use capacitive dropper because the current they need is relatively small, and that way they can save on the transformer. The sensing circuit looks very simple and simply detect if the there is input voltage on all phases, and if there is any break in the sensing strip thingy. The discoloration isn't bad, and pretty common, but obviously better designed circuit would have better resistors with higher power rating and spaced further from the PCB.

[@ubodlaj]

I could use this for household as well rite?

[@Richardincancale]

Very interesting - thanks. Are the SPDs required for TT systems more expensive? I’d presume they need even more MOVs etc. To cope with the higher resistance Earth?

[@jwflame]

Not usually, the differences internally are minor. Some can be used on both TT and TN systems.

[@ChumpusRex]

They use similar MOVs (but they may have a more powerful GDT/spark gap for differential protection). In an SPD for TN-C-S, the internal protection is configured - L-E and N-E. The low earth resistance, means that fault currents through any MOV are not limited, and that over-current protection will operate correctly to disconnect the SPD in the event of failure. In TT, the continuing fault current to earth cannot be relied on to trigger over-current protection. In this situation, an SPD with internal connections L-N and N-E is advised. In this case, the continuing fault current through a L-N connected MOV will not be limited by local earth resistance and over-current protection should operate correctly. One issue with TT systems is that the TT electrode can itself be an source for incoming surges (e.g. nearby lightning strike), and therefore these devices are sometimes equipped with enhanced N-E protection, due to the higher risk of N-E surges.

[@e5Group]

Yes yes and yes. That SPD was knackered. Fascinating JW! 👍

[@millomweb]

Are you sure the pins you're pointing at with the screwdriver at <a href="#" class="seekto" data-time="1057">17:37</a> don't just unplug from the riser board ? (rather than as you cut them ?)

[@piratedprivacy9052]

obviously clear, they're not detachable.

[@millomweb]

@@piratedprivacy9052 So what's all the plastic bits for ? And why have P3 easily detachable if P1 and P2 aren't ?

[@piratedprivacy9052]

perhaps mechanical support for the pins... why dont you take a closer look at the video?? logic will also backup that JW not that nerd to cut those pins instead of easily unplugging them, if anyway found possible by his hands...

[@piratedprivacy9052]

and later JW did added that "are actually soldered in" .

[@jovetj]

The "plastic bits" are called a header, and they'd be helpful during the manufacturing process.

[@tutnallman]

Most interesting. thank you

[@tarassu]

Why there are different voltage levels. Like 275V and more.

[@jovetj]

Did you test the fuses at any point? What if its only failure was some blown fuses?

[@millomweb]

Noting this covers types 1 to 3 and noting there appears to be a 0 version as well (as more of my E falls off the E key) - is the 0 type surge protection simply arcking horns ? :)

[@dougvee4744]

Saw something lile this at CES in Vegas where the guy had packed the MOVs into a thin concrete mix. Fire protection I assume unless anyone knows better?

[@ickipoo]

If the surge has enough energy, the MOVs will fail explosively, and some sort of containment is usually desirable.

[@MrNormaj]

many thx John, good vid :-)

[@ingoditrustcaucasianworth8916]

Hi.Where could i get this plug in surge protection thing? There is no link for international buyers. Thank you

[@jwflame]

That cheapo orange surge protector came from a seller on Aliexpress.

[@sammaimas155]

What sort of surge protection device would be used on a Low Voltage system such 12-24 volts. I am thinking of a solar powered automatic gates an intercom system. Thanks

[@roberthawley3995]

There are devices for all types of circuits. Dehn make a very large range see their Blitzductor range

[@jeffkardosjr.3825]

A fuse can help.

[@anonnona8099]

A question, if you don't mind, and an observation. Q: How is the 10m circuit length calculated with ring finals? O: I'm not at all sure that 10m *isn't* a problem in normal houses. There are millions which don't have suspended floors on the ground floor, so g/f socket cables drop down the walls from the 1st floor void. So it's up the wall from the CU, running around under the floor, and dropping down to each socket. Or, if they are reasonably close, down, along, and back up. Ring or radial, unless there are JBs under the floor (and until *relatively* recently, with MF JBs) they were problematic. And still are really, because if it's a ring, then each socket is on a spur, which rules out horizontal runs to other ones. And even when that topology isn't needed, because there are suspended floors, again it's pretty easy to start banging up against 10m. This feeds into my question about how ring finals are measured - 5m can easily go in running up/down from/back to the CU. With the fairly common design of socket circuits split left-right or back-front instead of up-down, there are runs up and down walls all over the place. Just the perimeter of a small 8' square bedroom is pretty much 10m. I live in a regular semi-detached, not big - about 8.6m x 6.8m. The CU is on an outside wall, so up and across to a socket on the party wall is about 9m. If I had a single ring final running around all three bedrooms, including serving sockets on each side of the separating walls, that's about 38m. OK - in reality it would be less, as it wouldn't run into each corner, and there would be savings from diagonal runs under the floor, but by how much? As it's an inductance-related-to-cable-length issue, if a socket on a ring where, say, one leg is 20m and the other is 5m, will there still be a risk of an induced excursion at the socket, or will the 5m leg mean that the SPD keeps it in check? If 10m really is a problem, this problem is going to be a common one.

[@SittingDuc]

I speculate that the plastic spacers on metal springs at the bottom are to direct any arcs to the case (ground), instead of letting high voltage "jump" across the MOV from one solder terminal to the next. Same reason why they use 5-8 little disks with air between them, instead of one fatter one - because high voltage jumps :)

[@ChumpusRex]

Probably not. I think they are overload disconnectors. When a MOV element fails, due to overload or wear (closed circuit) it will heat up. The solder (probably a special low melting point solder) holding it to the PCB melts, the spring pushes the MOV and the plastic slider up, so that the MOV is no longer in circuit, and the plastic slider now becomes an isolating barrier where the MOV used to be. At the same time, the spring drives the MOV up through the plastic film with the sense wires on it, cutting the sense wire and triggering the alarm. Multiple elements are used to limit the heat in each individual element and increase the current handling capability. I had initially thought that the MOVs were series connected, but they aren't. In this case they are paralleled in groups of 6s (mostly). Paralleling MOVs is difficult because they are highly non-linear devices, so require exquisite matching otherwise they won't share the current - the most sensitive one will take the overwhelming majority of the current. It's interesting to see only MOVs in a type 1 device - the specs are written in such a way that it is extremely challenging to achieve type 1 operation with MOVs (there is, incredibly, a conspiracy theory about why this is!), even though MOVs are highly preferable to the other technology (spark gaps) available at the type 1 energy level. That said the type 1 specs on this unit are pretty feeble (6.25 kA, compared to the more standard 25 kA per mode needed for reliable lightning protection).

Do these surge protectors degrade and have they a recommended life, how often should they be replaced?

[@sdgelectronics]

Very difficult to say as yes, they degrade to some extent each time they suppress a transient. Most only indicate replacement if a surge great enough to trigger a thermal overload or fuse was present. I imagine the manufacturers would recommend to replace during each inspection.

@@sdgelectronics Thanks.

[@johncoops6897]

@@sdgelectronics - they are actually designed to fail, that's the whole point. They "take one for the team" each time they suppress a fault. This big problem is that MOVs typically fail CLOSED circuit, due to thermal runaway. When that happens, they can overheat something chronic, literally short-circuiting the normal mains some time after the surge event. I've been involved in diagnosing a few "incidents" where there has been "fires" (smoke before a breaker tripping) due to MOV breakdown. End users find it hard to understand the phenomena.

[@sdgelectronics]

@@johncoops6897 That wasn't the question. The question was how often should they be replaced which is difficult to determine unless the thermal overload triggers.

[@johncoops6897]

@@sdgelectronics - If you read carefully, you'll see that the question STARTED with "Do these surge protectors degrade" which is what I am expanding upon. The bottom line is that there is no way to know how long they last (it depends on how many and what size transients are absorbed), so nobody can recommend how long they last. You are correct that the only way to know they are dead is after they catastrophically fail (which may not have even been from a surge event). A lot of people think that a thermal overload is caused a surge, however that's not always the case. After they become "worn" (internally damaged), they sometimes start to slightly conduct at very low overvoltages, and literally melt or explode. That's because they are only capable of dissipating the heat from extremely SHORT duration pulses. Once the thermal overload is tripped, you KNOW they must be replaced, but it's almost impossible to know when that might occur.

[@alphaomega7868]

That's a 20 year old Furse unit. The new ones look nothing like that inside

[@millycarrington]

Ah the mythical 'plugsocket' lives!!

[@DrQuadrivium]

A good money spinner for the manufacturers. Whatever did we do without them.

[@dalriada842]

With its discrete design and high cost, I think I'd be tempted to source replacement components to refurbish it. Those discs look like Littelfuse Varistors. www.littelfuse.com/products/varistors/industrial-high-energy/ca/v481ca60.aspx

[@bdf2718]

I'm surprised at how narrow the tracks to the MOVs were. I know the surge is very brief, but 10KA through those??? Hmmm, deliberately fusible?

[@pau1phi11ips]

I used to work for Furse in R&D when this was made. The copper plating thickness on the PCB is nowhere near standard. We used to the 10kA test in-house and externally and they could handle the current. The assembly design in this video is 20 years old though. They weren't made like that when I left 10 years ago.

[@siamakj2008]

What happened to your finger? Be careful man!!!

[@markjohnson8390]

Sparky Marky

[@davidmarsden8868]

Wow... nearly £700

[@johnalexander2349]

£800 product replaced because a badly designed, 10p circuit board failed...

[@roberthendy9493]

P

[@millomweb]

I note the quality of this video is 1080 @ 50 fps - which I think is excessive (and causes occasional buffering issues). I think you'd find no one would notice any difference at 25 fps or even at 720p. Does anyone else have buffering issues with this video ? Even so, quality need not be quite so excessive for this typical content.

[@johncoops6897]

Nope, because KZbin automatically reduces the video res to suit each of our connections. I am watching this on an old computer via WiFi and it's playing without buffering at 480p. The content that's been uploaded 1080p or even 4K doesn't mean that's what gets served to each viewer.

[@johncoops6897]

@@Richardincancale - no shit, Sherlock! When you manually increase the resolution higher than what KZbin recommends (for you), your bandwidth may not be sufficient to maintain a reliable, constant stream. Guess what happens.... buffering! So, irrespective of whether you consider that you have a "big screen" or that "1080p is required", if your Internet+LAN/WiFi+Computer cannot process the data fast enough, you will get buffering. Reading and comprehension - you should try it.

[@millomweb]

@@johncoops6897 I agree as I know others have complained about other videos being of low quality when they're not for me - so it's settings at their end. OK then, for me, the YT auto quality setting isn't working for me at 1080 @50 fps as other videos have minor buffering issues too.

[@millomweb]

@@Richardincancale I'm watching on a 1080 screen but it's not a big one. 720 seems fine on this too for general viewing. It depends on the size of the big screen, if that's 1080 too, 720 will be fine on that too. If you're expecting a cinema type experience then higher resolution would be good but I can't see JW going into blockbusters !

[@benbaselet2026]

@@millomweb Just select the quality you want from the settings. I would hate to watch garbage video just because someone else is having buffering issues and not bothering to change the quality setting for themselves. I really do prefer a high quality video stream when we are taking a close look into a device like this. 1080P 50 Hz is the minimum in my mind these days.

[@user-ym6wr1im7j]

You talk in a most condescending manner.

[@ickipoo]

I disagree entirely, and I find your comment quite offensive and unnecessary.

[@user-ym6wr1im7j]

@@ickipoo thanks for taking time out to disagree with me sir.