Surge Protection and Arc Fault Detection

[RSin]

There's two types of protection for the system over and above the usual RCD, RCBO type stuff.

1) Surge Protection - protecting against power spikes or lightning strike coming through the supply

2) Arc fault detection Device (AFDD) - in case the insulation deteriorates on cables or something comes loose etc.

First question is whether this is really needed...i don't plan on setting up any life-support clinics!

if yes, what, and where e.g. between the meter and isolator in consumer unit or after the circuit RCBOs?

UK Based.

cheers.

[Rob_in]

Hi,

Funnily enough we suffered a lot of damage* on Friday night (Friday 13th would you believe!) from a lightning strike, so the answer to #1 below is absolutely! I have ordered a Type 1+2 surge arrester which will be fitted ASAP. The cost of the surge arrester is significantly less than the damage (getting on for 10x less).

FWIW, all the circuits in the house were protected by RCDs and every one of them tripped, but clearly not in time to stop the surge (surge arresters allegedly have a much faster reaction time).

Robin

*Damaged gear - just to show it's rather random what gets hit.

- Miniserver (KNX/Ethernet dead).

- Daikin Altherma heat pump (water circulation pump had an exploded chip inside).

- All 5 of the EldoLED controllers installed.

- One of the motors in our HVAC system.

- Legrand Smart energy meter.

*Stuff that survived

- ADSL Modem.

- WiFi router (Miniserver & Smart energy meter were plugging in this but it's fine).

- KNX PSU (even though the KNX input on the Miniserver seems fried).

- All the rest of the KNX gear.

- Loxone extensions (1-Wire, ModBus, DMX).

- TV, HiFi, dishwasher, washing machine, etc, etc.

[Deac99]

I am now on my 4th miniserver, 2nd 1-Wire extension, 3rd modem, and countless modems and access points in the last 7 years.

The first miniserver was lost with a lightning strike when I had lightning rods etc, no surge protection in my electrical cabinet but the Loxone was getting power from a surge protection strip.  After that I got surge protection in the main cabinet.

The second was lost when a series of problems occurred and ultimately a pressure relief valve that was not properly installed sprayed water all over the heat pump which ultimately shorted out multiple boards and in the process created a surge and took out the miniserver which was still on a surge protection strip.

The 3rd was lost after another lightning storm - I sent it back to Loxone and asked if they could identify exactly what got damaged, they took a photo and said the surge came in through the ethernet port and blew the chip off the board.  Like Rob_in says, it is somewhat random, that storm I lost a router, an access point but that time the modem and other access points were just fine.  I also beefed up all the cat 6/7 cable grounding and made sure all the shields were grounded at the cabinet side.

Since then I found these and have now installed them at both ends of all critical devices on the network.  I was a bit concerned with what they actually are so I took one apart - they are solid state surge suppressors (not gas tubes).  It looks to me that when they fail you will know because there will be no network connection.  I also did 5 speed tests  with it installed and 5 without it installed and there is no degradation in internet performance.  These devices have only been installed for about 4 months so no particular opinion as to how effective they are.  

https://www.aliexpress.com/item/YOC-Hot-Sale-RJ45-Plug-Ethernet-Network-Surge-Protector-Thunder-Arrester-100MHz/32689525808.html?spm=a2g0s.9042311.0.0.33704c4doPzkcA

All that being said, I am essentially on top of a mountain and we do get some bad storms here.  I think a normal home would not have nearly the problems I see.  I've been throwing everything I can find at it as it has been getting somewhat expensive.

[RSin]

Wow! ok you've convinced me I need it ...and Deac we need to see some photos of this mountain top bond-villain hideout, sounds great!

So where do you fit the device?

I think you fit a type 2 at the incoming after the meter - that protects the supply side.

What about the ethernet issues, is it possibly coming down the telephone cable or is it bouncing around through all the earthing?

(which makes me think of the question I posted on the cat cable shielding thread - my electrician wondered whether we should be earthing the cat cable to the same bar as the 230v)

How does a type 1+2 device work? Type 2 is for most domestic appliances, type 1 is loxone, network etc. You need the higher type 2 so you don't get nuisance tripping, but then how does the type-1 part let normal voltage through. I've read a fair bit but no-one seems to have both normal & sensitive equipment and where to install what. Its either you have one or the other!

cheers guys.

[RSin]

The plot thickens...doesn't it always. The 'types' can be a little confusing as in the SPD docs they often talk about equipment groups and type.

Don't get confused like me! the types go up in sensitivity and the equipment groups go down in sensitivity!

anyway... good docs here:

https://new.abb.com/low-voltage/products/system-pro-m/surge-protective-devices-ovr/spd-class-2

http://www.beama.org.uk/asset/1FE338CE-4969-4B56-9637F3DEA6C683C6/

[Deac99]

Wiki is a good source for understanding how the various SPD's work.    https://en.wikipedia.org/wiki/Surge_protector  

I have protection in my main cabinet similar to the ABB ones that you posted, I have expensive MOV SPD's protecting my heat pumps (I think they were around 140 Euro each).  The Ethernet protectors are the Transient Voltage Suppressing Diode type - basically a Zener diode that when an overvoltage happens it is shorted to ground.  The beauty of these are that if it is a large overvoltage it just blows the diode so the other side is isolated and the protection is fail safe in the sense that the equipment is protected but you will no longer have ethernet until you replace the device.  This is how the properly designed MOV's work as well.  On my heat pumps for example if the MOV's are blown it will short and actually trip the breaker.  If I go to turn the breaker back on and it trips immediately, that would be the first thing I would check.

As far as how did the transient get into my Ethernet line - good question.  I don't believe it came from DSL because the initial modem/router was continuing to function perfectly.  My son is an electrical engineer working for ABB and specializes in grounding protection for substations in the power grid.  His theory is that since I have Ethernet lines that are extremely long (several that are over 100M) his belief is that all it would take is a fairly close lightning strike going somewhat perpendicular to one of my long lines and the line would act like an antenna and pick up a large surge just from the radiation of the lightning - it would not have to be a direct hit to cause this.  

I've actually gone so far as to wrap each 1-Wire sensor through a double ferrite coil as well as the end of the line that connects into my 1-Wire extension.  The wrap will suppress any high frequency transients.

I did talk to the engineer that works at a ski slope across the valley from us, he chuckled and said that even with all the suppression systems they have they still lose servers and equipment each year, you just do your best.  They do not have Ehternet problems like me anymore because they switched everything to fiber.  I don't think I'll go that far.

But again - keep it all in perspective Living on a mountain is pretty sweet but it comes with it's own headaches.  I point to the trees on the North side of the house and ask my friends which ones do you suppose have been hit by lighting - there are a half dozen of them with the tops blown off.  In a normal village the storms would not be nearly as bad.

On Wednesday, July 18, 2018 at 2:09:14 PM UTC+2, RSin wrote:

[RSinn]

How did you size the SPD on the mains?
Is there a calculation?

[Rob_in]

On Thursday, 19 July 2018 07:29:31 UTC+2, Deac99 wrote:

The 3rd was lost after another lightning storm - I sent it back to Loxone and asked if they could identify exactly what got damaged, they took a photo and said the surge came in through the ethernet port and blew the chip off the board.

I replaced the Miniserver yesterday and looked inside the old one. There was no obvious physical damage at all. Is it really worth sending back?

TBH, I don't see how it could have been damaged through the ethernet port because the router at the other end of the cable was fine. The KNX PSU was also fine.

FWIW, today we received new LED drivers so replaced those. All our LED downlights work fine, except for one. Just one got hit... completely bizarre! 

Robin

[Deac99]

@RSin - I can't help much on sizing SPD for the mains.  At the time I was just switching my mains from old Siemens ceramic fuses and old power meter from the power company to modernize to the latest in arc fault breakers etc.  It all consists of 2 full industrial cabinets and I had a company build it up with terminals at the top for me to connect my end to.  I just told the company I wanted good surge protection and they spec'd it all out.  But - Dehn is a leader in surge protection.  They guy from the ski area turned me on to them and he said that when ever they have questions or issues they just call Dehn and they will provide support and recommend which product would be best.  I'd try to contact them:  https://www.dehn-international.com/en

@Rob_in - I think it would be worth sending the miniserver back to them, for me it was only a few euros for shipping.  I had contacted Loxone support via a ticket (much easier than waiting on the phone as I was in no urgent rush) and asked them if they would evaluate my dead miniserver and advise on what exactly failed and their opinion on the reason.  They did that free of charge and it got me (hopefully) a step closer to increasing my reliability.  If you do I'll definitely be interested to hear the cause as well.

On Wednesday, July 18, 2018 at 2:09:14 PM UTC+2, RSin wrote: