Lightning protection

[97fishmt]

Hello,
My last lightning storm had my Trace C-40 controllers
( 2 in dump mode) going into fault mode more than once.

I have been working on grounding and now am looking at
the delta lightning arrestors. It looks like the one I need is
the LA303 for my 3 phase alternator ( wind turbine).

Does anyone have an opinion on these units? Or a better solution?

I would probably also get the LA302 for the solar side of my system.

Thanks for any input,  My system is safer than ever now, except
for these voltage spikes and stray and static buildups.

Mike

[Tritium]

I use the LA-302's for my solar. I am about to get the 3 phase version to protect my irrigation and house pumps that are 3 phase 460 vac. No issues with spikes on the solar side at all.

Thurmond

[DanG]

I'm not saying those are good or bad but need to remind that lightning protection has a finite service life of X cycles at Y surges that varyies with severity. Some ancient surplus old stock items may even have a shelf life, new and unused is good.

I studied making up a canary-in-the-coal-mine add-on circuit so I could tell when near-misses had/were fatiguing the real lightning arrestors.

Some of the surplus two, three line gas discharge tube style telco/network models fail by throwing a hard fault so service techs can test and or swap out the whole circuits electronics to avoid future down times. Detecting an incident without actual protected circuit interruption by a small shunt circuit blowing a fuse might offer some reassurance.

[97fishmt]

I'm sure the old spark plug circuit from
Mick Sagrillo would keep the bugs out,
I mean the real nasty stuff.

Just wondering what others are doing.

Conduit and burying the cables was probably
the response I was I was anticipating.

My lattice tower lets the cables be exposed
not like the pipe towers we see here, where the
pipe acts like the conduit to shield the cables.

[B529]

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P7272-ND

I'm in a high lightning area, we live at 10,000', very exposed.  I've yet to have any lightning damage.

1st line of defense is a solid ground plain, everything AC and DC grounded together. I have somewhat of a grid of ground rods and grounding points (well casing), a 30' diameter buried loop around the base of my tower. Internet feed, satellite dish/cable..... everything is bonded together.

My 2nd line of defense is to use voltage specific , MOV's. The link above is what I use on all my DC stuff. Also have similar MOV's on each leg of the 3 phase turbine.

What I never understood about using the Delta type arrestors is they are not voltage specific, one size fits all voltage systems?

How's your system grounded?

[97fishmt]

Thanks for replying B529,

That's why I put this up  because
there unit is rated for 230 volt and I
couldn't see how that unit would conduct
the transient surges to work with my 12 volt
system.

Grounding for me is a problem, solid rock.
I'll take your advice on a circle around the
tower, I have heard that before and actually
around all things you want grounded.

I'll try to educate myself on the MOV's,
any hints on where to start?

Thanks
Mike

[joestue]

Mov's conduct within nanoseconds.
Although it would not be the smartest to put 230 volt movs (probably 660v clamp, as its common for most "surge" protectors to use 330 volt units on the 120 line) on a 12 volt system; if the movs can withstand a direct hit, and i think a properly designed system will not require more than a hand full of them, assuming that the current falls to zero within 500us and your 12 volt transmission lines are relatively long, it is quite possible that there would not be enough energy transmitted in that first 300us to blow all your 12 volt stuff.
But this is all dependant on the quality and quantity of the filter capacitors, where the load connects to the batteries, and how and where everything is connected.

I have said earlier that it isn't practical to make your system lighting proof but i no longer believe this to be the case, provided you are willing to spend the money on quite a few ground rods, air core line inductors and spark gaps, and the higher the system voltage the easier this becomes.

[Rob Beckers]

I've tried to write up the engineering consensus on lightning, grounding, wiring, and surge arrestors. The Delta arrestors are discussed in there as well. They are certainly not the greatest in surge arresting, however, they do provide a real level of protection for large surges at a very low price point. It helps that they are cUR listed, so electrical inspectors have no issue with them. Anything better will be 2 (or more) orders of magnitude more expensive, taking you to the pro arrestors like those from Dehn etc.

Since MOVs are mentioned, they really are meant for a different purpose. They will do a better job for small surges, while providing a much smaller pass-through voltage, good for protecting electronics. Most quality RE electronics will already have MOVs build into them. An MOV, even a large one, will not handle anywhere near a direct strike.

Good surge arresting requires a layered approach; with heavy-duty arrestors up front to short the bulk of the surge to ground (and keep wiring plus ground all floating at about the same surge voltage), and MOVs or similar devices down the line to lower the pass-through voltage to a level that is acceptable for the electronics.

-RoB-

[OperaHouse]

If you look at MOV specs, performance is measured with less than half inch leads.  The best grounding and shortest direct leads are required for them to be effective.  Adding inductance after the move will force it to take the ground path.  I know a guy that installed two way towers.  He tied several knots in power cords.  He said the cords would blow out just before the knots.  Jist an example of what a little inductance can do.  Wrapping wire around a one inch or larger pipe would be very effective.  Then some large caps that you could sacrifice in an event.  That DELTA MOV may prevent a fire but it certainly won't save the equipment.