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Old 03-05-2020, 09:11   #1
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How to find straycurrents in alternator, solar panels and wind turbine

I found some corrosion on the rigging which might be due to straycurrents. I started to look for a source to the problem and I have used Boat owners mechanical and electrical handbook as a guide. I have no silver reference electrode and I don't think I can find it for a while. I don't either have e multimeter with a higher accuracy than 10 mA. I have therefore tested resistance in the electrical system and fixed everything with a resistance of less than 40 k ohm between electrical equipment which should have infinite resistance.
Now it's just alternator, solar panels and wind turbine left. How can I check this? Is it possible without a high accuracy amp meter or silver reference electrode?
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Old 03-05-2020, 17:01   #2
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Do you have a picture of the corrosion? It's unlikely to be electrical as it's not immersed in an electrolyte such as salt water.
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Old 04-05-2020, 02:40   #3
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Re: How to find straycurrents in alternator, solar panels and wind turbine

I don't have any pictures now, but a rigger said it's risk for that the corrosion is due to stray currents.
It does not matter if it's stray current this time. I check it each year, but so far I have not done anything with the productionsunits since I don't know how to do it.
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Old 04-05-2020, 03:22   #4
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Testing Corrosion Protection Systems ~ Fluke
http://assets.fluke.com/appnotes/ele...r/B0269b_u.pdf

I'd guess Crevice Corrosion.
Crevice corrosion is actually a form of galvanic corrosion, but involves only one metal. A portion of the metal (in the crevice) becomes active (less noble), due to loss of oxygen, while the remainder stays passive. If electrolyte is present, a galvanic couple is formed and the active metal is converted to ions and enters the electrolyte solution.
Keep your rigging oxygenated (don't tape turnbuckles etc), and dry (good luck).
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Old 04-05-2020, 08:34   #5
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Re: How to find straycurrents in alternator, solar panels and wind turbine

@Gord May #4

Spot On!
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Old 04-05-2020, 09:52   #6
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Hi


No tape; try anti snag covers for turnbuckles so avoiding sail repairs, and spinnaker guys and sheets catching.


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Old 04-05-2020, 13:03   #7
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Then is the question: Trust a professional rigger who have seen the boat or the knowledge from several people here. It seems from you like if here is no rush to search for stray current and I can wait until I buy better equipment.
I think I need to tell the background to this problem.
I changed all stays less than a year ago. Recently I found some rust and that some strands were broken in the bottom of two lower shrouds The rust was in the bottom where the wire goes in the swage, but also some higher on he wire. It's no tape around. It looked like the rust on the first closeup picture on this page: https://www.boatus.com/seaworthy/mag...at-rigging.asp
I prepared myself for complaining on the riggers who did the job and got another rigger (I was in a new place so I could not take the boat to the same riggers) to check it. He said it was probably stray current and he changed those stays.
I just came back down from the mast and now there is a broken strand in the top on another of the lower shrouds. This time without any sign of corrosion.
There are sometime a collection of water on the lower swages, but it should not be that on the ones in the top, it's turned upside down.
Seems like if I have a big and expensive problem which I must find a solution on quick.
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Old 04-05-2020, 13:33   #8
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Re: How to find straycurrents in alternator, solar panels and wind turbine

I recommend this for a first step: https://www.amazon.com/AstroAI-Multi...8624131&sr=8-8
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Old 04-05-2020, 13:37   #9
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Arrandir
I am a corrosion technician. For stray current to occur all of the following elements must be in place:
1. An electrolyte.
2. An anode.
3. A cathode.
4 A source of current in contact with the anode.

It is very unlikely that these elements exist in or around your standing rigging.
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Old 04-05-2020, 13:49   #10
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Do you have any wires connected to the chainplates of those lower shrouds, maybe for lightning protection? I would guess not, so why do you suspect any ground current present? Your problem may be just a batch of bad SS wire. There is no way you should have a broken strand in any of those wires after such a short time. Unless the rigging has been flexed a lot. To me it sounds like the rigger has made up a story to account for him either not understanding or maybe, worst case, using sub-standard wire.
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Old 04-05-2020, 14:36   #11
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Nothing is connected to the rigging, but is not the definition of stray current that the electrons find a new way somewhere?
The reason why I suspect stray current is that the first thing a rigger with good reputation said was that it's probably stray current.
A multimeter with higher accuracy is on the shopping list.
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Old 04-05-2020, 14:45   #12
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Swaged rigging? I bet it's a combination of substandard ss wire and bad swaging technic. Change for swageless terminals.
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Old 04-05-2020, 15:14   #13
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Re: How to find straycurrents in alternator, solar panels and wind turbine

@Arrandir #11
Re-read #9. All four components must be present for stray current to occur. There has to be a circuit. Electrons flow in metal, ions flow in electrolyte. Where positive ions leave the anode into the electrolyte, the anode suffers material loss.

Highly unlikely in the scenario you have described.
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Old 04-05-2020, 16:39   #14
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Quote:
Originally Posted by Arrandir View Post
Nothing is connected to the rigging, but is not the definition of stray current that the electrons find a new way somewhere?
The reason why I suspect stray current is that the first thing a rigger with good reputation said was that it's probably stray current.
A multimeter with higher accuracy is on the shopping list.
Stray current is a rather imprecise term used when you don't know the cause. Any current needs a conductive path, though it can be a fairly high resistance path like salt water. The shrouds would not usually have any such paths for current to run, unless deliberately grounded by wiring.

Current needs a voltage pushing it. When you get a multimeter, you could disconnect the shroud from the chainplate and measure the voltage between those points. Really ought to be close to zero, indicating no possibility of current flow along that shroud. Also switch to lowest current range and see if you detect current. Try this with your dock power on and connected to your battery charger, if you use dock power, and with any mast-mounted running lights or other electrical items on the mast, turned on.
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Old 04-05-2020, 20:57   #15
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Re: How to find straycurrents in alternator, solar panels and wind turbine

Could there be a faulty electrical connection to equipment mounted on the mast such as mast head light, steaming light etc. Resulting in a stray current?
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