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Lightning Protection on Wind Turbines

Discussion in 'Renewable Energy' started by Aloefundi, Feb 14, 2008.

  1. Aloefundi

    Aloefundi New Member

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    Howzit Guys

    I'm relatively new to posting on this list, but been around for a while.

    I've finally got most of the kit together to build my fist wind turbine, I ordered Hugh Piggott's book a while back and I'm pretty much set to get started.

    My problem is this. I live on a smallholding (approx 8.6 hect) and my house is built on a hill. No quite at the top but close enough. Living on the Witwatersrand we have one of the highest lightning strike rates in the world. This summer alone I know of 4 strike incidents in our 'valley' alone. One was our ph-angle and borehole pump. (Out of interest the others were 2 x gate motors and another borehole. All on seperate occasions / strikes)

    Now, the idea of putting up a 10-15 meter mast with a wind genny at the top to generate your own power gives me some very warm feelings about being self sustainable. Especially since we are at the start of a 7-8 year energy generation crisis in South Africa. I have a few other idea's however this is the first that I want to tackle.

    Does anyone on the list have any experience or idea's about protecting a turbine installation against lightning strikes? However this is not just about protecting the turbine, but all of the ancillary equipment connected behind the turbine as well.

    Any suggestions would be appreciated.

    Regards

    Aloefundi
     
  2. mvs sarma

    mvs sarma Well-Known Member

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    I feel it is better to call a Authenticated and qualified specialist and get it designed for the local need. I am telling like this as it is a hobby play issue and it is straight related to HUMAN LIFE. Let us learn the subject later. Mostly you find that Electrical distribution people, Telecom and Cellular Tower installers, and Radio Transmitter installers, and HAM operators are few sources who could be of help. This has to be dealt with extra care and not like radio Doctor program. Ofcourse, the wind generator supplier could suggest you standard methods of protection to property and LIFE.
     
  3. rjvh

    rjvh New Member

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    what kind of tower you have ??steel wood or glassfibre

    is it one solid one or braced with a dozen of small lines??

    verry importand is that you will have a sort of a grid system of conected ground rods in the soil how long the rods have to be is depended of your situation
    if you can hit the water level in the soil your completly ok but might be difficult in your case

    do use copper and not alumineum (aluminium will burn away and is not useful annymore copper does resist it better)

    after every hit you have to inspect the whole system again

    make sure your power cables have a good insulation XLPE cable is expensive but is great for it
    and if you have a steel tower make sure a lightning protector is solid conected to the tower and everything else what has power is insulated from the tower

    and specialized advise is always welkome so to companies that have to deal with it

    i only have some basic experiance and build a few systems but never design them
     
  4. dave

    Dave New Member

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  5. Aloefundi

    Aloefundi New Member

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    rjvh

    Thank you for your response.

    I'll be using a steel ham tower that I picked up on auction. Total length / height is 12 mt, it's triangular in cross-section.
    The bracing on the tower will be steel cables that have been recovered out of a 50pair telecoms cable. I've not quite decided on the number of brace points yet, but either 6 or 9 makes sense. ( I'll have to take into account the weight of the finished turbine)

    As for hitting the water table, it's 25 mts down at my borehole and the house is about 3-4 mts above the top of the borehole . So work on a 30 mtr drop. We are not likely to drive an earthing bar that deep. ;-)

    My main concern is a direct strike on the mast, as this will light up my battery bank quite spectacularly. Not to mention anything else that is in the way. The batteries will be housed in a seperate structure that is 5mtrs from the main house with a distribution cable running from there into the house. Additional power from PV panels (future project) will also be routed to this room. All of the required equipment will be housed in this room. Inverters, Dump load / charge regulators etc.

    I am planning on earthing all of the equipment that can be earthed in this room directly onto 12 mm (1/2 inch) copper earthing bars driven into the ground.


    Ouch, thats what I want to avoid, the idea of getting hit once does not appeal, multiple hits is not my idea of a picnic.

    Thanks

    Aloefundi
     
  6. bryan1

    bryan1 Well-Known Member

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    Hiya Aloefundi,
    You may want to check out http://www.fieldlines.com/ and do a 'google search of the board' for Lightning Protection. I did the same search but the google link in here would take up too much space and I did get over 10 pages of results. I'm sure off that search you will get the best advise from people who have been there done that the right and wrong way.

    Essentially all did on my tower was to drive in 4 copper rod's 1" diameter by 5' long and connected them together and to the tower using multiple strands of 400 amp welding cable. I did it just as an added pre-caution as I have a few high tension power towers close by and they seem to attract all the lightning. Oneday I might be lucky enough to snap a pic of a strike on 1 of the towers.

    Hope this helps

    Cheers Bryan ;)
     
  7. Aloefundi

    Aloefundi New Member

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    Hi Bryan

    Thanks for your input. I will do as you suggest and see what comes up. I'll give feedback as to what I intend doing. Just so that the bright sparks here can offer some additional advise to prevent bright sparks at home.(sic)

    Regards

    Aloefundi
     
  8. Hero999

    Hero999 Banned

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    Make sure the neutral conductor or negative side of the DC bus from the generator is as connected to the the earthed metal structure and don't use it in a storm.
     
  9. picbits

    picbits Well-Known Member

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    I'm not an expert but would it not be a safe move to erect similar sized (or taller) "decoy" towers close to the turbine generator ? That way if a lightning strike was to occur then it might prefer the shortest route to ground (i.e. the taller better grounded towers) ?
     
  10. Hero999

    Hero999 Banned

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    That's a good idea.
     
  11. rjvh

    rjvh New Member

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    not a bad idea but you still have the risk (not a small one) in case of a strike that the lightning branche off and still hit the the other tower
     
  12. Aloefundi

    Aloefundi New Member

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    Hi Guys

    I really value your input, it's much appreciated.

    I had a quick squiz on the net for lightning protection and came up with ion dissipators. They make a lot of sense. Should be pretty easy to make as well.

    Bryan, your tip on www.fieldlines.com was worth the time, and it gave me a solid direction to look in. Thank you.

    I have attached a .pdf with a pretty interesting article on lightning protection for you guys to read.

    Interesting to note that while driving around this weekend I saw a number of installations (electrical and otherwise) that had ion dissipators installed.

    I think that my mind has been made-up as to how I will go about protecting my genny. So it's a case of making sure that the whole rig is earthed as well as possible and installing ion dissipators on the top as well. There will not be much changes required in design to accomodate the dissipators at the top end.

    Thanks for the lateral thinking.

    regards

    Aloefundi.

    You will have to follow this link for the article, http://www.electro-tech-online.com/custompdfs/2008/02/RG-Pg4-May07-Ltr.pdf
     
    Last edited: Feb 18, 2008

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