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Re: [s-w-h] Re: About my lightning strike

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  • Darryl Thayer
    NIce Job Rob This is a good education in lightning. Everything you say is consistant with my experiance and explanation, thanks.  I only had an idea that
    Message 1 of 10 , Sep 30, 2008
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      NIce Job Rob
      This is a good education in lightning.
      Everything you say is consistant with my experiance and explanation, thanks.  I only had an idea that lightning had these current levels and voltages. It is easy to see how when finding many paths to ground conductors and equipment can be effected anywhere in the structure.    It appears that stand alone towers are a better target than towers where the power lines are near. 
       
      It apperas from experiance that a very good surge arrestor of the varistor type should be able to bind the building conductors together preventing damage to interior circuits.  The analysis seems to say GROUND the tower extreamly well.  Where I always will have a ground water table in the desert it may be to low to find, and other methods sucn as Faraday  cage. 
       
       There are a couple of aspects I did not see expressed, 1) the Faraday cage effect that could help prevent damage if considered in the construction phases.   and   2)  it mentioned the fall of potenical method but not the induced current method of ground testing.

      Darryl
      --- On Tue, 9/30/08, Rob Beckers <Rob@...> wrote:

      From: Rob Beckers <Rob@...>
      Subject: [s-w-h] Re: About my lightning strike
      To: small-wind-home@yahoogroups.com
      Cc: wind4energy@...
      Date: Tuesday, September 30, 2008, 6:59 AM






      Mike, I looked into lightning and lightning protection for wind turbines
      some time ago. Wrote a few Web pages about my findings as well. Anyone
      that's interested, see http://www.solacity .com/Lightning. htm

      Rob
      -/-

      Solacity Inc.
      Phone: (613) 686-4618
      Fax: (613) 686-4622

      -- This message was entirely written using recycled electrons --
      All about the 6 kW Scirocco wind turbine at www.solacity. com
      Join the Green Power Talk forum at www.greenpowertalk. org
      ------------ --------- --------- --------- --------- --------- -

      --On September 29, 2008 11:54 PM +0000 small-wind-home@ yahoogroups. com
      wrote:

      > 2a. About my lightning strike
      > Posted by: "Michael Klemen" wind4energy@ yahoo.com wind4energy
      > Date: Sun Sep 28, 2008 7:55 pm ((PDT))
      >
      > It appears that my lightning strike either came
      > in on the ground wire or on the negative wire
      > of one of the turbines (which is tied to ground).
      >
      > Anybody who knows lightning care to comment?
      > Lightning arrestors always go back to ground,
      > so it seems like if lightning strikes the ground,
      > there's nothing that can be done to protect against
      > it.
      >
      > I have a class T fuse, which I believe (I am wishing
      > I had looked at it again) is between the turbine
      > and the inverter on the negative leg...so it doesn't
      > appear to have been current-induced. ..which would
      > lead to a voltage surge on the ground wire...
      >
      > This one has me baffled. But all three turbines
      > are back up and running...as well as my other inverter.
      >
      > Mike


















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    • Rob Beckers
      --On September 30, 2008 7:24 AM -0700 Darryl Thayer ... Thank you! Quite a bit of time and effort went into gaining a better
      Message 2 of 10 , Oct 1, 2008
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        --On September 30, 2008 7:24 AM -0700 Darryl Thayer <daryl_solar@...>
        wrote:


        > NIce Job Rob
        > This is a good education in lightning.
        > Everything you say is consistant with my experiance and explanation,
        > thanks. 

        Thank you!
        Quite a bit of time and effort went into gaining a better understanding of
        lightning and lightning protection. There is a great deal of conflicting
        (and misleading) information on this topic out there.

        > I only had an idea that lightning had these current levels and
        > voltages. It is easy to see how when finding many paths to ground
        > conductors and equipment can be effected anywhere in the structure.

        Indeed, grounding structures doesn't mean they are at 'ground' potential
        during a strike: For well-grounded towers the expectation is around 1,000
        Volt for every foot in height. So, taking the turbine leads off the tower
        at 3 feet from the ground means you just created a 3,000 Volt differential
        going into the batteries/inverter, when lightning hits the tower.

        >    It
        > appears that stand alone towers are a better target than towers where the
        > power lines are near.   
        > It apperas from experiance that a very good surge arrestor of the
        > varistor type should be able to bind the building conductors together
        > preventing damage to interior circuits. 

        Most varistor type devices can't handle full-blown strikes (ie. a 10/350
        device to use the parlance). They are mostly for residual voltages/currents
        (8/20 devices in other words). A possible exception may be the Delta surge
        arrestors, these are silicon oxide varistors; they are not the greatest
        surge arrestors, but they can handle the currents for most strikes. Their
        downfall (for the Delta's) is the pass-through voltage; it's far too high
        for most electronics to survive. Now, these days inverter manufacturers put
        MOVs at the inputs of the electronics, and if you get lucky (sufficient
        inductance between the Delta and the inverter to decouple the two
        arrestors, and a strike that's not too powerful) it may just be enough to
        have the electronics survive.

        There are varistors that can handle the currents involved in a direct
        strike, but they are large and expensive. Manufacturers of arrestors use,
        for the most part, some type of spark gap device for that purpose. More
        robust, and cheaper. Except for combo-devices those direct-strike arrestors
        have a too high pass-through voltage to protect electronics. A second
        (down-stream) device is needed (and sometimes a third-level device) to get
        voltages down to manageable levels. There are combo devices that put those
        in a single package, for example, Dehn makes them. Not cheap though.

        > The analysis seems to say GROUND
        > the tower extreamly well. 

        Anything you can divert to ground means less energy to deal with for the
        arrestor/electronics. Grounding is definitely the no. 1 thing that can be
        done to prevent damage. Still it's important to keep in mind that not all
        ground is ground when it comes to lightning; during a strike the currents
        are such that ground potentials can vary by many kV's from one place to
        another (causing currents and voltages to go places where they will kill
        electronics if nothing is done).

        > Where I always will have a ground water table
        > in the desert it may be to low to find, and other methods sucn as
        > Faraday  cage.   

        Take a look at the Ufer ground. This was developed during the 2nd world war
        specifically to ground structures in sandy, poorly conducting soils. Very
        effective, and cheap to do if you plan for it at the construction stage.

        Faraday cages are expensive and normally overkill. From what I've seen they
        are not normally used for commercial installations that require hardening
        for lightning. Using proper grounding, wiring, single point ground, and
        surge arrestors can make things virtually lightning-proof (that is not
        cheap either though).

        >  There are a couple of aspects I did not see expressed, 1) the Faraday
        > cage effect that could help prevent damage if considered in the
        > construction phases.   and   2)  it mentioned the fall of potenical
        > method but not the induced current method of ground testing.
        >
        > Darryl

        I've not looked into ground testing much. The intend was to give people an
        idea of how lightning does its damage, and what can be done to mitigate
        that. Preferably with the means available. If those pages can help with
        that I'm happy! :)

        Rob
        -/-

        Solacity Inc.
        Phone: (613) 686-4618
        Fax: (613) 686-4622

        -- This message was entirely written using recycled electrons --
        All about the 6 kW Scirocco wind turbine at www.solacity.com
        Join the Green Power Talk forum at www.greenpowertalk.org
        -----------------------------------------------------------------
      • Richard Averett
        According to their test data, the unit will produce about 2,000kWh per year in a 12 mph breeze. http://mariahpower.com/index.php?option=com_content
        Message 3 of 10 , Oct 1, 2008
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          According to their test data, the unit will produce about 2,000kWh per year
          in a 12 mph breeze.



          http://mariahpower.com/index.php?option=com_content
          <http://mariahpower.com/index.php?option=com_content&task=view&id=47&Itemid=
          72> &task=view&id=47&Itemid=72



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        • Darryl Thayer
          Hi Good, but has anyone got one and how much power is it producing? Darryl ... From: Richard Averett Subject: [s-w-h] Mariah Wind
          Message 4 of 10 , Oct 1, 2008
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            Hi
            Good, but has anyone got one and how much power is it producing?
            Darryl

            --- On Wed, 10/1/08, Richard Averett <averettr@...> wrote:

            From: Richard Averett <averettr@...>
            Subject: [s-w-h] Mariah Wind Power VAWT
            To: small-wind-home@yahoogroups.com
            Date: Wednesday, October 1, 2008, 8:07 AM






            According to their test data, the unit will produce about 2,000kWh per year
            in a 12 mph breeze.

            http://mariahpower. com/index. php?option= com_content
            <http://mariahpower. com/index. php?option= com_content& task=view& id=47&Itemid=
            72> &task=view&id= 47&Itemid= 72

            [Non-text portions of this message have been removed]


















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