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old mate's mate Newbie Joined: 11/08/2010 Location: AustraliaPosts: 15
Posted: 11:00pm 13 Sep 2011
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Team, Salutations ...
My F&P windmill is of the 7 phase flavour (New magnet rotor, old stator) and the power is rectified to 12V DC on the mill itself. I have two DC wires hanging down, they wrap, it's a worry, so I am thinking of building a set of SlipRings to transmit the DC down the tower.
Has anybody tried using the tower itself to transmit the negative line and having a single slip ring for the positive ?
Any suggestions or comments appreciated
Thanks
OMM
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566
Posted: 02:50am 14 Sep 2011
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old mate's mate
Hi,
Bearings will suffer from arc burns. Bearing grease is an insulator and will cause arcing at the tower head.
in a couple weeks or less the bearings would have to be replaced.
However a slip ring could be connected to the Tower and save a length of wire.
---------- Cheers, RoeTime has proven that I am blind to the Obvious, some of the above may be True?
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 05:42am 14 Sep 2011
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Hi old mates mate
I use a bungee tied to the tail as it lets it rotate several turns in each direction without wind up.
All the best
Bob
Foolin Around
Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190
Posted: 08:12am 14 Sep 2011
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Hi OMM,
Apart from the almost certain damage to the bearings, the problem with using any part of your support metalwork as a DC conductor is that you will encourage electrolytic corrosion. Small currents in wet conditions can shift an incredible amount of metal given a long enough time.
The other consideration is voltage drop. Any high resistance connection will dissipate a lot of energy - especially with the higher currents that apply with a 12V system. Even slip rings will typically have about 0.5V drop across them, so you are much better off not using them and grappling with cable wind-up if you can. This can be helped by having as long a length of (heavy) cable as possible free to twist, and maybe also using Bob's bungee idea, or at least a trailing rope from the tail that lets you keep track of the wind-up, and lets you walk the twist out of it in calm weather.
RegardsDon B
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:22am 15 Sep 2011
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That idea deserves a Nobel Prize for wind power innovation.Cheers, Tony.
Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190
Posted: 07:46am 15 Sep 2011
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Hi again OMM
One further point that I should have made against trying to use your tower as one connection to your wind generator output is that your DC system negative should only be connected to ground at one point - usually somewhere near your load.
If you have the negative connected to ground at more than one point, then some current will travel into the ground via one earth, and back out again via another, and again you have set the scene for some electrolytic corrosion. The higher the current in your system, the more corrosion you will see - even on unrelated things such as adjacent metal water pipes.
I don't know what the foundations for your tower are like, but your tower should be earthed in some way at its base for safety in case it gets hit by lightning. If your DC negative is also connected to ground in some way at the load, then you will most likely see some corrosion if you try to use any part of the tower structure as a DC conductor, or even if there is a deliberate or accidental connection between the tower and the negative conductor.
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