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Forum Index : Windmills : Magnetic Brake
| Author | Message | ||||
| Jules Newbie  Joined: 08/05/2014 Location: AustraliaPosts: 9 |
Hi I have a 1.5kw chinese built wind turbine that has a magnetic brake. I was forced to apply the brake under heavy wind conditions and now it seems like it will not disengage. The manufacture produces a number of models and only advises the brake cannot be applied when generator is in operation for units above 3kw. Wind conditions have been relatively light but within what I would have expected to get things spinning again. Wondering what could be the possible causes for not restarting: Dose it take time for the magnetic field to dissipate. Dose it require a decent wind to brake the field and make the wire "hot" again. What damage if any is possible to the turbine. Thanks again Julian |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Julian Might need some more info. Does it still spin, with no output, or is it totally locked up? Also can you give us a make/model, or a photo. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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fillm Guru  Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Julian, Applying the magnetic brake is just shorting the phases, doing this in Strong Wind when the mill is at very high RPM and output will usually 99.9% result in a Burnt out stator , which is now permanently shorted. If it looks like one of these drop me an email and I might be able to help . 
PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Jules Newbie Joined: 08/05/2014 Location: AustraliaPosts: 9 |
Hi Phill Thanks for the advice pity they didn't put that in the bloody manual, will try and get the manufacturer to fix/replace under warranty but they can be a little difficult to deal with unless they are taking your money :( |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
@Jules, I have a 500 watt to 1KWatt wind genny and often have to shut down in strong winds. Mine is fitted with a resistive heavy duty dump load that I switch on (or automatically) to slow the mill somewhat before applying the phase shorting brake. sometimes I have to wait for a slight lull in the wind but so far have not burnt out the windings. If the lull is not enough for the brake to work, I switch it off and try again. Some times, the wind has been so strong even the above doesn't work but the dump load is enough to stop over speed and hence phase burn out. If you don't have a dump load, seriously think about fitting one. David M. |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
I have an Exmork wind gennie . I am fiddling around with a device similar to Phill's cable tail furler . My thoughts are a motorcycle disc brake disc and caliper -I have a hydraulic one and it's complete with the master cylinder and plunger/lever. I once fit a push bike disc brake to a F&P set up --it was fairly successful,so I see no reason that the bigger version should not work . Thinking of either a pull down cable to operate or a dc operated relay at the top to activate it??? Complicated, yep, but I've plenty of time and don't rely on the power ,it's just a pass time hobby for me. Bruce Bushboy |
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| Jules Newbie Joined: 08/05/2014 Location: AustraliaPosts: 9 |
Yea I have dump load but dont have a way of switching manually to slow turbine. Generator is only a few moths old and has already shed its blades. Installed a weather station so I knew when the wind speed was getting to high to avoid this and now have a burt out unit. Feeling frustrated. Here is a photo of the unit out of i 
nterest. |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Thats an image of the windings on the 2-3Kw one I've got , the wire would be probably 1mm dia, so she would be able to take a belting in the wind. When you short your windings,I'd suppose being far lighter windings ,she'd burn out real quick. I also have the instructions in my Exmork manual about throwing the "shorting" switch at high speed--it's a no-no ,in black and white. My supplied dump load is 1kw resitive coiled resistors,I guess they would be able to take a lot more than that ,they are fairly big and chunky. Bruce Bushboy |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I have changed my mind Bruce. I used to think heavy duty would handle high winds. I have seen a couple of locations that under certain conditions it is like there is a nitrous button. Seems to only happen on a few rare cold nights, I have seen it twice myself you can feel the wind change, no gusty-ness at all, more like a constant force, if the turbine is not fully parked and has no furl it just spins faster than you would think possible until something breaks or melts. I'm confused, no wait... maybe I'm not... |
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| Jules Newbie Joined: 08/05/2014 Location: AustraliaPosts: 9 |
My turbine has an automatic furler any suggestions how I could retro fit some sort of manual mechanism to this? |
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