Braking system

[nothing to lose]

All these mills and gennies being built and mine I am working on, I just thought we don't have much mentioned anywhere about a braking system!

I think I saw something mentioned about shorting out the genny will stop it. Other than this has anyone been giving much thought about what to do for repairs durring wind?  Hopefully we won't need too, but what happens if say the blade gets a bad wobble, or a wire comes loose at the genny itself, how do we stop these things from spinning so we can make a repair?

In a case of a wire breaking, we would not even be able to short it out. Just a thought that accured to me as I look at all the constant wind we been having here. Not really wanting to wait 2 hours for the wind to stop or grab hold of a spinning blade with my hands. Not hard winds, but been enough all the time it would probaly always be spinning even if not fast enough to make power.

[zubbly]

Hi!

     One possible very overlooked braking possibility is the use of a stock 3 phase motor as a brake. Of coarse this would have to be incorporated into the design to start with or adapated at some point. You simply apply DC current to any 2 of the 3 motor leads for an extremely powerful variable brake. Commonly used to stop very large rotating loads. A variable AC source ( VARIAC ) coupled with a bridge rectifier would give excellent control of braking speed and strength. When the brake is not being used, it simply would rotate with the genny.

     I might just incorporate one into one of my next projects and let you know how it works.

zubbly

[windstuffnow]

  You can climb the pole and stick your arm in the prop... that kinda' hurts though.   Shorting the alternator is much safer...

  I used to take my hand held wind meter to check Tip speed ratio's on my 20 ft turbine.  I would get just about to the tip before I'd fly off the end...  Never did get the TSR figured out....  Gave up after a few tries.... kinda' hurts... ;o)

Have Fun

Windstuff Ed

[hiker]

on mine i just climb the ladder and use a long stick to move the tail out of the wind..

[PaulJ]

   Shorting works ok in low to moderate winds, although it does stress the alternator a bit - there's a bit of a BANG! at the instant of shorting caused by the mill trying to slow down all of a sudden and the resultant precessional forces etc.

   The blades only take a few seconds at most to stall and slow to a speed where they can easily be stopped by hand.

   High winds are another story, on my mill shorting doesn't seem to alter the speed much if at all. Probably because the stator is dissipating a good portion of the power delivered by the blades already, due to its internal resistance. A more efficient/ lower resistance alternator might stall when shorted in any wind, I don't know for sure though. I'd be interested in other peoples experiences here.

   Once stalled, a shorted mill probably won't start up again no matter how strong the wind is, unless the alternator is way too small for the blades.

   I have seen cable operated furling systems which pull the tail parallel to the plane of the blades, turning the mill sideways to the wind. Of course, these could fail too.

   On one of my first windmills, I had a long rope tied to the end of the tail. To stop the machine, I simply used the rope to pull the tail around into the wind. This worked really well provided the rope didn't get caught up in the blades!

   

[nothing to lose]

OK, I guess turning the machine out of the wind works fine.

Since I am planning various setups I am trying to consider many too many points at once perhaps.

Eventually since I need storage space here and also a shed to put many of my cars in that are just sitting, I am planning to roof mount alot of gennies. To work on many of them I will be able to stand up there with them and not lower them like a tilt up tower.

Being as no-one will be in the buildings much, I don't consider noise a problem as long as it does not carry through the air like an amplifier off the metal buildings.

Basic building plan is 2" heavy wall (1/2" thick) pipe about every 10' at a height of 20'. Building itself only 10-12' high roof. I am figuring all the pipes connected to the roof and walls will make them self suporting at that hieght and only have to guy wire the sides and corner pipes to the ground. The rest of the pipes can be guyed to the roof or each other for higher support if needed and save alot on cables!

Basically I am wanted it as self supporting as posible of course.

As for a shed for junk storage, I figure about the same thing but only a 10'x10' shed, 20' posts.

As I fill all the posts with gennies I should be able  to produce tons of power, and of course I also figure I will be making tons of repairs to things I messed up will building them. With this type setup I can stand on the roof or make a ladder and mounts to work on them in the air safely, putting up, taking down, changing wires, ect..

I didn't really want to do as windstuff suggested and stick my arm in them to stop them