value of fuse for stator?

[GoVertical]

Greetings, I start fabrication of a new PMA. I am using 18 AWG for the coils. I would like to add a fuse at  the PMA output. What should the valve of the fuse be to prevent damage to the stator? Comments welcome. Enjoy the day.

[TomW]

Beware of a light fuse that could blow and let your turbine freewheel. This could be fatal to the turbine.

Personally, I don't have any fusing between turbines and the battery.

If I were to fuse the line it would be for a value well above the expected amperage from the turbine and low enough to pop should a short occur in the line  on the battery side of rectifier and open before the cable overheated.

In my system with 00 Al drop cable and up to 140 amps from the turbines I would fuse at 200 amps if i were to fuse. In fact I would use a breaker rather than a fuse.

Just from here.

Tom

[wooferhound]

If the fuse blows then you will probably be experiencing very high winds, the turbine will become unloaded and spin out of control, possible even breaking up and destroying any dogs, windows or people nearby.

If the fuse doesn't blow, it may burn up the stator.

[GoVertical]

http://en.wikipedia.org/wiki/American_wire_gauge#Table_of_AWG_wire_sizes

Hi, the reason I am asking is because the wire chart gives a max current value of 14 amps  and a fuse value. I am experimenting with a mutli blade Savonius configuration. It is low RPM with high torque. I am planning on a road test and I would like to try to find the high end output but I would like to avoid damaging the stator. If I blow a fuse and the VAWT does fly apart I think the flying pieces would not harm anything.  I just do not want to harm the stator.

[wpowokal]

For the test you describe I would use a 20A fuse, the tables you are using are for cable runs and don't make allowance for wind cooling, that said I would suggest a temperature sensor would be of more help than a fuse.

Secondly while I don't know where you will be road testing but for such a small car I would add a caution, sudden cross winds from some source or other, ie truck passing, may well send that car out of control, not to mention where you have it mounted may make the steering light, with power steering you  may not notice until you have no control. Then you would have identified all of the above when you wrote your JSA, didn't you!

Allan of the jungle

[rossw]

If the fuse doesn't blow, it may burn up the stator.

... and go open circuit, thus unloading the mill and letting it run away to self-destruction!

Damned if you do and damned if you don't!

[wooferhound]

I have seen other members talk about wind speed when doing road tests. They say that the wind speed on the turbine will be higher than your speedometer reading.

[GoVertical]

Hi, I used a truck once and I road in the back and used a hand held anemometer and the wind speed on the hand held unit was the same as the speedometer on the dashboard.  It was a very claim day. It is good for ball park numbers.

[ChrisOlson]

Generally, fusing the output of a wind turbine is a bad idea.  Heat is what damages a stator and a fuse only provides over-current protection.

Say you build a generator with a max continuous rating of 50 amps.  It will handle 100 amp surges with no problem.  So you fuse it at 100 amps.  But you get good wind and run the generator at 40-60 amps for several hours.  The stator is hot.  You get a wind gust that pushes it up to 75-80 amps.  You blow a coil and drop a phase - but the fuses won't protect it.

There is only three ways to prevent damage to a generator stator

• Proper cooling
• Use adequate winding size
• Use a properly designed power limiting system on the turbine to prevent stator overheat in high winds

--
Chris

[ghurd]

This could be helpful,
http://fieldlines.com/board/index.php/topic,145653.0.html

It applies to VAWTs like yours too.
It was a long time ago, and probably lost an upgrade or 2 ago, but there was a post about a VAWT similar to yours.
His wife was ready to go shopping, and he was working on the VAWT, meaning they went shopping.
He rested it against a snow pile.
Storm came in while they were gone.
Unloaded VAWT got spinning so fast the PVC blades exploded.
Blown fuse means unloaded.
G-