PMA high volt hazard

[mikef]

Spinning PMA's can produce voltages high enough to break down insulation.

Load resistors that won't blow out are needed for safety.

[Jerry]

I've mesured my SW-403 in very high wind with no load. Its a 48 volt.

By your example it should do 12,000 volts under these condition but all I could get was 156 volts.

O well maybe it'l work on mars?  I'll let you know when I get there? LOL?

                       JK TAS Jerry

[TomW]

mikef;

I have to jump in with Jerry on this one. I have several mills and have never seen any voltage with or without a load in any wind exceed 200 volts.

Can you site a document, some calculations, or is this just something that came to you in a dream?

Or were you personally observing these voltages on a mill that you own. Details, man.

Fantastic claims require fantastic proof. I can see the knees jerking all over the planet.

Cheers.

TomW

[Gary D]

Am I wrong here or not? If there is no load, there is no heat buildup? My thinking has been clouded recently by varnish fumes and false assumptions, but I think this is so... please correct me if I'm wrong   Gary D.

[Electric Ed]

I think he may be referring to his "glider power project". :-) :-)

Electric Ed

[mikef]

I worked on  12v regulators for pma's used for homebuilt aircraft.

The voltage is dependent on rise time of the wave, sturation, etc.

Insulation breakdown was at 3000 rpm on a 6pole pma.

[RatOmeter]

1. insulation breakdown is a real and known phenomenon.
   
2. 90% or more of all PM alternators for wind applications will never see more than triple digit RPMs in a real operation.
   
3. If someone wishes to really test the limits of a PM alt's capabilities and spin it up that fast, your original point is quite valid.  That might be something to watch out for if you stick a PM alt on an IC engine or such.
   
   

Personally, I'm not much interested in the output of an unloaded generator of any sort. By definition, it's not doing anything but using energy in that state

-RatOmeter

[mikef]

Any voltage you don't know about is a hazard.

A snubber will allso protect diodes and regulators.

Its just good design. NOT A RANT

[nothing to lose]

"Any voltage you don't know about is a hazard."

 Now I would have to call that questionable. I have spun PM motors so fast they locked up, did not know anything about the voltage and don't care, it was not a hazard due to voltage, I just wanted to see if a 3v dc motor would explode at 2,000 rpm. Nope it just fried the bushing/bearing or what ever way before that speed and locked up. Broke my rubber band too

I suppose I was getting maybe 12- 24v tops before it broke?? If even that much?

Not really a hazzard in my opinion