How do they get 60 hertz from windmills ??

**vicegrip** · 04-18-2007, 06:42 AM

I machine huge gear-housings that sit over 200 ft. off the ground . Generating electricity from wind.

the shaft for the prop must be at least 16" in dia. and the generator shaft appears to be 9 or 10" in dia.
We only have blue-prints of the housing but proportionalising it to other housings , that I have milled it looks like in the niehborhood of 1:3 geared up .....in the videos on-line the prop seems like 30 or 40 rpm.

I remember watching the digital tach at the power-plant .....on the turbines ....and I never saw a fluctuaion of more than 2 rpm .....and most often 1 or less.
Even when you could hear the sound of the boiler feed-pumps rise and fall .

How can something as unstable as wind .....drive a generator and give a good 60 cycles ??
I reallise the blade-ing is vari-pitched for wind-speed .....but how responsive could that be??

unless these units provide a power that is collectively put through an inverter ??
or what to get the grid voltage and frequency necessary ??

Phil

**enlpck** · 04-18-2007, 08:04 AM

Some charges batteries using a DC generator or an alternator (like in a car) and either suppliy DC or used a motor-generator set to get AC. More modern setup use inverteres.

There are some that use continuously variable trannies to try to match speed.

Some smaller units use induction machines (AC motors)... These can run asynchronously to the power line. Make power as long as they are turning faster than the synchronous speed. Might turn barely faster at low wind, making little power, to several percent faster in a high wind, making max power. No wind: disconnect. Real high wind: feather the blades to limit speed of windmill.

All will have a gearbox, as the efficient speed for the blade set is slower than most generating gear wants to turn.

I think the most efficient modern units (not my industry... just going by what the trade rags say) use alternators and inverters for high efficiency and load balancing.

**rat4spd** · 04-18-2007, 09:58 AM

The AC output of the variable speed generator, which generates at a speed that is most efficient for the circumstances is rectified into DC, then run through inverters to convert it back to AC at 60 HZ.

**Jim-Tx** · 04-18-2007, 10:26 AM

Phil,
I can't answer how the electricity is converted or whatever happens to it. I only know that it's fed into a power grid of some sort. I just wanted to mention that the area I live in seems to be a hot bed for wind turbines. There are several hundred within 40 miles of here. Some have been in use for several years and a new project is underway to construct several hundred more. If you have never seen one actually working it's a pretty amazing sight.

**vicegrip** · 04-18-2007, 11:00 AM

Originally Posted by Jim-Tx

Phil,
If you have never seen one actually working it's a pretty amazing sight.

I'll bet it is , the two halves once I've bolted them together supposedly weigh over 5000 lbs.
and that's EMPTY ....no shafting !!

I'd be happy just to see them get one put together , let-alone see it run .
I told them I'd go ,if we ever need to send someone to a site .....!!

Phil

**whateg0** · 04-18-2007, 01:29 PM

Here are a couple of pics from last summer about 40ish miles east of here.

Notice the little-bitty man-door at the bottom of the tower.

And these aren't even the big ones! I can't remember the page, but there are pics of some off the coast of Norway (maybe) that are reeeeaaaalllllly big!

Dave

**Jim-Tx** · 04-18-2007, 01:48 PM

Here is a link to the first wind farm in this area. There are more now!

http://www.trentmesa.com/techdetails.htm

**vicegrip** · 04-18-2007, 02:04 PM

Originally Posted by whateg0

Here are a couple of pics from last summer about 40ish miles east of here.

Notice the little-bitty man-door at the bottom of the tower.

And these aren't even the big ones! I can't remember the page, but there are pics of some off the coast of Norway (maybe) that are reeeeaaaalllllly big!

Dave

Originally Posted by Jim-Tx

Here is a link to the first wind farm in this area. There are more now!

http://www.trentmesa.com/techdetails.htm

Cool

thanks guys !

We are looking at doing even bigger ones in our shop ...not sewed up yet ...though

Phil

**vicegrip** · 04-18-2007, 02:22 PM

My wife want's to know ...from you guys in Tornado - Country ......
How do these things hold-up to to a catagory 3 , 4 , 5 ....who counts after that

Phil

As far as "On Topic"
I have to think those blades are hollow , and formed from progresively thinner sheet
as they go from hub to tip!??!

**TEK** · 04-18-2007, 07:32 PM

Originally Posted by vicegrip

I have to think those blades are hollow , and formed from progresively thinner sheet
as they go from hub to tip!??!

I cant tell you anything about how they work but I did get to go up in one once and the props are hollow and I'm thinking were made out of fiberglass. In '94, when I lived near Palms Springs, my neighbor worked for a company that serviced them. He invited me to go with him one weekend. I sure wish I had pics. It was 150' at prop centerline and 165' to the top of the 'house'. We went out on the roof to enjoy the view. It was only blowing about 8-10 mph that day so it wasnt shaking too much.

**btalley63** · 04-18-2007, 07:44 PM

Hey Jim-Tx,
My Dad lives about 3 miles south of the wind generators south of Abilene. In Shep, if you know where that is. They seem to have chased all the deer on to his place. I'm not complaining.

My Aunt pulled off the road to look at one close to the hwy on 277. A maintenance guy walked up and let her and her husband come into the gate and get a little closer look. She said all you could hear is the blade coming close to you making a whoosing sound. The things turn a constant speed wether the wind is blowing 5 or 50 mph. That's a good question about what happens during tornados. Those things are really amazing. Here in Ft. Worth you always see the pieces parts being transported down the interstate.

B.

**notme** · 04-18-2007, 08:12 PM

i was on a job last summer, we put up 126 of those big windmills.....the blades are fibreglass, and 120' long..they pitch into the wind after a certain windspeed to prevent overturning...

**Jim-Tx** · 04-18-2007, 08:47 PM

Originally Posted by btalley63

Hey Jim-Tx,
My Dad lives about 3 miles south of the wind generators south of Abilene. In Shep, if you know where that is. They seem to have chased all the deer on to his place. I'm not complaining.

My Aunt pulled off the road to look at one close to the hwy on 277. A maintenance guy walked up and let her and her husband come into the gate and get a little closer look. She said all you could hear is the blade coming close to you making a whoosing sound. The things turn a constant speed wether the wind is blowing 5 or 50 mph. That's a good question about what happens during tornados. Those things are really amazing. Here in Ft. Worth you always see the pieces parts being transported down the interstate.

B.

Yep, I know where Shep is. Don't get down in that part of the county much, but have been there. We used to have the top of the mountain leased for deer hunting where they put that first wind farm near Trent. The road up there was just about 4x4 necessary. I'd like to go out there now and see what kind of road they built for those big trucks.

I don't know what the max wind would be that wouldn't damage them. I'm sure a direct hit by a tornado would be more than they could take but the odds are pretty slim of one being hit directly.

**whateg0** · 04-18-2007, 08:55 PM

Originally Posted by vicegrip

My wife want's to know ...from you guys in Tornado - Country ......
How do these things hold-up to to a catagory 3 , 4 , 5 ....who counts after that

Phil

As far as "On Topic"
I have to think those blades are hollow , and formed from progresively thinner sheet
as they go from hub to tip!??!

I don't know about tornados. I think they duck down into a ditch. (Don't worry, they stay away from overpasses!)

Really, I don't know. I'll let you know if a tornado goes through any around here.

The blades are hollow, sorta. They seem to be made of some sort of composite that has some flex to it. There appears to be some sort of "spine" perhaps, or maybe it's something to dampen vibrations. They don't really look that tough, but I guess under normal circumstances, they shouldn't be hitting too many things.

Dave