Typical rotor RPM, also Ametek 30v motor?

[KC8QVO]

I am just about to start welding up my turbine main frame (motor mount, mast bearing, tail bearing) and I need a bit of advice. I really think that my Ametek 30v motor is going to need to spin faster than my rotor will spin in normal (around here - 10-15mph) winds to get up over my battery voltage. I can't spin the hub on the motor with my hands fast enough to even hit 10 volts - I can get it to 9v if I really flip it hard.

I am shooting for 4' blades, so 9' diameter (plus 12" for the hub). What RPM's can I expect to see out of this in low wind speeds?

Also, does anyone really know what RPM I need to hit with the motor to get up over 13-14 volts?

I spun the motor shaft with a lathe but I am not wanting to trust the RPM guage on the lathe because I was up around 1500 if I remember right. I couldn't get it fast enough in low so I wen't to high and still had to crank it. 1500rpm just doesn't sound right to me. Given the condition of the lathe I wouldn't be surprised if it was off a bit

Once I get the numbers right I can build a step up drive to convert the speed from the low RPM of the rotor to high rpm's at the motor.

Steve

[KC8QVO]

I just stuck the motor back on the lathe real quick and here is what I got:

950. rpm = 12 volts
     
1100. rpm = 14 volts
      
      

Do those numbers make any sense?

Steve

[KC8QVO]

Hmm.. that "100 rpm" should read "1100 rpm". Apparently it got re-formatted.

Steve

[Flux]

No chance without gearing with that size prop. Prop ought to hit cut in about 150 to 180 rpm.

The prop is too big to use direct, the bearings or shaft won't stand it. Typically those Amtecs are used with a 4ft diameter prop.

I strongly suspect that with your large prop and a speed increasing transmission you are going to burn the motor out or have the prop run away but you may get it to furl in time.

Flux

[KC8QVO]

Right now I am only planning on using this thing in temporary setups anyway (Field Day towards the end of June specifically). I am more concerned with the low speed performence rather than building it to withstand severe winds.

My thought with the big blades is to get enough torq in low speeds to crank the motor hard enough to get useable electricity out of (high enough voltage to charge batteries).

I would need one heck of a gear increase to make the voltage high enough to use though.. like a 1:10 ratio. This might get interesting!!!!

Steve

[Flux]

Almost certainly the gearing required will defeat your low wind aim. You likely do need that size of prop for reasonable power on normal days. These silly motors remain toys. The common lower speed one would be a far better choice with perhaps 3:1 speed increase.

Flux

[Basil]

Something does not sound right about your numbers. Read this.

http://www.tlgwindpower.com/ametek.htm

[Flux]

I wonder if it is an Amtec 30, there are others with much higher speed for nominal volts. I thought the 30 made 12v at about 400 rpm.

Flux

[windstuffnow]

 12 volts at about 330 rpm for the Ametek 30.  With a 4ft prop running at a TSR of 6 would cut in at or around 7.5 to 8 mph.  For a 3.5 ft prop the cut in would occur at around 6.5 to 7 mph.

.

[KC8QVO]

Here is a link to a picture of my motor. I tried to get the numbers on the label too.

http://i118.photobucket.com/albums/o117/KC8QVO/Wind%20Turbine/IMG_3599.jpg

Steve

[Flux]

Those familiar with these things may be able to tell if that is the common 30v unit. I can't seriously believe your speed measurement is in error by a factor of 3 so I think you had better base it on your measured figures.

Nothing on the name plate to give any clue.

Flux

[ZooT]

Yeah.....it should hit cut-in at about 400 RPM's....

It's kinda sad though that there's an awful lotta' mismarked motors floating around out there.......

I've bought three "30 volt ametek" motors.....and they're all different......and I wonder what model number of avery sticky labels is the right size for ametek counterfieting....as some of the ametek motors just aren't worth squat for wind turbines.......and probably a lot are remarked because the 30 volt is actually a pretty decent little generator....or at least one of my three is....

Heck......I can hit 12 volts on that one spinning it with my fingers....

[FishbonzWV]

Pull the brushes out and blow compressed air into the commutator, then reseat the brushes.

When you get it flying, if you see a drop in output, reclean the brushes.

[Norm]

I may be wrong but an actual Ametek 30v motor

 will be specifically and physically different

than any other ....that is it will be so long,

a certain size diameter the shaft will be a certain size,

even the length and weight.

http://www.tlgwindpower.com/ametek.htm

You'll notice in the data there is a very subtle

difference between the 30v and the 36or37v !

 As a side note it looks like he has some really

excellent blades I'm not connected to his products in

 any way....just my own personal opinion.

[KC8QVO]

I blew everything off inside the motor and no change. It must just be the way this unit is. I am going to use two-step belt drive to ramp up the RPM's 1:10. It won't be an efficient drive but that is the way it goes. This whole turbine isn't going to be an efficient system as it is.

Steve