What to look for when searching for a PM motor?

[unclebuckmjmp]

Hi, I've been to this site over the past year and I find it great to read. I'm new to this and I'd like to find out what to look for when searching for a PM motor? I have very little electrical background and looking for something simple to generate power at our hunt camp. Either wind or water will do. We have a small river by the camp and the rapid has a 15 foot drop on a 200 foot run. I have one of those treadmill motors also a Leeson 90V DC. Should I look for motors with lower voltage and RPMs. I've been on EBay looking for PM motors and seen a lot of different ones like DC servo motors and some AC. Any suggestion and Ideas would help me find something and what I can do with it. Thanks

[wooferhound]

This is our most Frequently Asked Question and should be the first writeup in the FAQs area
OH Wait, we don't have a FAQs area . . .

anyway here is your answer...
http://fieldlines.com/board/index.php/topic,136831.0.html
http://fieldlines.com/board/index.php/topic,143212.0.html
http://fieldlines.com/board/index.php/topic,139280.0.html
http://fieldlines.com/board/index.php/topic,132920.0.html
http://fieldlines.com/board/index.php/topic,140464.0.html
http://fieldlines.com/board/index.php/topic,132674.0.html
http://fieldlines.com/board/index.php/topic,133133.0.html
http://fieldlines.com/board/index.php/topic,132245.0.html

[Rover]

Hi, I've been to this site over the past year and I find it great to read. I'm new to this and I'd like to find out what to look for when searching for a PM motor? I have very little electrical background and looking for something simple to generate power at our hunt camp. Either wind or water will do. We have a small river by the camp and the rapid has a 15 foot drop on a 200 foot run. I have one of those treadmill motors also a Leeson 90V DC. Should I look for motors with lower voltage and RPMs. I've been on EBay looking for PM motors and seen a lot of different ones like DC servo motors and some AC. Any suggestion and Ideas would help me find something and what I can do with it. Thanks

Might want to give a little more info. "something simple to generate power at out hunt camp" can mean a lot of different things for different people ... from powering a light in a tent, to having a permanent frostfree refrigerator in a cabin structure.

Do you need AC to power normal consumer equipment?, 12 or 24 volt equipment? .

Basically start with your current electrical needs, then back pedal to what you can live with , and tell us.

I'll make the assumption this is all of grid, so make battery plans as well...you'll need somewhere to store the power, also come up with a frequency of use (and also maintenance...you can store a lot of power in a year for a yearly hunt, but if you don't maintain it... well, you won't have it when you need it)

[hydrosun]

What you are looking for is to match the speed of the water to the speed of the turbine at the voltage you want. You want the turbine to turn at 1/2 the speed of the water hitting it.  A 1800 rpm motor at 120 volts turns at about 200 rpm to charge a 12 volt battery. The rpm of the turbine is dependent on the effective diameter of where the water hits it. The closer to the center the faster it goes. A propeller type turns the fastest, followed by a turgo and then small pelton.   The only home brew style that I'd reconmend for you site would be a turgo. It can handle more water than the pelton. I don't know exactly what it's effective diameter is compared to a pelton but know  the water hits closer to the shaft compare to a similar sized pelton. Maybe someone else on this forum knows the exact number.
Your 15 feet of head tells me how fast the water is moving. I'd need to know the size and type of the turbine to tell the rpm of the motor needed.  Actually 15 feet is below any chart I have so I'd have to interpolate to get close.  I'd look at the ESD low head hydro to get some ideas of an efficient off the shelf solution. That would be running over 1000 gpm and 1000 watts at your site. For less power I'd look at the ESD turgo for maybe 100gpm and 100 watts.  The nice thing about those products is the wiring  can be reconfigured to fit different heads and voltages.
  Fudging the lower head and smaller diameter from the chart I have the ESD turgo at your head would be turning about 900 rpm. so that size turgo would need a motor rated at 24 volts and 1800 rpm to fit close to the speed needed.
Chris

[unclebuckmjmp]

Sorry guys that I haven't been able to get back to you. I just finished working a one week stretch. Getting back to my com suption needs this is a remote camp with no grid available. I have two 12 Volts deep cycle batteries I can bring up. The camp is just under a 100 wards away from the river. We currently run a 650 watt generator to power about four lights, a small TV or the lap top and to charge FRS radios. In PM motors I have presently an old 12 volt trolling motor, an old 3500lbs 12 volt wench motor and 12 volt motor used to turn a water pump on an engine. I also have that Leeson 90Volt treadmill motor. I just wanted to get some opinions to make a decision on which motor I have would do the best job.

I was thinking originally at a paddle wheel at the top of the rapid because of the large flat rocks. They would give an area to set up and the water seemed to be moving quite fast between them. The question on staying AC or DC was because the camp was 300 feet away and should I rectify the AC at the camp or run DC up to it?

I'll try to post a few picture of the rapid so it can give some ideal[/img].

[ghurd]

In PM motors I have presently an old 12 volt trolling motor, an old 3500lbs 12 volt wench motor and 12 volt motor used to turn a water pump on an engine.
I also have that Leeson 90Volt treadmill motor.

Pretty sure the only thing worth even a bench test is the Leeson.
G-

[XeonPony]

300' ?, Well you'd best run A/C and then rectify it at the camp, use 10AWG and you may want to use a 230v motor and a step down transformer.

Or if generating in DC you need to run a pipe close to your camp as you can get, then run a draft channel or pipe back to the creek, if you use a larger pipe for your draft then you are using for the penstock you can gain negative suction head which can help you gain more power for a given drop.

The trolling motor will be more in line with the RPM to power range we want, it all so opens up some intriguing options.

To use the trolling motor and have efficient power distribution you'd need to build the whole generator/charging/battery bank/dump load all at the edge of the river then hook the inverter to the batteries and send the power to the camp as A/C.

Play with the trolling motor and the tread mill motor, use a drill set to its lowest speed and that will give you a good idea of the torque and the volts it will generate at that speed!

A 3500RPM 102V 15A tread mill motor I had would generate 20V @ 1600RPM and out put about 2A apx be for stalling the drill to give you an idea (Note: The drill used for the test was pitiful at best!)

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[hydrosun]

Since you don't appear to need much power, I'd just hook a turgo to the leeson motor  hook it to a 12 volt battery and let it rip. It wouldn't be close to maximum efficiency but over 24 hours it should be enough. if it's not then you would have to find a better matching motor.  I'd avoid the paddle wheel as it would be more maintenance for  part time use. A turgo and motor could be just picked up and taken with you each time. Things left out without the heat of use will just corrode.  I agree it makes sense to have the batteries and inverter by the stream and transmit 120 volts AC to the camp. Make sure you have a way to either shut off the hydro input or a dump load to keep from overcharging the batteries. 
 If the lights are cfl then you load might be only 2 amps at max (depending on how fast the charger is) so you could use 12 gauge wire with low loss.
With small loads mostly at night the total power needed is low. So you can keep it pretty simple. It's not how I ordinarily design a system.
chris

[Ungrounded Lightning Rod]

15 feet of head is kinda low for a pelton or turgo.  They are high pressure low flow devices and are usually used for heads of at least 50 feet.

You might consider a banki-mitchell crossflow turbine - basically a blower-style squirrelcage with the water passing through it crosswise.  (In fact at least one of the board's denizens has made one by mounting an old furnace blower in a spillway.  B-) )  15 feet is right in their sweet spot for head and you can make 'em wide to take more water for more power.  They are self-cleaning because the water goes in one side and out the other, while debris that are too big to go between the rotor blades get carried halfway around and washed back off where the water comes back out.

You're also in the sweet spot for a kaplan and in the low range for a francis.  But those are propeller types and considerably harder to fabricate.

Here's an application chart:

http://en.wikipedia.org/wiki/File:Water_Turbine_Chart.png

and an article on turbine types with links to more detail:

http://en.wikipedia.org/wiki/Water_turbine

[jlt]

What is the depth & speed of the water. You could try to use electric trolling motors .maybe hooking up three or four in series to get enough volts.

[tecker]

Brush motors that cost more than $40 are  a loosing proposition . Also you'll have to compensate for a 250 feet,That's for the most part a losing proposition
several low priced tread mill motors will deal with the 200 foot run . One every 75 feet in series with one close in . yo can replace them with your own builds as they wear out .I like a small dc turbine and a small solar panel in series