Author Topic: I found this at "work" the other day...it failed to handle the load...  (Read 742 times)

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TheEquineFencer

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The center of it kind of got ripped out when the 1200Ah low/discharged 24V battery bank was applied to the DC output of the Alternator. The 3Ph's are dumped into a bridge rectifier then into the batteries. Max DC output from the alternator is around 36VDC at 2000 RPM with a 210A output. Right now the "bandaid" they put on it is to install a 60A MorningStar Tristar MPPT to limit the voltage/current to a max of 60A to the batteries.

When I saw the alternator end after I took it apart I thought about this website. I'm going to see if I can get the parts when they are ready to throw them away. there's like 20 magnets on each of the rotors. The stator (center shaft) stays still and the rotor with the mags rotate as they are bolted to the flywheel.

Some company out of Australia builds the generators for the mining industry.
 

electrondady1

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #1 on: October 17, 2017, 06:54:24 AM »
nice find . you can tell it wants to be a windmill.

TheEquineFencer

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #2 on: October 17, 2017, 07:17:42 AM »
That's what I was thinking. I may end up with 2-3 of them, all failed with the center ripped out from the looks of it. The magnets are thin, maybe 1/8  inch or a little thicker.

My guess is the thing heated up because it couldn't dissipate the heat fast enough and the stator came in contact with the rotors and ripped the center loose.

I'm wondering if I get it, build a new center plate with the windings in it with larger wire for lower RPM and space the plates a little more apart for some cooling.

SparWeb

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #3 on: October 17, 2017, 12:26:46 PM »
Cool
Sealed oil bath, right?
It looks to me that a magnet is dislodged.  First picture, left-hand half, 11 o'clock position.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

joestue

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #4 on: October 17, 2017, 12:43:24 PM »
That's what I was thinking. I may end up with 2-3 of them, all failed with the center ripped out from the looks of it. The magnets are thin, maybe 1/8  inch or a little thicker.

My guess is the thing heated up because it couldn't dissipate the heat fast enough and the stator came in contact with the rotors and ripped the center loose.

I'm wondering if I get it, build a new center plate with the windings in it with larger wire for lower RPM and space the plates a little more apart for some cooling.

you've got an ideal candidate for rebuilding there.

the shape of the existing coil is probably somewhat ideal. i would not re-wind new coils if you can use the existing coils.

as far as:

Quote
larger wire for lower RPM and space the plates a little more apart for some cooling.

no, not at all. to get more volts out you need more turns of thinner wire.

spacing the magnet plates further apart will do nothing for cooling because the churning of the air between the rotor and the plate is what pushes heat through the air gap. radiation won't be changed by the gap either. you would want it as little as possible.

and the magnet flux will be decreased by the larger air gap, and the magnet flux squared is what sets the performance of an electrical motor.


at direct drive wind turbine speeds.. liquid cooling would be great.

TheEquineFencer

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #5 on: October 17, 2017, 01:22:10 PM »
No, they were not liquid cooled. Yes one mag did come loose, unglued, but was not broken.

SparWeb

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #6 on: October 17, 2017, 06:42:44 PM »
I agree it would be a great candidate for rebuilding.  Depending on how much of the stator can be salvaged, I'd consider that making a new stator from scratch would involve some compromises and you may end up needing to space it apart some just because you chose, maybe, to rewind with thicker wire, or more turns, or whatever.  Once you commit to the rebuild and choose the purpose for the machine, you will probably want the re-wind to match the end use.  You've got a great machine there, and an opportunity to tailor it nicely for your desires.

Even if it ends up derated from 7kW to 5kW it is an excellent starting point.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

eigenmorph

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Re: I found this at "work" the other day...it failed to handle the load...
« Reply #7 on: October 18, 2017, 08:27:30 AM »
A lucky find right enough. If I am recall correctly, Northern Power use permanent magnets for their wind turbines. The generator is connected directly to the turbine, dispensing with the cost and losses of a gearbox. This means the rotor will rotate at about 20rpm or less. That in turn means that the internal arrangement must be more than 100 pole if it is to produce AC at 50 or 60 Hz directly. If the output is rectified and then applied to an inverter, then the number of poles doesn't matter. I played around with an old motorcycle alternator in this way back in the late 1980s, but I never took it very far.

If I understand correctly, the alternator you have was rated for use at 2000 rpm. From the rated output, you can work out the torque that the magnets produce. As a rough guide, If you reduce the rpm, the maximum power output is reduced in proportion. Iron and Copper losses are not linear, and how you rewind the stator will determine the actual power you will be able to produce.

Have fun with it whatever you do.
All the best. Jim. heronmeadows.com