5kw Poncelet Wheel Project

[DanG]

They've got something umnn think opposed freehubs on that top jackshaft - sleeved rods bind to chain to impart the up/down, the opposed geared cogs take up/down into drive motion - all very low speed, the chains/belts/hubs/gears would need replacing before the shaft-clutched gears...

[MattM]

joestue, you make a solid point.  The raw drive force from the water should make gearing losses a minor issue.  A much smaller PMG would be necessary with gearing.  Cheap magnets would benefit from the larger PMG diameter since you raise tangential velocity and cooling surface as the wheel diameter increases.  But you also seem to raise copper wire use at the same time.

That giant rotor made from steel looks expensive, too.  I'm thinking they could have built something out of marine grade plywood and had identical results for a fraction of the cost.

[skid]

I ordered a new generator. I'm too busy with other work to even consider making my own right now. The new generator should be here in a month or so. I sized it down some since the wheel seems to be limited to 2kw in its current configuration. I will build a cover for it to keep water away as that was the reason for the failure on the original generator.

At some point in the future I will modify the blade design as I know for sure the blades are too short and are not using the water very efficiently. I can double the blade area by adding a foot of blade length and widening the blades by 10 inches. This will still fit within the existing frame with no modifications.

I still need to deal with belt slippage under high loads  from wet belts. I should have gone with a chain set up. A timing belt won't work as they are not made long enough for my application. Perhaps a fully guarded belt drive will keep the water off...

[frackers]

Do you have a pinch idler on the belt(s) or is it just tensioned to reduce slip?
I had the same problem on my walnut washer machine going from a 6" pulley to a 30" drum and by pinching the belt between the two pulleys it increased the contact circumference on both and eliminated the slip.

[skid]

Do you have a pinch idler on the belt(s) or is it just tensioned to reduce slip?
I had the same problem on my walnut washer machine going from a 6" pulley to a 30" drum and by pinching the belt between the two pulleys it increased the contact circumference on both and eliminated the slip.

I could add a tensioning idler near the small generator pulley. Unfortunately when I sized the belts I ordered them as short as possible to allow for belt stretch and tensioning. I can probably pick up additional circumferencial (is that a word?) contact with an idler, but not a whole lot.
I'm also thinking of adding a short shaft between the belt pulley and the generator so I can really tighten the belts  without wearing out the generator bearings. I was thinking of using my old water wheel roller bearings for this since they are designed for huge loads.
To do this I would have to move the generator inboard and extend the mounting plate, but that wouldn't be too big of a deal.
I have to get a new taper lock anyways since the new generator shaft is smaller than the old one.

[ontfarmer]

Add a second shaft in a elevated position that has a greatly increased pulley diameter,  so you can use your  existing drive pulley and belts.  Use large diameter pulleys sized to give you the correct ratio for your generator on the second stage.  This will greatly increase belt velocity and contact surface of the belts.  You can use the existing generator mounting. Belt tension could be done from the second shaft.

[MattM]

So is your wheel out of the water until you get that new motor, or are you still using the old one?

[mbouwer]

Skid,

Is it possible to skew the blades of your waterwheel?
 You'll get a much higher TSR then
 a higher rpm of your wheel
 a smaller gear ratio
 higher returns

Regards Rinus

[skid]

So is your wheel out of the water until you get that new motor, or are you still using the old one?

Yep, sitting idle right now. New generator is on its way, Good thing the freshet hasn't started yet.

Skid,

Is it possible to skew the blades of your waterwheel?
 You'll get a much higher TSR then
 a higher rpm of your wheel
 a smaller gear ratio
 higher returns

Regards Rinus

I've had some outside interest in my design. If anything materializes I may do some further experimentation with blade design. For sure I will make it wider to capture more energy.

[MattM]

If it is wider you're going to have much higher side loading, right?  Going to have to beef up the bearings even more.

[skid]

Bearing loading has never been an issue. It was either water getting into the roller bearings, or not enough water lubricating the wood bearings.

I've drilled a hole into the wood bearing so when the wheel is in operation, water will drip into the top center of the bearing providing lubrication.

Depending on whether the bearing wear is unacceptably fast, I may still put a funnel on it as well to capture more dripping water. I drilled the hole to 3/4 pipe thread size so still need to thread the hole and add a pipe and a funnel to the pipe.

[oneirondreamer]

Hello skid,

I'm wondering how your projects progressed?    I'm doing something related, however much smaller, and with a very different turbine.    If my testing works out, and you are still on pause with yours, perhaps we should talk?


https://www.instructables.com/id/Micro-Kinetic-Hydro-Power-System/

Best
Drew

[skid]

Well, new year, new problem

We had a lot of rain and my waterwheel was cranking out some good power when I checked it at night. When I went out in the morning to look, the wheel had stopped turning despite high river flows. I did some trouble shooting and traced the problem to the Wind interface box which is basically a rectifier which converts wild 3 phase into DC

My ABB or Powerone wind interface box is grounding out internally. I'm not sure what the problem is. Anyone have any ideas on what to check?

[SparWeb]

I once had a rectifier fail to short.  Thankfully there are 2 diodes in the rectifier's path between AC and the battery, or my batteries would have discharged though the stator of the wind turbine until they were dead.

Looking in your box, I have to make some guesses:
Bottom Left: Black+Blue+Red is 3-phase AC from the generator
Bottom Right: Black+Blue is DC to your batteries.
Left Side: Anodized aluminum heat-sink.  3-phase rectifier with screw terminals.  Other stuff needing heatsink.
Right Side: Capacitors to suppress noise.
Center: Fuses and other small components (possible current transformer or shunt?)

If any of those assumptions are wrong or need refinement, please let me know.

"What" is "grounded"?  If you disconnected the ground, would that thing still be grounded?  This kind of fault often blows fuses, so check all the fuses in there.

Another simple place to start is to disconnect the 3 wires from the generator, and test continuity through the phases of the generator.  Resistance should be equal on all phases.
While disconnected, check diode voltage drop across the rectifiers.  Many multimeters have a special setting for diodes that will tell you directly if it blocks current when reverse biased.
Other obvious things: Voltage from the batteries is present where it should be - and not present where it shouldn't be.
Examine wire jackets for burns or melts...

[skid]

Thanks for the reply Spar Web!

Your guesses are correct (I think), except the DC Output goes to the grid tie inverter not batteries.

I checked the fuses and they are good. Wires all look good.

With the Wind interface connected the PM generator will not turn. With it disconnected the generator turns normally. This means there is a short to ground inside the wind interface (I think).

How would I check the rectifier for shorting?

[Mary B]

Top left side... looks like a bridge rectifier, looks like it got very hot with the heat sink grease migrating and what is that black blob on it?

[SparWeb]

I think you should start with the rectifier, too.  In the last paragraph of my last message, that's the basics.  If you don't have that kind of multimeter, then here's something else to try:

Put together a 12V power supply or a battery and a light bulb.  Wire them up so that you can attach the wires in circuit with your rectifier.  In one polarity, the rectifier circuit shouldn't matter and the light will work. In reverse polarity, the diode should stop the light from turning on.  Test the rectifier from positive pole to each of the 3 phase terminals, and it should also work, reversed, from the 3 phase terminals to the negative pole.  For each combination, try it normal polarity to confirm the light turns on, and reverse polarity to confirm the light doesn't come on.

Based on your previous posts I get the impression that you'll get my drift from just the words.  If it's still not clear, don't feel like a noob, just ask.
No matter what, it will go easier if you dig up the schematic of the rectifier block from the datasheet.
www.datasheetcatalog.com

[MagnetJuice]

I looked for a schematic with no luck. I think that ABB doesn't want customers fixing those themselves. They want to sell new ones. Shame on them.

I found this:



I also found this old thread. Maybe Rob Beckers could help.

https://www.fieldlines.com/index.php?topic=142986.0

Ed

[skid]

Thanks Sparweb and Mary B!

I'll give your suggestion a try.

Also,
I've attached a Windbox schematic that Rob Beckers from Solacity created years ago and was kind enough provide to me. Rob is suggesting the MOV's (The MOVs are the parts named RV1-RV3 in the diagram) may be the problem as he has seen those fail before.

[skid]

Hey Magnetjuice, you posted as I was composing my post so I missed your comment.  I've already contacted Rob as he has helped me out before and is very knowledgeable on these (as well as being a very nice and helpful guy:). He sent me the schematic I attached above. I'll do more troubleshooting over the next couple days to see what I can find.
Thanks

[SparWeb]

I'm pretty sure the bridge in the schematic above looks like this inside:



Trouble-shooting that is what I was describing before.

Now that I see the rest...

There's a brake switch in there.  Your problem sounds like a brake that's "on".

[Rob Beckers]

Thanks Sparweb and Mary B!

I'll give your suggestion a try.

Also,
I've attached a Windbox schematic that Rob Beckers from Solacity created years ago and was kind enough provide to me. Rob is suggesting the MOV's (The MOVs are the parts named RV1-RV3 in the diagram) may be the problem as he has seen those fail before.

Actually my first suggestion was the bridge rectifier. I've seen those go more than a few times. They are undersized to begin with (in terms of current rating), and the heatsink is much too small in case it runs at large currents for any amount of time.

The second item I've seen fail are the MOVs, and when they fail they generally fail as a short.

By the way, the crowbar circuit in there is designed wrong from the start. It's supposed to blow the fuses in case of over-Voltage, but it never does. Instead it blows the NTCs or does other damage (in effect destroying the wind box instead of protecting it). Not Power-One/ABB's finest work...

-RoB-

[MattM]

Could the rising water level have affected his grounding?

[skid]

Did more checking on the windbox today. I disconnected the (+) and (-) leads off the rectifier and the generator spun normally. If I connect them the generator won't turn. I measured resistance on the rectifier and got an open circuit, but on the +/- leads I got 6.7ohms.

Does this mean that the problem is on the DC side of the rectifier? Should the positive and negative leads read  open circuit?

[skid]

Just thinking out loud here, I wonder if I could put the +/- wires to my inverter directly onto the rectifier and bypass all the windbox DC circuitry?

[Rob Beckers]

Skid, does your inverter use a frequency vs. output power MPPT curve? Or just the regular Voltage vs. Power curve? If the latter, you can just buy a decent sized 3-phase rectifier (I think I've already E-mailed you a link with one that would work), bolt it to a heatsink, and use that. You don't need a windbox, a regular 3-phase bridge rectifier will work fine.

-RoB-

[skid]

Hi Rob,
I've ordered a 100A rectifier with a heat sink, which should be here by the end of the month.

I'm not sure how my inverter is set up. I gave the supplier a power (KW)/ RPM graph of the generator's output and they set up the inverter based upon that.

[Rob Beckers]

I was asking because the windbox generates a frequency signal that can be used for an MPPT curve that uses frequency vs. power. Of course, just a bridge rectifier won't give you that frequency signal, and if that's what your inverter is set up to use it won't work.

Generally, if the two "wind speed" wires are NOT connected from the windbox to the inverter then the inverter has to be using Voltage vs. power and you're OK. If those two wires are connected it could be using either mode.

-RoB-

[skid]

The wind speed wires are not connected so I should be good to go with the new rectifier when it arrives.

[skid]

Well, I hooked some temporary leads from the DC side of my windbox rectifier directly to the leads to the inverter, totally bypassing the DC side of the wind box. Success! Back to generating power!

So, the problem is in the DC side of the wind box. I'm not sure what it is but I'll try to figure it out someday.

For now I'll do a more semi permanent wiring job instead of the alligator clips I'm currently using and wait for a new heavy duty rectifier which I'll permanently wire in.

Thanks to all who helped with this and especially Rob for his in-depth knowledge of these! Good to know I can run on rectifier only!

[skid]

It's been a couple years since I last posted, but the waterwheel has continued to operate with no issues besides belt slippage limiting power output.

Earlier this year I spec'ed and purchased a chain drive that I'll install, and will lengthen/widen the blades to take advantage of this no slip drive system. The good news is thata chain drive won't require heavy loads on the bearings by keeping the belts as tight as possible. The bad news is that I recently found that Gates is now making a polychain drive system in lengths long enough for my application.

For a chain drive I need a cover/guard to protect the chain from water, and need a means to lubricate the chain (likely an oil sump). The polychain is a toothed belt system that needs no protection from water and is designed for low rpm torque transfer which describes my situation to a tee.. Too bad!

One advantage of a chain however is the compactness of the sprockets, especially the drive sprocket on the wheel. I've noticed that the deeper I submerge the wheel the more power it makes. I'll be able to lower the wheel into the water at least another foot, which will add significant output. So maybe the chain won't be so bad after all. I just have to keep water away and the links lubricated.

I'll put the chain on early next spring and widen/lengthen the blades before the spring melt. For now I can get everything ready and fab up a chain guard system.

My Nephew did a drone video of the installation if interested - https://www.youtube.com/watch?v=_adG4e1BCiw&t=47s - No new exciting projects for 2022 though as per the video. Thought I could get the chain drive installed and widen the blades, but had some other things come up that took up my time.

[SparWeb]

I got caught up on some of your videos.  The fallen/floating trees must have put your wheel in danger!  I didn't see much harm however, so it's one more way your system looks robust.

When does the water start running in the spring?

I haven't gone back to check, but didn't the subject of chains come up before?  What changed that convinced you that a chain can be protected from the elements now?  IIRC you had your doubts about corrosion and seals breaking down, when you started.  It's been 5 years so if my memory is faulty just say so!

[skid]

The trees bent a few blades but really didn't affect operation. I pulled it out of the water today since it was starting to ice up. It's on shore now so I may fit the sprockets and put the new roller bearings on if the weather allows. The wood bearings are still serviceable but starting to wear pretty good. I may press in some UHMW and keep them as a back up.
Regarding new bearings and chain drive, I'll be sure to protect everything from water as best I can. Everything will have a cover that directs water away. I may even get a few sheets of 1/4" aluminum plate and extend/widen the blades. Now that the belts won't slip I can make some additional power.