Fisher & Paykel Smart Drive

[Jedon]

What are peoples opinions of these? I'm planning out my microhydro ( 100ft head, 20gpm, pelton ) and units powered by these are cheaper than the PM alternatives.
EcoInnovations in NZ sells a full setup for $1200 shipped + $500  for 48V
https://www.powerspout.com
I could put a system together out of parts, $100 off Ebay for the pelton wheel, $100 for a Smartdrive motor, $10 for water jets, ? for bearings etc, ? for time and effort.
I'll start off doing the weir and penstock anyway so I have some time to really work out the power generation part.
Distance from generator to shed with batteries etc is probably going to be around 600ft. Bank is 48V.

[mobile_bob]

personally if i were going to transfer 600ft, i would want to generate at 240vac or more

of course it depends on how much power are you talking about?  200 watts or 2000watts?

bob g

[sailawayrb]

personally if i were going to transfer 600ft, i would want to generate at 240vac or more

of course it depends on how much power are you talking about?  200 watts or 2000watts?

bob g

With that head and flow rate it would be 200 watts.  Of course, it's 200 watts for 24/7 without dealing with fuel.

[Ronmar]

DC over 600'?

I would be looking for 240 vac or more, for the main reason that the wire to move any appreciable DC current that distance is going to cost a small fortune.  Multiply the voltage by 10 and you only need to carry 1/10 the current for the same ammount of energy delivered.  That is a whole lot smaller wire.  I would be looking for a 240V or a 480V 3 phase generator head and step the voltage down and rectify it at the battery bank...

[BruceM]

The trick will be finding a 250 watt size alternator with a high voltage output, preferably with a PM rotor, as running power for excitation would be a pain.  Since the wattage is so low, single phase would be OK;  it's not a big deal to filter just 5amps of current (48V DC battery bank).  

I think I would look for a  brushless DC motor to convert for this application, but maybe someone else would have some better ideas.  

It's a pity to have to pay for a 1250 watt pelton wheel/generator system when you only are going to get a couple hundred watts.  

PS-  Such a beast does exist, this found at backwoodssolar.com: W-STREAM 2:

2 nozzle with 240v High voltage alternator for long distance transmission can be special ordered: $2670 plus $50.00 shipping; 8+ week lead time  

Plus another $900 (!) for a 400 watt step down transformer.  Ouch.  

These  low volume products sure are pricey!

[mobile_bob]

at those prices, independent R&D becomes very attractive

i would be looking into building my own turbine, using stainless spoons, and rewinding a stator for single phase
and pm excitation (as Bruce suggested).

i am not at all convinced that one could not come close to the same output for a bunch less money, provided one
puts enough time and persistence into it.

even if it only put out 100watts, build two of them!

bob g

[mobile_bob]

this is going to be a case where i would build the turbine first, then test it with a prony brake to determine
it maximum power curve (best rpm vs torque) plot the two and find the intersection

then design an alternator to fit the parameter, bearing in mind that the higher the voltage the more efficient the alternator

transfer the power via high voltage AC, then step it down and rectify it for battery charging at the other end.

the wind power boys fight this battle as you know, and usually end up with about a 50% efficient alternator, which might
be good enough for your needs, however

if you can get 200watts with an alternator that is 50%, getting one that hits 75% will return  300watts,, which over a course
of a day is certainly worth the extra effort if you have need for the extra power.

in this case perhaps one of the aircore designs or the iron core axial could be used to good effect, you can tailor its operation
by altering its airgap, and you can wind the puppy for whatever voltage you want.

bob g

[sailawayrb]

Bob G., you arrived at exactly the same conclusion I did several months ago when considering my hydro power situation.  I decided to design/build myself so I could optimize the hardware to the site.  I will be moving about 650 watts about 150 feet and planning to do it via 240 VAC.  Having 240 VAC directly (and easily get 120 VDC) can come in handy.  I also used this project to justify in my mind a good reason to finally get a lathe and a mill.

[Jedon]

I'll go measure the flow today, I measured 20 gpm right at the end of summer in a drought year so that would be the minimum. Maximum may be 4x that.
Why use spoons over a $100 cast pelton wheel off Ebay? To maximize the speed/torque by changing the diameter? If I know exactly what I want I think I can find someone to cast me a bronze one as an art project.
When considering DIY, I have some time but not a lot so full blown engineering projects are out of the question really. I'm also tight on money so some combination of DIY and off the shelf would be perfect.
I've seen videos of the smartdrive motors being adjusted for power output so if it's designed right that could be taken advantage of.
I like the idea of an axial flux alternator, I was going to order one for my 6/1 but they didn't respond to my request in time.

They do offer this for $499

PowerSpout HE (Upgrade)

This is the High-voltage Enabled version of the PowerSpout.

This is similar to our BE version but at a higher voltage and 3-phase ac output. The turbine will generate 300-500 vac that is fed into a battery bank via a step down transformer pack. A regulator and inverter system is required as per the BE version.

The main advantage of this over the BE PowerSpout is that the cable cost can be significantly less at these high voltages. The battery bank it typically 12/24/48 vdc. Only use a PowerSpout HE if you cannot economically cable your hydro at 100 vdc using our PowerSpout ME version. At 300-500 vac extreme care must be taken, this product is not for the DIY'er, only the professional RE installer.

[BruceM]

I agree, $3500 is in the range where DIY starts to look more fun.

As Jedon says, you can buy aluminum or fiberglass Pelton wheels pretty cheap on Ebay...about $100. that leaves the high voltage 200 watt alternator. The diameter may be too large for a 200 watt system, unless the alternator is efficient at lower rpm.

One thought- since these are continuous and stable in operation, you could use the output AC to provide DC excitation via small toroid transformer and bridge; initial start could be via battery or charged up capacitor.  

The cheapest auto alternator might be a start; rewind the stator for high voltage, maybe replace coil in claw pole assembly Or try some PM's  to replace the coil?  

Lastly, I wonder why there are no low speed, piston type pumps for microhydro?  Efficiency of the Pelton wheels seems likely to be poor in comparison.  

Jedon, I think flow rate is limited by your select pipe diameter, as well as supply.  How did you measure your flow rate?  (I'm not familiar with micro-hydro system design.)

[BruceM]

I just read a couple articles on the F&P motor used for as a generator; it looks like it should be much more efficient at low rpm, and far more suitable than an auto alternator for you application, Jedon.  

I'm looking forward to learning more about the F&P used for your project!

Here's a source for a complete system, high voltage wired F&P alternator (300-500VAC), transformer, etc.

http://www.ecoinnovation.co.nz/p-17-pelton-turbine-high-voltage.aspx

This system price is  $1700.  Even with shipping from NZ, that's a much better deal than the Canadian unit above (Stream).

[Jedon]

Bruce,
The link you posted is EcoInnovations in NZ who as it turns out also makes the Powerspout system I posted initially. For $1700 USD ( Powerspout high voltage AC, their newer product ) shipped it's certainly more affordable than systems from E&S and Harris.
I measured flow the simple way, the stream flows through a culvert so I just put a 5g bucket on the outflow and timed how long it took to fill up. So far depending on the season it's taken anywhere from 4-9s to fill the 5g bucket.
Piping size is certainly a consideration, too small and I have high friction losses and potential loss of flow rate, too large and I can't keep the pipe full which is even worse. I'm thinking 2.5" would be good, although maybe I should do 1/2 in 3" and the rest in 2.5".

[BruceM]

I'm really out to lunch that I missed your original link.  Sorry! 

Very handy that you already have the full flow in a culvert.  That sure simplifies your supply inlet.

Rewiring your own F&P would be an interesting project if you have the time.  Sometimes the money you save isn't worth the time it costs.

[Jedon]

A guy in NZ has some and will re-wire for $10/hr, takes 2-4 hours depending on what configuration you want. HE was selling them for $20-$50 each so even with shipping might be a good deal. The guy in the US selling them for $105 has factory seconds though so they are brand new.
The culvert is handy right now for measuring flow but doesn't help any with the actual project since it's downhill from where the pelton will go.

[BruceM]

You can't beat that price for rewiring!