The Benefits of Three Phase AC Pumps For Solar Water Pumping

Hedges

I See Electromagnetic Fields!
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Mar 28, 2020
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10,668
I wish ! 423 feet max.

Perhaps there are other designs elsewhere. I heard about these before, finally found a product listing.
These pumps appear to just have a gear drive and vertical shaft, no counter balance. Maybe one could be added?
As shown, appears the motor has to lift dead weight of shaft and water column, which requires torque way above what the average flow/lift would.

Another style looks like an oil derrick, so cable converts motion to vertical and counter weights can be added. Maybe there is a source somewhere.

With smallest cylinder and 2 HP, this says 473' lift 117 gallon per hour. That's 900 gallons in an 8-hour day, but a household without irrigation could get by with much less. Being fixed displacement, if counterbalanced a smaller motor geared slower should work, or greater depth (within pressure limits of pump seals.)

Ideally, pump would run at variable speed depending on available solar power. With fixed displacement rather than turbine pump that should be possible.
 

Pyrofx

Flux capacitor builder
Joined
Jul 27, 2020
Messages
535
Location
Oatman Az
Yes, 10000TLUS said "IGBT error", not sure what state it had been in.
5000US, when it checked line voltage before reconnecting, said something like relay error. Turning off VFD didn't fix, but power cycling PV input did. I think it fed OK with VFD on, but had the problem connecting.

Maybe yet another inductor on input of VFD would help? Slight improvement in PF and waveform but not ideal.

What we want is a front-end that follows AC voltage sine wave and synthesizes sine wave current to charge the capacitors. That does exist, but don't know of an add-on unit.
Well.....
Here's an update.
I used https://ebay.us/cHQj6Y
Short answer , so far so good. Long answer below.

This is all being set up and tested in my shop before taking it out into the desert.

Solar setup:
2 x Sma si 6048 for 220 split ph
1 Sma Sb 7.7
1 Sma tu6000us
2 16s 280ah lifepo4 batts parallel to 1.25x.375 buss bar.
Batt to bus 2/0 copper welding wire
Buss to Si6048 3/0
Rec bms 1 master 6 slaves
1 array trina 250w 12 in series
1 array trina 250w 6 in series


Now I want to test this all out and see if I can run the 3hp well pump. Pump will be at 1030 feet. Bottom 100 feet is number 4 copper well wire. That's 40 submerged and 60 feet above the water level. The balance is 900 feet of number 2 aluminum direct burial wet environment wire.

For a test so far.......
Hooked up the vfd to the Power produce by the inverters. Set ramp for 50 to 60hz over 4 sec. Fired it up , all good no issues.
Ran 50 foot of #10 extension cord up to machine shop and wired it into the 3ph supply. Turned of vfd and then tried a massive 5hp surface grinder. Nope to much surge. It has a mag starter so it's not used in the rest of testing.

Reset vfd. Turned on 3hp turret lathe , the initiated vfd. Ramps up perfect. No faults on inverters.

Turned everything off. Though , go for broke. Turned on 3hp lathe , 1.1hp mini mill , and last but not least , the 2hp Bridgeport mill.
Hit the vfd and crossed my fingers . All ramped up , no faults , and only had amp clamp on one leg. 48amps max inrush.

So far so good. I used the 50 foot cord forb2 reasoned. I had it , and thinking with a bunch of line loss , maybe it would stall.

Next test will be same setup , except through the 100 feet of copper and 1000 feet of aluminum.

If will be a few days to do it , but I have Hope's. Then we will see if I need the reactor.
Greg
 
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Hedges

I See Electromagnetic Fields!
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Mar 28, 2020
Messages
10,668
I think reactor may also be recommended when long run to motor, reduce voltage spikes from high frequency edges?

With a VFD running, if an inverter that has been disconnected tries to connect, that's one situation where mine got upset.
Grid failure was one where Sunny Boy disconnected and Sunny Island picked up the load. When Sunny Boy came back it had a problem.
Ungraceful shutdown of generator might do the same thing. If scheduled by Sunny Island, does it pick up the load then lift relay, then cool-down generator?
Sunrise with VFD running would be a likely one for Sunny Boy to wake up. Hopefully you don't run 1000' deep well pump without sunshine.
 

Guido1

New Member
Joined
May 16, 2021
Messages
16
Lots of potentially complex considerations. Hard to answer without looking at exact equipment specs. Can you post links to data sheets for the Franklin items? Save us the trouble of looking them up.

My first initial thought is that you will probably pay significantly more for unique items, such as a dedicated solar VFD, or unique “solar “ pump. It is probably significantly more cost effective to use a common 3-phase pump motor, driven by a common VFD. But efficiency will probably be a bit better with a DC driven VFD, because of one less conversion loss in the circuit.

At first consideration, I don’t think it would be at all foolish to pass on the special high-cost Franklin VFD box …. Calculate what lower conversion losses you would realize, and compare that saving to the added capital cost

All is complicated by the unique considerations of your install, such as the length and convenience of wire runs, and proximity of panels and inverter to where you plan to install the VFD.

What is this about a 3 HP motor not “requiring a surge” for starting? Can you post a link? Is that a feature of the motor, or the drive? As noted above, no 3-phase motor driven by a VFD needs a starting surge if the motor speed is ramped up over some seconds - easily set within the drive parameters.

4kW of panels can all potentially feed the single 100 amp charge controllers. Depends on VOC of the panels, how they are wired in series/parallel, and the charge controller specs. Again, can you post a link to the charge controller data sheet?
Hello, Johncfii

Sorry for the delay in responding to your inquiry. Spent most of the prior week and all the last weekend having our Houston house shown and sold.
Didn't realize there were so many details involved, I thought you just showed-up at the ex-wife's attorney's office and signed it over to her.

The Franklin VFD controller included with their "sub-Solar" package has a $1398.00 price tag, a different paradigm from the Hitachi and other VFD's shown on your linked page to Wolf Automation. It may be a nice item, but I bet I could make do with a Hitachi or comparable controller.
Heck, I could buy a backup VFD and still be in the black.

The inverter/charge controller is shown here:
It has an 120 amp solar charger, (my poor recollection) and a 100 amp AC connection. Generator input? It weighs 210 lbs. w/ two massive transformers, is rated for 36Kv surge for 5 seconds.
When I mentioned "lack of surge" for the pump driver, I was meaning to say, "lack of surge with the VFD drive", but zero proofreading caught up with me on that one.
I believe the direction I'm going to try and go is another Franklin driver, this one 1-1/2 hp as my current one, but in a 3 phase configuration combined with a VFD controller, probably Hitachi. Mate that up to a new Franklin pump, I reckon the current 3 wire down-hole setup should be re-usable as long as it passes inspection.
The reason I'm going to replace in-kind is to keep my pump guy happy, I suspect he'll be unhappy if I spec out a Grundfos. Besides, this Franklin rig has been rockin' for over 15 trouble-free years.
One burning question: If I segregate my PV's and batteries into 4 different 12 volt groups, do I use a combiner box or boxes to re-join them into a 48 volt configuration? I assume that would be downstream of the batteries, but obviously upstream of the inverter's pair of 48 volt input lugs.
Should I have used 48 volt components instead?

As always, much respect for you wizards willing to assist we the unwashed masses....

The best,
-Guido
 
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ko6kL

New Member
Joined
Oct 13, 2021
Messages
18
The first photo below is the output waveform from my Outback VFX3624 inverters when not powering a VFD.

The second photo is the waveform of input power being supplied to the VFD from the Outback inverters. While the audio frequency ringing imposed on the waveform has never caused any problems that I have detected, I’ve ordered a suitable reactor that might block the ringing from being fed back into my inverter and distribution system.
maybe try a AC line noise filter on that right at the ac input to the vfd.
the caps in the filter will send the high frequency noise to ground and the inductors will help filter it out while the clean 60hz will pass.
On factory equipment I have seen any trash in the incoming AC damage unprotected FVD's... I replaced a few at one factory until someone spotted a wall breaker that was arcing... after that no more dead vfd controllers ( brand was REO ) .
here is the pic of the breaker.
Old-Sparky-Breaker-gif-turlock-ca-- (1).gif
 

Pemba

New Member
Joined
May 3, 2021
Messages
3
I sell "non solar" pumps in the north of Mozambique. All pumps have to be imported here. Obviously there are many types with different Q (discharge) - H (pressure) characteristics. I am interested in getting in to selling "solar pumps" as well. I thought one way to get around the stock issue is using a "solar inverter" which sounds a lot like the VFD's mentioned here - it just also has a DC input in addition to working as a VFD. A "(MPPT) solar inverter" can be used with an ordinary AC pump within range (kW/HP) and "type": 230 or 380 VAC, referred to here as single or three phase. They can be cheap (less that USD 100 for up 1.5 kW). But they require high DC voltage input, ideally 360VDC I think. Enter the "DC Voltage booster". It all seems to work fine, but compared to a straight forward "solar pump" (many of which also convert DC to three phase AC) the setup seems less efficient (less water for the same amount of PV panels). Does that sound right ? So far I've only tried small (up to 1 HP), 230 V pumps (I needed the DC voltage booster - presumably adding energy losses). Apparently 3 phase works better. How much better ?
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
10,668
Solar inverters, if that means typically battery type and sometimes batteries optional meant to power loads, are single-frequency not variable. So unlike VFD, they won't ramp up motor speed. They will be expected to deliver locked rotor amps or about 5x running amps for a fraction of a second. If that exceeds their surge rating, they shut off.

I understand 3-phase motors draw a high surge current just like split-phase motors, but have better starting torque. So they could start and reach speed in less time, a shorter surge.

If you can get VFD that are able to accept PV input, that would seem attractive. Maybe it varies motor speed to maximize power harvesting from PV. Ideally it accepts a wide range of PV input like other MPPT.

The ones you mention with PV input - are those just AC input VFD, with additional terminals (and maybe additional diodes) beyond the 6 diodes of a typical VFD input? I've thought about tapping into my VFD for that purpose, let PV pull voltage higher than AC rail, so it supplies power when there is sun. Just make sure it can't backfeed DC into AC grid if a diode fails! (utility transformers wouldn't like that!)

If for single-phase not 3-phase it can't vary speed much because motor won't work well. I've seen VFD for single-phase, which used starting winding as 3rd phase. That said not to run below 80% of full speed except briefly.

One guy said that well pumps shouldn't be run with a VFD because they rely on a film of water, apparently a fluid bearing, and wear is excessive until they come up to speed. Grundfos sells a PV direct well pump, may or may not have avoided that issue. I would be inclined to avoid frequent cycling of a pump started with VFD; turn it on once when tank near empty and run until full, rather than cycling every time someone uses water.
 

Pemba

New Member
Joined
May 3, 2021
Messages
3
What I'm talking about is marketed as a solar inverter (SI), also solar pump inverter. What you're talking about I would call an ("ordinary") inverter. But my terminology might very well be off (wrong) . Output frequency is certainly variable with pump slowing down and speeding up as a bit of cloud passes by etc. Having said that, below 35Hz or so the pump struggles (as you seem to mention..) . In fact almost everything is adjustable. It also has terminals to connect level probes, pressure switches etc. It even has an external thingy that you fit with a SIM card to communicate with it. It produces three phase 230VAC (adjustable off course, it can also produce 110VAC). Most smaller pumps here are 230V single phase, with a Neutral and a Phase. The three output terminals of the SI are connected to Neutral, Phase and Capacitor (as mentioned above). It's quite possible that it doesn't work very well in the sense that that translates to loss of efficiency. That's what I'm trying to find out. The one I have is Chinese and the manufacturer has told me the 380V one works better. Grundfos and Schneider appear to have similar things and they all have three phase 380V output. I haven't looked into how they work internally. I just thought of them as a possibility to power an(y) ordinary pump with solar energy without having to use a battery. But the extra PV panels requirements are notable. Maybe that's different for the 3 phase 380VAC ones though..
 
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