Inverter requirement for a well pump

cdrichards2 · January 2018

Greetings ALL!
I've been reading, learning and lurking on this forum long enough, and it's time to field some inverter questions... :-)

I have a 300' deep well in a remote Colorado location with an unknown pump mfg, but I know it is a 3 wire pump, and has a Franklin Electric Power Box (2823008110).

The pump is currently powered by a portable 5kW gas generator, but I'm looking to replace it with a Magnum or Conex inverter (and related battery bank & solar gear) later this year.

Using a clamp meter, at startup I measured instantaneous surge current = ~45A Pk, and average run current = 11.2A

Questions:
1. Should I have any concerns on the Magnum MS4024PAE to keep up with the pump surge?

2. Conex has two models that I think should work: SW4024-120/240 and SW4024-230. I'm assuming it can be wired correctly so that the split phase 120/240v would work just the same as the single phase 230v inverter for this pump. Why does Conex offer two models?
3. Are there any other manufactures you'd recommend that could be used for this application?

Thanks a bunch!
Doug

mike95490 · January 2018

At least you have a 3 wire pump, they abuse inverters a little less than 2 wire do.
Because of my pump, I opted for a large 6Kw inverter, which handles it just fine.
From your description, it looks like you have 1.5hp 230V pump. Because of power factor,
I'd suspect your pump will pull about 3Kw from your inverter. My 1/2hp 240V consumes 1Kw as logged by my inverter.

Image: https://us.v-cdn.net/6024911/uploads/editor/zr/u2v2gpc6xzty.jpg

trungson · January 2018

Please keep me posted on your setup/results as I also have a well pump setup with generator and am thinking about having it powered by solar as well. Might be expensive though.

oil pan 4 · January 2018

It' got a 45 amp start? I' surprised the 5kw generator can over come that load.
Because power inverters are so expensive could you drop a lower HP pump down in the hole and put in a second surge tank?

WaterWheel · January 2018

I have a deep well (390') with the 1 1/2hp pump hanging 200' down. I can't see the initial start surge but when the 220v pump is running it's pulling about 2500 watts. The start up surge is probably around 7000 watts but I'm just guessing with that number

A lot of people run their wells off of a Magnum 4448 with no problem.

cdrichards2 · January 2018

Mike95490, Thanks for the info. I'd agree it looks like it's a 1.5hp motor.

Trungson, I'll be sure to post an update later this year on what gets implemented and any problems along the way.

OilPan4, first choice is not to pull the pump, but that is an option. What do you mean by a second surge tank?

My well is 300' deep and from the well report, the static pressure is 100', so I"m assuming that means the pump is 100' down. My challenge is the pump has to move the water up an additional 300' up the hill to a 200gal water reservoir at the house, so I was already sure it's a hefty pump. Could only measure instantaneous surge, but wish I knew the ~5s surge to get a better feel for inverter requirement.

Anyone have insights into why Conex offers both 120/240 and 230v inverters? From the specs, I don't see any advantage for the 230V model. Regulations?

mike95490 · January 2018

I think the 230V is a european standard. The 120/240 is north amercian split phase standard & can be wired for either. In 240V mode, it can only handle a certain % of imbalance between phases, so you can't hang all the loads on just 1 phase. And for pumping your water, you need the hp and 240V.

Does your 200 gal gravity feed your house, or is it a large pressure tank ?

cdrichards2 · January 2018

Thanks for the info. This inverter will only be for the pump, so there won't be imbalance issues to worry about.

And no gravity feed pressure to the cabin either. The well was drilled well down the hill (~1000' away), so water is pumped to a reservoir under the cabin, and a small secondary pump pressurizes the internal water system from there. My whole problem is to get the gas generator to and from the well, I have to drive ~5 miles around to get to it (every ~3 days). Hence the desire for a solar/inverter option.

mcgivor · January 2018

An option is a solar pump designed for the purpose, no battery, includes it's own 3 phase inverter. The total head is pretty high at ~400', but there are solutions, here is an example of one, randomly plucked off the web.
http://www.genproenergy.com/genpro-products-solutions/product-catalog/water/solar-pump-systems/ground-water-applications/ps1200-hr-04h.html

BB. · January 2018

Generally, 230 VAC is a 50 Hz inverter (120/240 VAC is usually 60 Hz).

In north America, 50 Hz is not usually not that useful (transformers, motors, etc. do not work the same if designed for 60 Hz).

Some inverters are programmable for 50 or 60 Hz.

-Bill

oil pan 4 · January 2018

You have a surge tank or pressure accumulation tank correct?
Or are you pumping to an open surface tank?

cdrichards2 · January 2018

Oilpan4,
the output of the pump in question goes up the hill to a non-pressurized containment tank.

oil pan 4 · January 2018

Then dropping in a smaller pump shouldn't be too much of a problem.

MichaelK · January 2018

I am always amused at reading something like "just pull the pump and replace it". Recommendations like that are made by people that have never pulled a pump hundreds of feet out of the ground and don't know how challenging that actually is. I'd say you're a lot better off building yourself an above-ground system that can handle what's stuck underground rather than the other way around.

I chose that route, and build a system with 4500 watts of panels and an XW6848 inverter. My 1.5hp 3-wire Grunfos well pump pulls 38 amps at startup and 10 amps running, and with panels in full sunlight, the XW starts the pump with ease. I can easily get 8 hours of pumping done per day, and that's with keeping the batteries full and floating. The graphics on the unit tell me that running the pump is only at 1/3 of the 6848's capacity.

I am little leary though; questioning the capacity of the SW4024. It's peak 5 second output is 41amps, right at what your pump is demanding at startup. Running equipment routinely at the ragged upper red-line might put too much stress on the electronics. Brand new, it might handle it once or twice, but routinely day after day, year after year, I would question it.

One option you have is pairing two SW4024 together. They will sync with each other and match their waveforms to double their capacity. Two SW4024's in parallel will actually be cheaper than a single XW6848, and be slightly higher capacity. It also has the added benefit of if a single component of either pair goes down, you can still limp on half power till replacements are installed. Two 4024's, each with it's own bank of batteries and solar arrays, I think could outperform my 6848.

About the Magnum, I called their technical support, and told them my starting/running amperages and they told me no, the Magnum wouldn't handle it.

oil pan 4 · January 2018

Mines only 120 feet down.
But with a 16 inch bore diameter well I can just drop another pump down there.
I'm probably going to end up having 3 down in mine. A 24v pump for solar. A 3/4hp 240v pump for day to day use and a 240v 3hp pump for agricultural. And possibly a 4th pump if my neighbor wants to lease my well, deal of a life time, $25 a month to drop a 1hp pump down there and run it as much as he wants, he supplies the power.

mcgivor · January 2018

@MichaelK said, I am always amused at reading something like "just pull the pump and replace it". Recommendations like that are made by people that have never pulled a pump hundreds of feet out of the ground and don't know how challenging that actually is. I'd say you're a lot better off building yourself an above-ground system that can handle what's stuck underground rather than the other way around.

Pulling a pump understandably is not as simple as it sounds, but from my understanding surface pumping has its limitations, around 100' for a 2 pipe jet pump, hense the need for a submersible pump for depths greater than this. As the OP has a static water depth of 100' and a 300' well, it would be reasonable to assume the pump is at a depth greater than 100', which is more than a surface pump is capable of, again just my understanding, by no means am I an expert in the field. Not being argumentative or critical, just curious as to what surface pump could be utilized for such an application, never know could learn something new.

oil pan 4 · January 2018

I have pulled my 120' deep well, water sits at 108' pump sits on the bottom. It sucks, but I don't really see what the big deal is.
I guess if you had a well service do your well for you and they used 20' lengths of pvc, then I guess you're sol.

peakbaggger · January 2018

Have you considered installing a Franklin Monodrive and get rid of the startup surge?

oil pan 4 · January 2018

How much do those cost?
I couldn't seem to find a price.

Inverter requirement for a well pump

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