12V Pure Sine Inverter for 240VAC Well Pump

[Steve]

Hi,

Can anyone recommend a 12VDC pure sin wave inverter capable of powering a 240VAC submerged well pump? Well pump current at 240VAC as measured by Fluke 337 true RMS clamp meter is 6.4 Amps operating and inrush or startup current is 18.8 Amps. Operating Watts is 1536 (6.4 Amps x 240 VAC) and startup Watts is 4512 (18.8 Amps x 240 VAC).

Inverter will only run well pump no other loads and a charge controller is not needed. I’m assuming a 12VDC 3000W with 6000W surge pure sine inverter 240VAC output would fit my application. 24 or 48 VDC is not an option inverter must be 12 VDC. I have located cheap non UL rated inverters that fit application but I’m looking for a name brand inverter with UL rating but so far have not located an inverter meeting above specifications. Thank you in advance for any recommendations.

Steve

[Cariboocoot]

In my opinion (and everyone can feel free to disagree with me) this is too heavy a power requirement for a 12 Volt inverter. The start-up current would require a 5-6 kW inverter, which just don't come in 12V. Not pure sine, anyway, and you are right to want sine wave for the pump motor. Never rely on an inverter's surge rating for anything.

Why are you stuck with 12V if this is a stand-alone set-up?

Pumping water is hard. One of the most difficult tasks to try and accomplish off-grid.

[mike90045]

Originally Posted by Steve

24 or 48 VDC is not an option inverter must be 12 VDC. I have located cheap non UL rated inverters that fit application but I’m looking for a name brand inverter with UL rating but so far have not located an inverter meeting above specifications.

There are none. 12V systems cannot handle the wattage needed to start the pump.

Your 18A @ startup is about half the actual starting current, your meter is not capturing the starting peak.

But using 18A @ 240V = 4320 watts @ 12V = 360 amps A couple of weeks of that several times a day, will shake all the lead off your battery plates.

As an example, I just installed my 1/2 hp well pump, on 240V, from an XW6048 inverter, with #6 ga alum wire for 400' one way distance. The inverter runs it flawlessly.
Motor spec is here: http://www.franklin-electric.com/bus...M/page-13.aspx
it's the 240V 3 wire # 214505 At normal loads, it's only 62% efficient, and power factor of .73 My inverter metering shows it pulls 950W.
Most other pumps will be comparable, Franklin is the gold standard of well pump AC motors. Inverter barely hums and gets warm.

Any idea what your run times for the pump will be? 10 min cycles, all day long, or 3 hours, once a day ? Your inverter and battery bank will have to be able to stand the load.

[Steve]

Hi Cariboocoot,

> Why are you stuck with 12V if this is a stand-alone set-up?

Current system including PV panels, chargers, two pure sine inverters, battery monitor, and batteries are configured for 12V. I do not want to implement a separate system to support 24 or 48 Volts.

Thank you,

Steve




Hi mike90045,

>There are none. 12V systems cannot handle the wattage needed to start the pump.

From my search that is the same conclusion I arrived at but thought I would ask as a last resort.


> Your 18A @ startup is about half the actual starting current, your meter is not capturing the starting peak.

Fluke 337 has a 100 mS inrush capture capability. I would think 100mS is quick enough to capture a realistic startup current. I performed the inrush test five times and used the highest reading, readings ranged between 17.9 and 18.8 Amps.


>But using 18A @ 240V = 4320 watts @ 12V = 360 amps A couple of weeks of that several times a day, will shake all the lead off your battery plates.

Battery bank is six 12V Optima Yellow Top D31Ts in parallel. I have run a 1500W pure sine wave inverter drawing 87 Amps in ten minute intervals from a single D31T with no problems.


>As an example, I just installed my 1/2 hp well pump, on 240V, from an XW6048 inverter, with #6 ga alum wire for 400' one way distance. The inverter runs it flawlessly. Motor spec is here: http://www.franklin-electric.com/bus...M/page-13.aspx it's the 240V 3 wire # 214505 At normal loads, it's only 62% efficient, and power factor of .73 My inverter metering shows it pulls 950W. Most other pumps will be comparable, Franklin is the gold standard of well pump AC motors. Inverter barely hums and gets warm.

Nice system! The XW6048 48V input certainly helps Thank you for the information on the Franklin well pumps.


> Any idea what your run times for the pump will be? 10 min cycles, all day long, or 3 hours, once a day ? Your inverter and battery bank will have to be able to stand the load.

Use is grid outages only which is rarely. Cycle time is about ~ 3 minutes. Grid down conserve mode we would limit well pump to five or six cycles per day.

Thank you,

Steve

[icarus]

What about a 12 vdc pump? Smaller pump, drawing fewer amps over a longer time, might be more efficient net/net. How deep is your well? How much water do you need per day?

Tony

[AntronX]

Hey guys, can OP parallel two of Outback VFX2812 Inverters?

[stephendv]

You can use a variable frequency drive (VFD) and a 240V 1.5kW 3 phase pump - this will mean NO inrush current as you can program the VFD to ramp to full speed very slowly. I use one with my 1.5kW well pump and it works great - cost about 200 Euro's.
Plus, you get to use a 3 phase pump which is likely to last longer, especially if it starts up slowly with the VFD.
So if you go this route, then you only need to size the inverter for 1.5kW continuous and don't need to worry about start surge.

[Dave Sparks]

Originally Posted by stephendv

You can use a variable frequency drive (VFD) and a 240V 1.5kW 3 phase pump - this will mean NO inrush current as you can program the VFD to ramp to full speed very slowly. I use one with my 1.5kW well pump and it works great - cost about 200 Euro's.
Plus, you get to use a 3 phase pump which is likely to last longer, especially if it starts up slowly with the VFD.
So if you go this route, then you only need to size the inverter for 1.5kW continuous and don't need to worry about start surge.

Please give us some links! Does Arizona Wind and Sun sell a VFD? How deep of a well do you have? Thanks!

[mike90045]

VFD kits:
http://www.automationdirect.com/adc/...Catalog/Drives

You will need for your 3 phase pump motor:
Controller
reactors/filters
Fuses & spares

I'd looked into this months ago, and by the time I had all the parts selected, I went back to a conventional 1/2 hp pump and standard controller. Can't even tune it up with a run cap - the start relay won't deal nicely with it. But it works.

[mikeo]

Use is grid outages only which is rarely. Cycle time is about ~ 3 minutes. Grid down conserve mode we would limit well pump to five or six cycles per day.

This is the set up I have except I use an SW4024 inverter through a 5KW 120/240 transformer that I picked up off EBAY for about $100, $60 of the price was shipping. It is not the most efficient setup but works well with my 1/2 hp 240 volt submersible well pump, also uses the Franklin motor. No problem with starting surge, lights do flicker a moment when the pump kicks on.