12V Pure Sine Inverter for 240VAC Well Pump

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

Comments

  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    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.
  • mike95490mike95490 Title:User Posts: 6,201Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    steve wrote: »
    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/business/WaterSystems/Service/AIM/page-13.aspx
    ( new URL : http://www.franklin-electric.com/media/documents/M1479%20MDC%20Catalog.pdf )
    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 - 1,000W, depending on how clogged the filter is.
    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.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • SystemSystem Posts: 6,290 admin
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    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 :p 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
  • icarusicarus Super Moderator Posts: 5,070Super Moderators
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    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
  • AntronXAntronX New User Posts: 462Solar Expert ✭✭✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    Hey guys, can OP parallel two of Outback VFX2812 Inverters?
  • stephendvstephendv New User Posts: 1,571Solar Expert
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    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 AngeliniDave Angelini formerly Dave Sparks Posts: 1,957Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    stephendv wrote: »
    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!
    "we go where power lines don't" Sierra Mountains near Mariposa CA
     http://members.sti.net/offgridsolar/

  • mike95490mike95490 Title:User Posts: 6,201Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    VFD kits:
    http://www.automationdirect.com/adc/Shopping/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.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • mikeomikeo solar piddler Posts: 383Solar Expert ✭✭✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    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.
  • mike95490mike95490 Title:User Posts: 6,201Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    PS - If you end up changing to a 3 phase pump system, see what happens if you go with a smaller pump - can you manage with a 1/2 hp or 3/4, or do you really need 1.5hp ? Longer run time at slower rate is preferable to more starts, as long as you can keep up with the garden hose.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    AntronX wrote: »
    Hey guys, can OP parallel two of Outback VFX2812 Inverters?

    In theory this would work, but I wouldn't want to count on it. Outback for all their quality has a somewhat optimistic rating system and you may not get the full power needed to survive the starts. Plus you have to 'stack' them and use an autotransformer to get the needed output. And then there's the DC current rush to supply that 5 kiloWatts: over 400 Amps! That kind of sudden demand can overwhelm a battery bank.
  • AntronXAntronX New User Posts: 462Solar Expert ✭✭✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    ...And then there's the DC current rush to supply that 5 kiloWatts: over 400 Amps! That kind of sudden demand can overwhelm a battery bank.

    If the battery is large enough, this is not a problem.

    I have another idea. What if there was 25 Ohm wire-wound resistor in series with the pump motor? The combined motor + resistor resistance at stall would be 37 Ohms which equals to 1500W at 240V. This would be maximum inrush starting current. Then to apply full operating voltage to the motor, this 25 Ohm resistor would be shorted out by the relay controlled by time delay circuit. The delay could be set around 2 - 5 seconds, whatever time works best. I am not sure if this method would work with AC motor since I never tried it. I have small AC motor here to try out, so I will report back later.
  • AntronXAntronX New User Posts: 462Solar Expert ✭✭✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    Update on the resistor idea. It works! I connected three of 3 Ohm 50W Dale resistors in series for total of 9 Ohm 150 Watts, in series with Ryobi 120V 2.1A 3600 RPM benchtop grinder. It takes now 7 seconds for the motor to spin up to speed, instead of 2 seconds. Maximum power observed during startup was 600 Watts. Without resistors inrush power is 1500 Watts.

    Edit: attached diagram image:

    Edit2: This works well with free-wheeling motor, or with induction motor that is not under load when starting up. This method most likely will not work with submerged water pump.
  • mike95490mike95490 Title:User Posts: 6,201Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    AntronX wrote: »
    Update on the resistor idea. It works! I connected three of 3 Ohm 50W Dale resistors in series for total of 9 Ohm 150 Watts, in series with Ryobi 120V 2.1A 3600 RPM benchtop grinder. It takes now 7 seconds for the motor to spin up to speed, instead of 2 seconds. ....

    Is your well pump a 2 wire (with starting cap underwater, in the pump) or 3 wire, (with starting cap in control/relay box)? That will make a difference of where to place the resistor.
    If it uses a true relay, it's likely to work. If like my new one, with electronic relay, it may not work. Your mileage may vary.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • AntronXAntronX New User Posts: 462Solar Expert ✭✭✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    I am not testing this with the pump. I do not know if the grinder motor has electronic or relay start. This works with drill press and induction motor belt sander too. Friend of mine has 1 hp 120V pool pump that he does not use. I may try this with that pump under water load. But I expect the test to fail.

    Upon closer inspection of power / motor RPM curve, it looks like inrush power does not drop off until almost full motor speed. So, spinning the motor up to 1000 rpm and shorting resistor brings inrush power right back up to original. Which means that this method will not work with pump that is under water load. The motor has to freewheel for this to work well, otherwise rotor will not sync with rotating magnetic field if motor is under any kind of load while starting up.

    The inveter has to reduce the frequency of AC current to allow for rotor and magnetic field to sync. I think that would be better method of reducing inrush power. It should be possible to design or modify existing single phase inverter to do that and use it only with motors. Upon overload, inveter needs to drop the AC frequency and ramp it back up slowly. This is getting very close to what 3 phase VFD does.
  • stephendvstephendv New User Posts: 1,571Solar Expert
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    I'm using one of the low cost iDrives: http://www.imopc.com/products/71/idrive.html
    The borehole is 110m deep.
    Setup is: single phase 230V AC -> 25A breaker -> 2.2kW (max) iDrive -> 1.5kW pump.

    Mike, for my application, the only additional part I needed was the breaker or fuse. Didn't need a controller or reactors. The iDrive is a generic VFD to control any 3 phase motor load, so it doesn't include pump-specific controls, but it does have some input sensors which I connected to a water level sensor. When the well is empty, the drive will automatically shut down the pump to prevent dry running.

    Not sure if the iDrive is available in the America's but a quick google throws many results for "variable frequency drive".

    There are also models built specifically for pumps that might have some useful features:http://www.adlee.com/pump_variable_speed_drive.htm

    I used to have one that could control pump speed based on a programmed water pressure threshold, so it could be used to automatically provide a constant pressure source - was triple the price of the iDrive though.
  • Dave AngeliniDave Angelini formerly Dave Sparks Posts: 1,957Solar Expert ✭✭✭
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    Thanks for the testing and info! Sounds like this is still too early for prime time.
    I really need this to be mainstream and if i can't get it from Az. Viento y Sol then I will stay wth Induction and Franklin. Solstice tomorrow!
    "we go where power lines don't" Sierra Mountains near Mariposa CA
     http://members.sti.net/offgridsolar/

  • SystemSystem Posts: 6,290 admin
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    Hay guys a 4kw gen will run a 1/2hp pump (120 or 240 volt) just fine for a lot less money.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: 12V Pure Sine Inverter for 240VAC Well Pump
    b543965 wrote: »
    Hay guys a 4kw gen will run a 1/2hp pump (120 or 240 volt) just fine for a lot less money.

    Very true! :D
    And an often recommended procedure around here: run the gen, fill some pressure tanks, have water the rest of the day. Certainly better than trying to power a large pump from 12 VDC, no matter how big the battery bank.

    But if you want all "quiet power" some significant re-engineering is often in order. :cry:
  • peakbaggerpeakbagger New User Posts: 321Solar Expert
    Re: 12V Pure Sine Inverter for 240VAC Well Pump

    Goulds pumps have been selling packaged well pump variable speed drives for several years. I expect other pump manufacturers also sell packages. I dont think the pump is any different just the control box at the top of the well. With type of setup, they downsize the expansion tank substantially and maintain a constant pressure at the house rather than starting and stopping the pump at a high and low pressure setpoint.
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