Power inverter to power well pump?

[PissedOffAndAnnoyed]

I have a well with a 2hp submersible pump. It draws about 1.6kw @ 240v. I want to be able to power this during a power outage, but most inverters or generators that have 240v capability are absolutely huge and expensive.

I'm wondering if a generic foreign market 230v 50hz DC power inverter would work to run my pump? Would it just pump slower at 50hz? (that is OK) Is there any reason that wouldn't work since the it would be single phase power and not split phase like US 240v? I would not be using it for long periods of time, just enough for basic usage if the power goes out.

If that would work, what size inverter would I need in order to be able to start a 1600w 2hp motor? I have no idea what the startup rush is.

 

[mike93lx]

I have a 240v inverter generator that wasn't crazy expensive. Briggs q6500

You are going to need a big, big inverter and some serious battery power to run it. Most car alternators don't put out anywhere near that power at idle and many don't even max out that high, so you'll be running the car engine at 3k+,and drawing off battery

 

[PissedOffAndAnnoyed]

I don't need generator advice, please do not turn this into a generator/battery thread.

1600w at 12v is 133 amps. Most cars could handle that through a set of jumper cables for a few minutes, but I have other power sources. The well would not need to be used for more than a few minutes, this would be for emergency use only.

It does use a lot of power instantaneously to startup, but that is very short, and the subject of my question.

 

[mike93lx]

Your username seems applicable. You mentioned the cost of a generator, so I made a quick comment addressing that.

Good luck

 

[Ole Slewfoot]

Get an adequate tank to gravity feed during outages. You will never regret it.

A 2k/4K 230 inverter is under $100 on alibaba, and probably equivalent quality to the 3k harbor freight unit that pulls down the starting batteries in my diesel truck in a couple minutes at full load.

 

[PissedOffAndAnnoyed]

Is it really so hard to stick to the question? No, I am not installing a water tank. I asked a very simple question...
1. What is the minimum size power inverter to handle the startup current from a 2hp motor?
2. Is there any problem running a normal 240 60hz motor on 230v 50hz?

 

[Ole Slewfoot]

P=I/E

 

[PissedOffAndAnnoyed]

You're clearly not understanding the question. A power inverter needs to be oversized compared to the load when running an electric motor. A 2kw inverter would not start a 1.6kw motor. The question is, what is the minimum size that would? It's not something you can just calculate.

If you don't have an answer please just hit your back button.

 

[RPH]

Location would help. In North America 60 Hz is standard. If the pump is dual rated for 50 or 60 hertz then you be ok, slight loss of power. How ever if it’s 60 Hz only the pump will be very unhappy and will tend to cook itself to death. I have lots of experience sending power tools to Europe for projects. All worked and all were dead or close to death when done. None came home.

 

[PoorUB]

I know you don't want to talk generators but i am tossing this out as an example, when sizing a generator for a motor load we always went 2-1/2 to 3 times the amp out put for starting load. I would assume and inverter would need to to be sized similarly. so that turns your 1600 watts into 4800 watts. I also would find specs on your pump and use that information for sizing, as we always went off the nameplate for sizing, not the actual current draw. I would assume a 2 HP motor at full load is closer to 2400 watts so that would put your invertor at 7200 watts. 7200 watts at 12 volts will be 600 amps. You will need a good sized battery!

As for the 50 hertz invertor, I wouldn't try it unless the motor is rated for it, it might be.

 

[American Locomotive]

Your question is not answerable without your pump's full datasheets from the manufacturer. Generally speaking, a motor will typically draw ~4x-5x its running current during startup. Goulds Pumps say their 2HP 4" submersible well pump has an LRA of about 45A. So that means during start-up, you can expect a 45A inrush - or about 11KW.

Your plan to use a 50Hz 230-240v inverter makes this issue worse. At 50 Hz, the impedance of the motor's windings will be lower, which means more current will flow. So the motor is going to draw more current than it normally would during start-up - about 20% more. So realistically your inrush will be up near 55-60A. At 50Hz, the pump will also spin 20% slower. The maximum pressure a centrifugal pump makes is based on the square of the pump's speed. So a 20% reduction in pump speed is going to reduce your maximum pressure potential by about 40%.

But your math for your power consumption is also going to be off. A 2HP motor is really only going to be about 85% efficient, so realistically it's going to be drawing more like 1800W in operation, and with a 85% inverter efficiency - that's 2.1KW input.

This isn't a workable plan for a variety of reasons.

 

[cstmg8]

50hz, just nope. Well explained above.
So, assuming you're going with a 60hz inverter, you need a MINIMUM of 4,000w (2.5x)for startups. That's definitely the low end. 1.6kw ÷ 240v = 6.6amps where did you get your info, motor data tag? Is it FLA?
If you're dead set on an inverter, have you thought about adding a soft start to your pump motor? It should reduce your starting current and allow a more reasonable inverter.
Something like this, I haven't done any research to see if this one will work for you:

Ferguson Home | Shop All Generators

Find the right generator for the job with these top brands!

www.electricgeneratorsdirect.com

 

[nadogail]

IMHO, There is no inexpensive way for the OP to start and run his pump from an inverter.

 

[mike93lx]

IMHO, There is no inexpensive way for the OP to start and run his pump from an inverter.

Agreed. Generator would be easy though

 

[Captain Spaulding]

Since you don't seem to have a clue about how to be remotely polite, the idea of using a 50Hz inverter on a 60Hz pump is stupid, and the idea of using any inverter to power a well pump isn't much better. Anyone who thinks either of those is remotely practical should be appreciative of any suggestion because it's virtually impossible to come up with a worse plan.

 

[u2slow]

I work on a 50Hz jobsite... we have miserable luck with 60Hz motors. They need to be dual-rated to work under load.

I have an 1800W 120v inverter also. It will not start the little $100 air nailer compressor I have. The inrush characteristic of the motor is too much.

The gravity-tank/cistern is the way to go.

 

[wyliesdiesels]

running a well pump from an inverter and batteries is a fools errand. you havent even told us how deep the well is which will effect things here too (ie. how much head of water in the riser pipe the pump has to push up on startup). then you want to add in 50hz... this is a disaster in the making...

 

[Showkey]

Pissedoffandannoyed has left the building and the discussion ?

 

[mike93lx]

Pissedoffandannoyed has left the building and the discussion ?

A tragedy.

Hell of an entrance to a forum asking for help

 

[tyme2par4]

Since you don't seem to have a clue about how to be remotely polite, the idea of using a 50Hz inverter on a 60Hz pump is stupid, and the idea of using any inverter to power a well pump isn't much better. Anyone who thinks either of those is remotely practical should be appreciative of any suggestion because it's virtually impossible to come up with a worse plan.

There's nothing wrong with using an inverter to power a well pump. There are plenty of large inverters that would handle it, but they are going to be expensive.
You can get a 6kW 60Hz 240V split phase inverter for $1500. The question that needs to be answered is what is the starting load of the pump? Aims claims their inverter can surge up to 18kW for 20 seconds, so it would probably be up to the task. But this is a 24V inverter, so you aren't going to be able to run it off a car battery.

 

[WisJim]

Our over 22 year old Trace SW4024 inverter runs our submersible pump just fine, in a well that's about 130' to water. But the inverter can put out over 9kw momentarily as in motor starting loads, and it's big and heavy, and cost about $3k back when I bought it. Small and cheap won't do it.

 

[Norcal]

The OP’s forum name is a big clue from my read so far.

 

[mike93lx]

Our over 22 year old Trace SW4024 inverter runs our submersible pump just fine, in a well that's about 130' to water. But the inverter can put out over 9kw momentarily as in motor starting loads, and it's big and heavy, and cost about $3k back when I bought it. Small and cheap won't do it.

What's the hp on that pump? My last house had the pump at 125' and it was 7gpm and only 1/2 hp.

What are you using for batteries and chargers?

 

[Shiftless]

Our over 22 year old Trace SW4024 inverter runs our submersible pump just fine, in a well that's about 130' to water. But the inverter can put out over 9kw momentarily as in motor starting loads, and it's big and heavy, and cost about $3k back when I bought it. Small and cheap won't do it.

I bet you have an impressive bank of batteries to back that up.
Maybe 8 six volt golf cart batteries wired up in series parallel ?

 

[alfredeneuman]

The NEC table shows a 2HP, 1Ø, 240V motor's full load as 12A, not 1.6kw @ 240v (6.6A)
The least load I can find is a SPL(Special) 2HP motor that draws 7.5A

 

[WisJim]

To answer the questions about my well pump, inverter, batteries etc., we have a set of 1500 amp hour 2 volt lead acid cells, similar to large fork lift cells, about 200 pounds each, 2400 pounds or more total. They were new in 1999 and are reaching the end of their useful life. The pump is a half horse unit. The system is charged by 7.4 kw of photovoltaics and a 2.5 kw wind turbine and we have grid connection for backup. The wind turbine is a Jacobs from the 1940s (rebuilt in 1977 and due for bearing renewal soon), and our oldest PVs were bought in 1981 or 82, and still work well.

 

[mike93lx]

To answer the questions about my well pump, inverter, batteries etc., we have a set of 1500 amp hour 2 volt lead acid cells, similar to large fork lift cells, about 200 pounds each, 2400 pounds or more total. They were new in 1999 and are reaching the end of their useful life. The pump is a half horse unit. The system is charged by 7.4 kw of photovoltaics and a 2.5 kw wind turbine and we have grid connection for backup. The wind turbine is a Jacobs from the 1940s (rebuilt in 1977 and due for bearing renewal soon), and our oldest PVs were bought in 1981 or 82, and still work well.

Sounds like a really neat setup. I imagine you have a good chunk of coin in all that.

Do primarily run your whole home off that setup?

 

[American Locomotive]

The NEC table shows a 2HP, 1Ø, 240V motor's full load as 12A, not 1.6kw @ 240v (6.6A)
The least load I can find is a SPL(Special) 2HP motor that draws 7.5A

The NEC motor tables are pretty old and outdated these days. They're basically worst-case-crusty-ancient-motor. They still rate a 5HP 3-phase motor at 15.2A for example. It's not even legal to sell a 3-phase motor that inefficient anymore. They spec 28A for single phase 240v 5HP motors, when most of them these days are down around 20-21A (or even a little lower for the very best motors).

 

[larry_g]

SubDrive Connect Plus

The SubDrive Connect Plus™ Variable Frequency Drive is built to provide a constant water pressure solution in applications that utilize three-phase motors.

franklinwater.com

You may find that a Monodrive controller from the above link will solve your problem. I have a sub drive and it will start fine on a regular generator. These have a 'Soft start' feature that does away with high inrush current.

lg
no neat sig line

 

[u2slow]

The NEC motor tables are pretty old and outdated these days. They're basically worst-case-crusty-ancient-motor. They still rate a 5HP 3-phase motor at 15.2A for example. It's not even legal to sell a 3-phase motor that inefficient anymore. They spec 28A for single phase 240v 5HP motors, when most of them these days are down around 20-21A (or even a little lower for the very best motors).

That's not strictly efficiency. On single-phase motors, capacitors are the main reason for these lower FLAs.

 

[theoldwizard1]

SubDrive Connect Plus

The SubDrive Connect Plus™ Variable Frequency Drive is built to provide a constant water pressure solution in applications that utilize three-phase motors.

franklinwater.com

You may find that a Monodrive controller from the above link will solve your problem. I have a sub drive and it will start fine on a regular generator. These have a 'Soft start' feature that does away with high inrush current.

This is the key to running a pump off of either an inverter or generator !

There are after market "soft starters" like the one from Micro Air that really work. You do NOT want a "hard start" kit !

 

[Williams B]

I have a 240v inverter generator that wasn't crazy expensive. Briggs q6500

You are going to need a big, big inverter and some serious battery power to run it. Most car alternators don't put out anywhere near that power at idle and many don't even max out that high, so you'll be running the car engine at 3k+,and drawing off battery

Same one with me.

 

[alfredeneuman]

The NEC motor tables are pretty old and outdated these days.

I know that...That's why I added the severely overrated SPL motor @ 7.5A.
Can you find a 2HP that draws less than that? He claimed it's 6.6A

 

[Metal-Marc]

A tragedy.

Hell of an entrance to a forum asking for help

Forgot his meds...

 

[mike93lx]

Forgot his meds...

He knew what he was about when making that user account.

Maybe he'll create a new one and start over