4" submersible pump motor 3phase 230v 4 pole

[bnelson]

Does anyone know who makes a submersible pump motor with these specs;
1/2 hp
230v
1750 rpm
4 pole
4" (like a Franklin 4" sub motor)

I am trying to find a motor to operate a down hole progressive cavity pump.

All of the pump manufacturers that I have come across only make a 2 pole 3450 rpm motor.

thanks.

 

[bklauba]

Flygt has several models that fit your specs (as far as they go).

What kind and % of solids are involved? Are we talking single or 3 phase 230 VAC??

BK

 

[bnelson]

I will be pumping water from a water well...no solids.

The motor needs to be 3 phase as stated in the heading.

I would really like to find a permanent magnet type of 3 phase motor or a brushless permanent magnet dc motor...but will settle for what ever I can find.

 

[bklauba]

Take a look at:

http://www.franklin-electric.com/CatalogSubmersible/search_menu.aspx

As far as a PM/3ph motor goes, do you have a drive for such, or are you planning on adding one?

BK

 

[bnelson]

I have thoroughly reviewed the Franklin web site, and I still can not find any thing but 2 pole 3450 rpm motors. I am looking for a slow speed high torque motor.

Yes, I can build my own motor drive controls but I need a motor! A submersible 4" motor with 0.9 ft/lb of continuous torque (0.3 hp @ 1750 rpm).


I can simply oversize the 2 pole motor and run it at a slower rpm but that is alot of wasted power...and this will be a solar powered application...so I need as much efficiency as possible.

 

[bklauba]

Wasted power? not exactly.

You are right, by oversizing the motor (1 HP), you could run it using an inverter at half speed, but the power consumed would be roughly 1/2 HP. There would be a little extra power consumed turning a slightly heavier rotor. There would be a little (like 5 - 7% of output power) diss'd as heat by the drive. Is loss of ~ 20 - 30 watts going to be a problem?

Other advantages of using an inverter include supplying balanced voltages to the motor, and rather good motor protection. Prices on these things are pretty reasonable, not a lot more than what a starter with O/L would run. Take a look at KB Electronics chassis style inverters, for one choice.

BK

 

[bnelson]

I may be wrong, but wouldnt a smaller 4 pole 3 phase ac induction motor running at 60hz consume less power than a 2x larger 2 pole motor running at 30hz with the same load?

Also, I will need this motor to start at frequencies of around 2-3 hz (early in the mornings, late afternoons, and when there is some cloud cover) and ramp up as the power from the solar modules increased. I can build the freq. drive, but I need a motor.

I was thinking that there was quite abit of heat loss in an ac induction motor running at very low freqencies.

Also, the fact that the motor would weigh half as much would be a great advantage in hand installations.

So, back to my original question, does anyone know of a water well pump motor manufacturer that makes a 4 pole 1/2hp motor?

thanks,
bnelson

 

[BJC]

Most solar applications use DC motors.
The lift (head) any centrifugal pump generates is proportional to the square of it's speed. A pupm running at 2-3 hz may not get the water out of the discharge pipe.
Downhole well pumps are high RPM, multistage because thats the what it takes to get the water out.
A 4" inch pump running at 1750 rpm would have approximately 1/4 the head of a 4" pump running at 3500 rpm.
How much water you move is dependant on the pump curve. You need to check some pump curves.

 

[edison123]

bnelson,

It is not easy to fit four poles in the small diameter of submersibles, hence the 2 pole motors are standard.

At 2-3 hz, I don't think your pump is going to do any work. You seem to be working on an interesting project. So, pls verify all data.

 

[bnelson]

I am wanting to power a POSITIVE DISPLACEMENT progressing cavity helical rotor pump that requires 0.28hp @ 1750rpm.

This equates to 0.84 ft-lbs of torque (the torque remains constant regaurdless of rpms).

THIS IS NOT A CENTRIFUGAL PUMP!! This is a positive displacement pump meaning that for every single rotation of the pump, it will pump a given amount of water....kind of like a medical syringe, for every 1 cc that you push the plunger, you get 1 cc no matter how fast you push it.

I am looking for a 4 pole motor so that I wont have to operate a 2 pole motor at very low frequency.

I realize that most solar applications utilize a dc motor, but I am looking for a very long life motor...NO BRUSHES...also the motor has to be able to be submerged...not a great selection of DC brushless submergible motors on the market. So, I am wanting to utilize an "off the shelf run of the mill" motor. I figure that surely someone makes a 4 pole AC submersible pump motor, but maybe not.

 

[bklauba]

The rule of thumb is to not run a 3 phase motor much below 30% of the line freq., for the reasons sited. That would be about 500 RPM for a 1750 RPM motor. This is still ~ 3 times your req't of 2 - 3 Hz (120 - 180 RPM). DC might be the way to go.

Options:

1. Brush life at such low speeds is much longer than at rated speeds.

2. Brushless DC. There are a number out there. I have used Emoteq/Hathaway (motors, don't care much for their drives.)

You can buy the Emoteqs (and others) either housed or houseless, so you could build a submersible housing around such a motor, mating with the pump. The size 34 frame from Emoteq comes in a variety of voltage/speed forms. Check out

http://www.emoteq.com.

Other firms you might want to look at are SL Montevideo (

http://www.slmti.com)

and Minarik Electric.

BK

 

[coastpumpguy]

Good afternoon.
I can't say that I have ever seen a 1/2 hp 4" 4 pole sub motor but I do know that hitachi among others produces 4 pole motors in 6" sizes and up. I think the lower end of the range is 3 or 5 hp though. These are available in an oil filled or water filled version and are very proven in water well applications.
I would like to make a very important point. All of these type ( water well) motors use a kingsbury style thrust bearing which requires a very fast acceleration to a specific min speed to build the fluid film.If you ignore this,the thrust bearing will fail RAPIDLY.
For instance franklin specs 30hz in 1 second max, then you can ramp up from there.
I think the north american dist for hitachi is still sun star electric in texas.
You are probably aware but I will mention that grundfoss packages complete solar power pump systems based on high speed submersibles and integrated control schemes. Might be worth a look.

Hope this is helpfull and good luck.

 

[mc5w]

I think that you should use a conventional centrifugal pump and use the early morning and late afternoon solar cell output to charge the overnight batteries. In the middle of the day you would run the well pump full blast to charge up your water tower or clear water cistern.

A progressive cavity pump is going to have tremendously high friction compared to a conventional well pump. You can get the same amount of water using a conventional pump for a shorter period of time and also use less kilowatthours.

If your well does not have enough GPM to keep up with a fast pump for 6 hours per day, you can program your battery controller to run the batteries all the way down using the well pump during the 1 or 2 hours before the solar panel reaches full output. However, it might be cheaper to drill a second well and a second pump than to use bigger batteries.

With a 230 volt pump an inverter or VFD needs a 330 volt minimum bus voltage which would need to be the output voltage of your solar panel.

If this system is installed in a house your battery voltage is legally restricted to 48 volts.

 

[mc5w]

I found a line of packed pumps and inverters for use on solar photovoltaic power. The website is

http://www.dankoffsolar.com

. They are a division of British Petroleum. This would be worth a look before reinventing the wheel.

 

[akselj]

Have you considered Grundfoss

http://www.grundfoss.com/

they have pumps with built-in frequency converter, that might solve your problem.

 

[mc5w]

I think the Grundfos is spelled with 1 s.