Move away from Brushed Pumping motors?

jonr · April 2014

[moved from original thread: http://forum.solar-electric.com/showthread.php?22792-Small-demand-pumps-and-their-brushes-who-knew&p=187809#post187809] -Bill B.

Interesting. I use a 120VAC Shurflo pump but run in from 75VDC (direct from panels) in an attempt to get more life from it (I pump 10 hours/day, 365 days/year for irrigation). But it's only been a month and it sounds like I am going to have problems.

I wonder if adding TVS diodes across the supply wires would reduce arcing. Or more importantly - what is a good solution? Perhaps some type of BLDC motor plus a small piston pump? That won't be cheap. 12V is out because of the very long distance to the pump.

BB. · April 2014

Re: Small demand pumps and their brushes... who knew?

For long term operation, you need to get a Brushless DC motor for your application.

Brushes will only last a few thousand hours before they wear out. And the commutator will need cleaning/turning occasionally too.

For a true DC powered pump system--you are probably looking at $1,000 - $2,000+ for a good quality pump assembly. There are quite a few out there--And we can make some suggestions if needed.

For irrigation, there is a new method that is becoming more available--Basically DC input VFD's (variable frequency drives) connected to 3 phase motors (or variations of Permanent Magnet DC motors, single phase AC motor with remote starting capacitor--basically 2 phase motors) and such.

I am not as informed on VFDs and DC input VFDs as I would like (don't need them, so just an "academic" interest at this time). We have a couple folks from overseas that are doing this now, and a fair number of Chinese mfg. of "solar powered VFDs" come up in web searches.

BB. wrote: »

Some discussions about VFD (Variable Frequency Drives)... Basically a variable frequency inverter with (typically) three phase output. Used to soft start motors (handy for 3 phase well pumps, or pumps with well head starting capacitor) and can also turn an AC motor into a variable speed motor (very handy for pumping applications).

WELL PUMP and Inverter QUESTION
Wind/solar for large scale pumping etc (out of my depth!)
could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC (new link/thread 10/27/2012)
Help required to design off grid system (information on possibilities to connect "standard VFDs direct to solar panels) (new link 1/13/2013)

We have at least one or two Well Drillers here that can probably give you some knowledgeable pointer here too...

In the end, it is all about the application... How high of lift, how many gallons per day, in-well pump, submersible, surface pump, etc... All those will help give you more exact information in support of your needs.

Towards that end I will move your questions to your own thread to keep the discussion focused on your needs.

-Bill

stephendv · April 2014

Re: Small demand pumps and their brushes... who knew?

Someone posted a new link to a solar direct VFD from schneider: http://www.schneider-electric.com/products/ww/en/2900-motion-drives/2945-specialized-drives/61444-altivar-312-solar/ which you can use with normal 3-phase pump.

jonr · April 2014

Re: Small demand pumps and their brushes... who knew?

Here is most of what I've learned:

Shurflo does make a brushless motor pump - the 8075-192-319. It would require that I use a DC->DC converter to convert my 75V down to the 24V it needs. I would still need to replace diaphragms. Not clear if one can reduce output (and pump wear) by reducing voltage (say to 20V). Max pressure output is about what I need (over 100 psi). Draws about 50 watts at this pressure.

I agree, VFDs have become common and inexpensive. Typical ones (non-solar) accept single phase 240VAC as input*. They output 3 phase 240 VAC and the speed and torque of the motor are manually controllable. I see many 240 VAC 3 phase motors from 1/6 HP and up. Not quite as energy efficient as permanent magnet motors and I think they lose quite a bit of efficiency if you operate at reduced power (say 1/10 HP which is about the amount of solar power I have).

I'm looking into using an ECM (brushless DC) furnace fan motor (1/2 to 1/4 HP) and running it at reduced speed and load. These permanent magnet motors are quite efficient over a larger range and have long life.

For pumps, it looks like most are using Procon vane pumps. Seems like a good choice as long as the water is filtered.

* - they rectify the 240AC to DC, so feeding it with 340V DC should work too.

Dave Angelini · April 2014

Re: Move away from Brushed Pumping motors?

jonr wrote: »

[moved from original thread: http://forum.solar-electric.com/showthread.php?22792-Small-demand-pumps-and-their-brushes-who-knew&p=187809#post187809] -Bill B.

Interesting. I use a 120VAC Shurflo pump but run in from 75VDC (direct from panels) in an attempt to get more life from it (I pump 10 hours/day, 365 days/year for irrigation). But it's only been a month and it sounds like I am going to have problems.

I wonder if adding TVS diodes across the supply wires would reduce arcing. Or more importantly - what is a good solution? Perhaps some type of BLDC motor plus a small piston pump? That won't be cheap. 12V is out because of the very long distance to the pump.

If distance is the issue (long wire run) why don't you power the pump at the garden with a solar panel and electronic pump driver circuit. Or, just a 12V battery and a solar panel?

jonr · April 2014

Re: Move away from Brushed Pumping motors?

There are so many trees down by the river that it would be hard to put solar panels there. Plus there are some security concerns. So the panels are at the top of the hill. With the current 75V system, it works fine with 1/2" pipe (600' long) and thin wire. The power draw and the flow are very low. I use no electronics - the panels feed the pump directly. I prefer to avoid a battery due to cost and longevity issues.

No doubt I'm going to have to do something more complicated and more expensive if I want long life.

jonr · May 2014

Re: Move away from Brushed Pumping motors?

I purchased a Genteq Evergreen IM motor. This is a 1/4 to 1/2 HP ECM motor intended for furnace fans (> 80,000 hour rating). There is a DC, brushless, permanent magnet motor with electronics inside to control it. Slow start (no big current surge). Various jumpers for different speeds and current draw. Normally this is powered with either 240VAC or 120VAC, but I'm going to try DC. Draws about 50 watts the way I have it configured. That's a good match for my solar panels and the amount of water I need.

Now I need to make or buy an adapter/faceplate to mount a Procon vane pump.

jonr · May 2014

Re: Move away from Brushed Pumping motors?

I found sources that provided these rough figures:

Diaphragms, e.g. PTFE: up to 20,000 hours
Pump valves: up to 8,000 hours
Hydraulic valves/pistons: up to 30,000 hours
Crankshaft bearings: 70,000 hours
Motor bearings: 50,000 hours
Crankshaft casing: failsafe
Brushes (DC motors): 2000+ hours
My motor: 80,000 hours
Procon vane pump: ???

Does anyone have data as to how long the diaphragms in a typical Shurflo style pump last? I've heard "yearly replacement".

jonr · May 2014

Re: Move away from Brushed Pumping motors?

I ordered a Lovejoy coupler from Zoro (1/2" to 7/16"). Fits perfectly. Now I need to cut off the motor shaft (it's longer than needed) and make some spacers to allow the Procon pump to be mounted to the faceplate of the motor. I still haven't seen any data as to how long a Procon vane pump might last before it needs maintenance.

Dave Angelini · May 2014

Re: Move away from Brushed Pumping motors?

jonr wrote: »

I found sources that provided these rough figures:

Diaphragms, e.g. PTFE: up to 20,000 hours
Pump valves: up to 8,000 hours
Hydraulic valves/pistons: up to 30,000 hours
Crankshaft bearings: 70,000 hours
Motor bearings: 50,000 hours
Crankshaft casing: failsafe
Brushes (DC motors): 2000+ hours
My motor: 80,000 hours
Procon vane pump: ???

Does anyone have data as to how long the diaphragms in a typical Shurflo style pump last? I've heard "yearly replacement".

With most any pump it depends on how much use, pressure set-points, and water purity. The bad part of the nitril diaphragm in the shurflo is when it leaks it often gets into the motor. I ran them on my sailboat and we changed it yearly to avoid failure at the wrong time. They could go years but...
They made the extreme series smart sensor for years that would do 60 psi and 5.7 gpm. It had the same problems that their marine and rv pumps had. They just never took the design as serious (like the kind of hours you listed above) for home use offgrid.

Move away from Brushed Pumping motors?

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