AboutWill Expertise Three phase electic motors, controls and related problems or failures, three phase motor installation issues, performance issues, connections, data and duty cycle information. All other electic motors. Specialty motors, repair concerns, performance concerns, obsolete motors and solutions. Other specialty equipment issues. Lost nameplate data and identification, lost connection data.
Also DC motors of all types.
See my profile under Home/electrical at this site
Experience 30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.
Organizations EASA, IBEW [retired], other specialty organizatons, Lubrication, Vibration EDI, Triboelectric Councils
Publications Currently fielding concerns at this site under "Home Electrical"
Education/Credentials 4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.
Expert: Will Date: 5/14/2008 Subject: Looking for a motor
Question QUESTION: Will, I have been searching the internet for a motor to provide a proof of concept I am trying to do. The motor should have the following attributes.
1. Variable speed adjuster starting off slow and allowing me to take to the maximum power that will allow the motor to run at it top speed.
2. Should be reversable with a switch e.g. when I need it to it should stop and immediatley start running in the oposite direction at the same variable speed setting it was left on.
3. For proof of concept the motor should be able to be plugged into a standard 110 outlet.
4. The motor can run at at somewhere at 2,500 RPM so I am not concerned with the HP.
Will I am not a motor expert by no means so forgive my ingorance. Any other information you may need please feel free to ask.
Thank you
ANSWER: Gil,
a couple questions, one is there a need for low speed high torque, what is the application in general, are you looking for DC, or AC [either can be plugged into a wall outlet with either rectification or variable frequency, what HP, and what is your budget?
It can be done, and when it reverses, are we talking instantly reversing, in other words when it stops in one direction it AlWAYS Reverses , or do you just need it to reverse and come up to the same RPM, depending on the situation?
This can be done, just some more ideas you have in mind will help, and I will help you fill in the blanks.
Will
---------- FOLLOW-UP ----------
QUESTION: Will, thanks a million for getting back to me. Ok this is proof of concept so you can have the big picture. I along with a friend are into aquaculture and as part of that business there is something called BIOFILTRATION (many types) but the one we are into is call SAND FLUIDIZATION. Without a long course in biofiltration. In this concept fine sand is kept fluidized e.g. suspended in water through good water pressure at the bottom. The short of it is dirty water comes in at the bottom clean water out the top. The problem is keeping water pressure regulated and constant.
In our small proof of concept a 55 gallon plastic drum would be used filled with water almost to the top with 1/3 of filled with sand.
Here comes the motor, a motor suspended over the top of the barrel with a long enough shaft and a propeller at the end would be lowered into the barrel water turning clockwise creating in essense a hole/vortex turning fast enough so that the sand does not have a chance to settle around the prop thus cuasing the motor to stop and jam. Once the shaft is almost at the bottom it would be stopped momentarily and begin turning counter clockwise at near to maximum speed to now begin keeping the sand suspended / fluidized, again not allowing the sand to settle around it.
Where does the variable speed come in, important question you may ask. When sand is kept fluidized it must be kept at a certain height but over the course of time the sand gets heavy becuase it is dirty so over the course of time you need more power e.g. revolutions to keep it suspended. In the end you would ditch the sand and replace new and start over again thus using less revolutions to keep it suspended so that is where the variable speed comes in.
In theory you can go full speed, clockwise while boring down, and only need the variable speed in reverse if that helps.
Now long term big picture, imagine this concept over a tank with at least 500-1000 gallons of water with about 1/3 the tank with settled sand in it. Here we would use multiple suspended motors and props with no one motor doing all the work. So long term we are looking at bigger motor, three-phase, and almost forgot an automatic shutoff in case of jam.
We have other challenges later like how do we raise the prop out if the power stops all of sudden and sand has settled around the prop but for the proof of concept that is what we need.
Budget for POC I would say aroun $250 but flexible.
Horespower I could not say but I am thinking at least 1/4.
Please ask more questions and I would be happy to get back to you. Sorry for the short lesson on bio-filtration but big picture helps.
Gil
Answer Gil,
This is one of the top ten questions I have ever dealt with, well written, well thought out, and very easy to understand your ideas, nice job of writing, most can't get their addresses across.
Not the people on here but in business in general.
So we are making a sand filter, and instead of a steady state media filter, where the water pressure forces the water through the cleaning media, you want to bore down, at x rpm, x torque, stop, reverse, energize, and then vertically remove the shaft upwards, then start over? How many times per hour would you guess this operation to occur?
A swimming pool filter is not fine enough for your end product, [enough removal of water contaminates? How about diatomaceous earth? I am referring to the cleanliness goal.
OK first, a 55 gallon drum is 4 foot tall. The shaft has to be 3 foot something long, to get from motor shaft, or IT is the motor shaft, and then you have an impeller of unknown weight, shape, size, material on the end.
2500 RPM< I don't know where that came into your formula, could be it takes that many turns to expose the media to the dirty water to pick up the majority of contaminates.
This becomes a mechanical issue, of balance, shaft rigidity or flexibility, the potential for bending of the shaft or shaft runout, where at 2500 RPM vibration becomes a huge issue.
Next the connection of the impeller to the shaft, most [pumps] run in one direction or the other, are threaded and run in the direction in which the impeller internal threads tighten against rotation, for an experiment you could weld it to a shaft, but then the entire shaft, weld build up, and impeller requires dynamic balancing as a unit, not a matter of a separate balanced shaft, separate balanced impeller [done on a mandrel] and then swap out when vibration occurs, as it will, because no matter what the coating or material the sand will erode the impeller, and not evenly.
I loved the lesson so please fell free, it is a pleasure to read someone who can write so well.
Now here are some ideas, and then you will need to clarify more, as understand sand filters, and agitators, but this is different.
Reversing, variable speed, variable torque can be accomplished with a single unit, a variable frequency drive, that either takes 110 AC from the wall and converts to three phase, so you can use a three phase motor [as small as 1/4 HP] highly recommend you consider that.
The device will include overload settings, timed reversal, manual reversal, timed speed change, manual speed change, inputs [to the drive] of many types: temperature, current [clogged impeller creates a higher current, drive sees the higher current, either shuts down or reverses, many options] to signal the drive to do whatever you want, either on the keypad of the unit or remotely.
A 1/4 HP drive would run about your entire budget. Then you need motor and shaft and impeller, barrel, sand, balance labor, so on.
You WANT THREE PHASE for even the experiment, single phase will be a huge pain in the butt, three phase motors are cheaper, more durable in reversing, standard sized so on.
Next the motor or some part of the vertical drive will need a bearing or way to hold the vertical thrust, [weight of impeller and any force created by the impeller either up or down, so the motor might need a thrust bearing on the top or bottom]. A standard conrad motor bearing has little axial thrust capacity.
Now when the shaft is lowered in the barrel, how do you see that happening? By hand? Does it need to be inserted exactly in the center of the barrel, does the impeller and the distance to the barrel walls have any effect on what you are doing like a pump? The clearance in a pump volute is critical, and determines many properties or pumping.
'
But I think you are stirring more than pumping, do you have an impeller design?
As far as power loss no big deal, at 1/4 HP you could use a computer UPS for a short time and later on, if you got bigger, back up generators or larger battery ups will take care of all that.
To recap, you want three phase! You want a frequency drive/inverter that takes 110 single phase wall power and converts it to 230 three phase.
Then you want to take advantage of all the choices of inputs to the drive for all of the above, like stuck impeller and the sensing of the drive that says STOP TOO MUCH CURRENT< SHUT DOWN OR REVERSE.
Next is balance, you need a flex coupling from motor to shaft, and then some kind of way to attach the impeller to the bottom, maybe a short shaft to impeller and then another flex coupling.
A flex coupling is one that has a rubber boot in the middle and has some forgiveness to runout and lowers the overall unbalance created by mis-alignment, as opposed to making all this rigid.
How do you see the motor attached at the top? Bolted to the face of the motor with either internal threads in the motor face, or bolting through flanged holes to the lid of the barrel?
Again, does it need to go straight down or can it go in at an angle and then energize for the experimental part of this?
Again a 1/4 HP motor [and I have no way to know the required HP for sand in a barrel] is a guess at this point.
Do you have like a sketch of where the impeller goes, wall clearance, have you already put all that together?
Another idea:
Put your shaft in the barrel, then chain drive, or belt drive from a motor on a stand next to the barrel, the up and down picks stand and shaft from a small hoist or lifting device of some nature.
Look for ways in impeller design to keep the operating speed as low as possible, the lower the speed the less the maintenance.
Of all the devices and functions I mentioned, from motor, to balance, to drive, to alignment, I can do all these and more in my shops, including fabrication of the impeller, fabrication of the shafts, all you would ever need.
Look to maybe a 30 gallon tank, for the prototype if possible, smaller is cheaper.
Look over my response and let me know where I missed out on the concept. Also I do not steal intellectual property, so it would be better if you would write me at service@emrrepair.com.
We can talk, exchange phone numbers, if needed and keep this from being too public.
Great idea, I think you can make this work at least the stirring portion, the filtration is your expertise but I have worked on filtration systems before so it is not out of my understanding.
Write me at service@emrrepair.com just put in something like biofilter design or from Gil filter system in the subject line and I will know.
