recommended DC motor

[lpm-dun]

I am looking for a recommendation on the proper DC motor to purchase for a custom project.

My project involves vortexing water using an impeller, which resides in a 1.5" OD stainless shaft residing in sealed bearings - not a whole lot of resistance, easily turned by hand. I need to spin this shaft as high as 3000 rpm. I will install a motor controller to adjust the speed, looking to experiment between 1000 and 3000 rpm. I am using homemade pulleys and a v-belt for the drive mechanism.

I currently have a 1/2 HP, 12v DC motor with running 40 running amps. This motor was a freebie, not my first choice. I am having a hard time working the right power supply to run this motor (needs high starting amps) - before I go too far down this road, I'm wondering if it's better to choose a more suitable motor. I suspect 1/2 HP is overkill - perhaps something smaller won't draw as many amps...maybe can make use of my current power supply, which outputs 30 amps.

Any recommendations as to an "educated guess" for the proper 12v DC motor that can spin this shaft/impeller up to 3k rpm would be a much appreciated.

 

[itsmoked]

Use the smallest 3450rpm three phase motor you can find on fleabay then get the smallest VFD you can find that runs on 120Vac single phase but puts out the 240V three phase the motor will need. You'll then have dial-a-speed with lots of information available from the VFD. Torque, power, current, speed, etc.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

An impeller on a 1.5" shaft turning 3000 rpm in a liquid could easily consume several horsepower.

What is it you are trying to do. Will a kitchen blender not work?

 

[waross]

Permanent magnet DC motor characteristics, (or back to basics).
The torque of the motor is proportional to the current.
The speed of the motor is proportional to the voltage.
Interaction:
As a load is applied to the motor, the speed drops slightly.
As the speed drops, the current increases so as to develop the increased torque demanded by the load.
In an efficient motor there will be only a few percent drop in speed between no load and full load.

Starting: The voltage should be ramped up.
In the old days, DC motors of any appreciable size were never started DOL.
They were started with current limiting resisters that were cut out in steps as the motor accelerated.

With a proper starting voltage ramp and no load, your motor should be able to be started and run up to 3000 RPM with only a few Amps.

WAG: If the starting current is too high then you are either not starting with a low voltage and ramping the voltage up, or you are ramping the voltage up too aggressively.

30 Power supply: If your load/torque curve is anything like a centrifugal pump curve, than at 30 Amps you should be close to the RPM developed at 40 Amps.

Two quick guesses;
1. Your motor may be too small.
2. The motor may be defective. (Why did you get it for nothing?)

Bill
--------------------
"Why not the best?"
Jimmy Carter