Low-speed with high torque
Low-speed with high torque
(OP)
Hello, I am new here and don't know much about motors but I hope you could be kind enough to help me find what I look for.
I need a 240V electric motor with 5+ Nm of torque. It will run at 0-180 rpm and I wonder what kind of motor I should use that has that torque no matter what speed it's running at. 5x5x5 inches size or smaller would be nice.
Not sure about what to use for adjusting revs of the motor, preferably something small enough to fit in a hand-held unit.
As you can tell I'm clueless about this stuff which is probably the simplest thing in the world to you guys, but I don't know who else to ask so please bare with me.
A list of what specs the motor I need would be lovely.
Thanks
I need a 240V electric motor with 5+ Nm of torque. It will run at 0-180 rpm and I wonder what kind of motor I should use that has that torque no matter what speed it's running at. 5x5x5 inches size or smaller would be nice.
Not sure about what to use for adjusting revs of the motor, preferably something small enough to fit in a hand-held unit.
As you can tell I'm clueless about this stuff which is probably the simplest thing in the world to you guys, but I don't know who else to ask so please bare with me.
A list of what specs the motor I need would be lovely.
Thanks





RE: Low-speed with high torque
You are going to have a problem with varying the speed of a 100W AC motor.
That puts you below common 3 phase motors and the VFDs that can control their speed.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Low-speed with high torque
RE: Low-speed with high torque
ht
So many motors to choose from there.
RE: Low-speed with high torque
I think anything with Bodine written on it is one solid unit.
The three phase 0641 would certainly provide the twist and speed you need. Then you need a VFD to turn it down since you stated 0 rpm in your original question.
It sure misses the 5" requirement being 11" long.
What are you building?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Low-speed with high torque
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Low-speed with high torque
The motor being 11" is ok, if you say it has enough power then I'll go for one of those.
What is a VFD?
RE: Low-speed with high torque
For speed variation you will for sure need some kind of inverter.
RE: Low-speed with high torque
Juleen; You need to look up VFD or Variable Frequency Drive.
Get educated on the subject if you are contemplating one. Come back with a specific question/s.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Low-speed with high torque
If I understand correctly a DC motor is easier and cheaper to speed control than an AC motor. I thought of two things to do.
A power supply thingy from a computer and then use a 12VDC motor, or wiring a 180VDC with bridge rectifier (25+ amps?)and capaciror (3+ uF?).
I've found lots of nice 110 and 90 motors but since I got 230 in the wall I guess I can't use those.
So to the new question, gentlemen! Would it be a good thing to get one like this
http://www.grainger.com/Grainger/items/6ML58
..and operate it by a simple €10 fully variable fan speed control?
RE: Low-speed with high torque
It depends a lot. First, a €10 fan controller usually is triac based and produces phase controlled AC, which obviously doesn't suit a DC motor. So you need to add a rectifier, which is cheap and easy. But that will cause lots of ripple, which is harmful to the brushes and the collector. So you may need some filtering (smooting) using a fairly big capacitor. And that will (perhaps) overtax the triac since it needs to charge that capacitor 120 or 100 times per second. Probably 100 times, since 230 V usually means 50 Hz.
You simply need to test it in your application to find out what works and what doesn't.
Why do you blush? Trying overunity? Are you? Then you shouldn't only blush - you should be red as a cooked lobster...
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Low-speed with high torque
RE: Low-speed with high torque
"220 VAC Full Wave Rectified" What does that mean, sreid?
You saying I should use a rectifier but no capaciror?
Please excuse the newbie questions, I am doing my best to learn.
I changed my mind about motors, I'm gonna but one of these Leeson. Says they are SCR rated.
http://
I guess the 250rpm would be a better choice than the 165rpm, since the 250's gear ratio is 10?
"These can be speed controlled with phase controlled SCRs"
Could you explain that with words newbie understands? And perhaps show me a link where to find one of those thingies
Juleen
RE: Low-speed with high torque
A DC Motor's speed is determined by the average voltage applied. 220 VAC has +/- 300 volt peaks. If this is "Full Wave Rectified (meaning the negative part of the waveform is flipped to the positive side)", the average voltage is about 180 volts DC. If SCRs are used to do the rectification, you can delay the time that they conduct (phase) and reduce the average voltage the motor sees.
RE: Low-speed with high torque
Just one more thing then I'll leave you alone I promise! How strong rectifier and capacitor would you recommend?
RE: Low-speed with high torque
RE: Low-speed with high torque
RE: Low-speed with high torque
RE: Low-speed with high torque
http://web4.automationdirect.com/adc/Home/Home
RE: Low-speed with high torque
http://www.orientalmotor.com/products/ac-motors/
RE: Low-speed with high torque
I see the requirement for torque and speed but I'm seeing a bunch of possible info missing.
How accurate do you want the speed?
Do you need position control, ie, do you need to know the rotational angle of the shaft?
Do you need to know how much it has rotated?
The solution depends on the answers to these questions too.
RE: Low-speed with high torque
No need for positioning control.
No need to know how much it has rotated.
All I need is a motor that I can control the speed of.
I want one of those Leeson motors I linked and I was thinking of buying one of the Leeson control units just like sreid told me to do. That has to be good!
Anything else I need to get it going?
RE: Low-speed with high torque
RE: Low-speed with high torque
Heres a suggestion, how about a cheap electric drill with speed control. You could replace the trigger potentiometer with a regular one and throw away all the surplus bits. Another good motor to use is a auto screen-wiper motor
Roy
RE: Low-speed with high torque
And a picture! Leeson motor and controller work perfectly!
http:
RE: Low-speed with high torque
My guess, some sort of reciprocating saw
Roy
RE: Low-speed with high torque
Keith Cress
kcress - http://www.flaminsystems.com
RE: Low-speed with high torque
LOL, I'm not going to say what came to mind when I looked at the pic.