Low Speed High Torque Motors

[HiTorq]

We are attempting to source low-speed high-torque VFD drives in the 200 to 750 HP range and appreciate hearing from fellow members own experiences.

How manufactures such a motor and control system?

Any advise?

Thanks,
Don West

 

[waross]

What is your definition of "Low speed"?
900 RPM, 600 RPM, 360 RPM, ??
yours

 

[HiTorq]

~10 RPM is the target speed.

 

[waross]

The cheapest induction motors are usually 1800 RPM synchronous speed. The size and price is usually inversly proportional to the speed.
If you find that you have to use a gearbox it may be economical to go all the way to 1800 RPM.
A motor of a given frame size will usually generate the same torque regardless of the speed it is wound for.
If you peruse the frame size tables you will find that a frame that is used for 10 HP at 1200 RPM is also used for 15 HP at 1800 RPM and 30 HP at 3600 RPM. There are some exceptions but the relationship is pretty close.
Following that ratio, a 10 RPM motor may be 180 times as large as a 1800 RPM motor of the same Horsepower.
Or, your 750 HP motor at 10 RPM is about the same size as a 135000 Horspower motor at 1800 RPM. I may be off a few hundred percent at these low speeds but your motor will still be quite large and proportionately expensive.
yours

 

[Warpspeed]

Surely you would be looking at a geared "normal" speed motor and VFD combination, rather than a motor that actually runs at 10 Rpm ?

750Hp at 10 Rpm is 394,000 Ft/lb requiring a rather enormous gearbox.

 

[HiTorq]

Thanks for your feedback. Very informative!

 

[jraef]

Well, I think you also must define "high torque" here as well. With a properly designed colling system and a very good quality Sensorless Vector Drive, you can get FULL torque out of any motor at 10RPM, but how high is high? That's full torque, not full HP obviously. If you need 750HP at 10RPM, then a gearbox is the only way to go.

HiTorq, maybe if you described your needs in a little more detail we can direct you on a path to further enlightenment.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[PNachtwey]

"then a gearbox is the only way to go."
No, many hydraulic motors do not need gear boxes.

 

[jraef]

OK, given, but this isn't the "Hydraulic Motor" forum.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[DickDV]

Rather than express your application in hp, it would be better and much clearer to express it in rpm and torque. That way, a number of alternatives can be analysed rather than guessing how you want to use the hp.

Can you do that for us?

 

[aolalde]

Electric, Hydraulic or whatever type of motor , to produce 750 HP at 10 rpm the torque is 393,900 Lb-ft.
Not only the gearbox but the shaft material and diameter should withstand that torque. A motor 5,000 HP, 8 poles at full load produces only around 30,000 Lb-ft.

 

[itsmoked]

Sounds like he's making a shredder to run Earth thru.

Keith Cress
Flamin Systems, Inc.- <

http://www.flaminsystems.com>

 

[stardelta]

If you want a gearbox capable of handling high output torques these are the people to talk to.

http://smcyclo.com/products/largeindustrial/index.shtml