×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Motor for 75000 RPM

Motor for 75000 RPM

Motor for 75000 RPM

(OP)
Dear colleagues,

We have designed compressor for 75000 RPM and 1,5kW, but now have difficult time finding motor supplier.

Please, can you suggest high speed motor manufacturer.

Thank you in advance.

RE: Motor for 75000 RPM

Regular motor and a step-up planetary gearbox. You are nearing automotive centrifugal-supercharger specifications, and that's how they do it.

(Was this whole project not thought through before committing to the design?)

RE: Motor for 75000 RPM

If trying to go with AC, you have a problem. N = 120f/P where N = Synchronous speed, f = frequency, P = number of poles. So since you can't have fewer than 2 poles, 75,000 = 120f/2, so f = 1250Hz. You can get VFDs that will put out 1000Hz, but I've never seen one that goes up to 1250Hz.

That said, I have run across a turbo blower mfr that claims they run their blower at 1250Hz, and in looking at their brochure, the photo of the VFD inside of the box looks to be a Vacon product.
http://www.hsiblowers.com/downloads/High-Speed-Tur...

I looked at Vacon's spec sheets and they don't list an output frequency higher than 320Hz, but it may be a special version that they build for this OEM. You might try to call them and see if they will share that info with you, but if you are going to be competing with them, don't count on it.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: Motor for 75000 RPM

Hello,
Are you sure its 75000 rpm and not 7500 rpm.If it's 7500 rpm you can use a VFD and double the frequency and size the motor within it field weakening range.

RE: Motor for 75000 RPM

(OP)
yes, I am sure, we need 75000 RPM, but it is very hard to find, even with gearbox increaser.

RE: Motor for 75000 RPM

I'm no expert on compressors so I'll risk the appearance of an ignorant moron with my response. ponder At 75,000 RPM I would think you would have bigger problems than finding a suitable motor & drive. It seems to me your primary concerns would be bearings and how to keep them cool enough so that they don't expand and seize, then how to design & fabricate the impeller blades etc. so that the centrifugal force doesn't turn them into shrapnel because of fatigue failure.

75K RPM will produce a prodigious amount of rotational inertia. I've worked at two places in my career in which a large process compressor and a large process vacuum pump both were spun at much less speed (range of 10,000 to 15,000 RPM), failed due to mechanical issues, and the workday became very...exciting.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

RE: Motor for 75000 RPM

Automotive centrifugal superchargers are in that RPM range and that power-demand range. The one that's in a vehicle that I own (a Kawasaki H2) uses a planetary speed-increaser with an 8:1 ratio, and the entire drive mechanism for it is inside the crankcase so it is flooded with ample lubrication. Here's an aftermarket one intended to be driven by an accessory belt and which contains its own integral oil supply: https://www.procharger.com/centrifugal-supercharge...

RE: Motor for 75000 RPM

jraef, just for reference, we have hi speed nitrogen compressors running at 50krpm in 30hp range, 24/7, at some petro plants around the USA with our 3000hz max output Refu vector drives (refu.com). these use magnetic levitation bearings.

we also routinely sold many 3000 hz output v/hz drives during the great USA machine tool market in the 70's thru about 2000 - mostly for high speed grinders. We seldom need over about about 1666hz anymore today, but Spindel (aka old Volkmann) still will sell you a very high performance 3000hz drive from 1-300hp today (spindel.com), from stock on most.

As you know, we can no longer supply over, IIRC, 400hz max output for sale outside the USA without ITAR government permission. Those less than friendly countries want them real bad for making nuclear bomb stuff.

So they do exist.

www.KilroyWasHere<dot>com

RE: Motor for 75000 RPM

I seem to recall the turbo-expander in an Oxygen plant I worked on spun at 30.000 revs

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources