A few years ago, a member of this forum seemed to be promoting this product as the end-all / be-all for almost every drive application. He is no longer a member; take that for what its worth.

Seriously though, magnetic clutch drives have their place in the world, especially for starting high inertia loads. But as a continuous VFD they leave something to be desired. While they do reduce harmonics issues, they do so at the cost of much of the energy benefits you can attain using a VFD because the motor still runs at full speed and the load is allowed to slip magnetically. You still gain the energy reduction based on the reduced load of course, but not the added benefit of taking advantage of the affinity laws that you can with actually reducing the motor speed and HP.

Here is a link to a thread which has other links in it for you to see previous discussions we have had in here about this technology. thread237-107895: Coyote VSD's

They were heavily promoted around here for awhile and I know of a few facilities where they were installed for comparison with standard AFD.  We helped with some measurements to compare efficiencies, etc.  

I think the advances in AFD technology over the past few years has pretty much ended the debate.  

The mag drives have some perceived advantages in terms of power quality and for starting of some types of loads, but I think it is destined to remain a small niche market.  

Thank you Jraef and Dpc!

I checked out these old threads,... I found very helpful information, but these threads are old 3-4 years. Do you have any new information? I checked out also Coyote Electronics web site,..

Do you agree with the below?

Variable Frequence Drives (VFD):

Disadvantages:
- Initial Cost;
- Maintenance Skill Set;
- Low Speed Overheating;
- Output Harmonics;
- Induced Harmonics-Distortion and Line Notching.

Advantages:
- Energy Saving;
- Improved Process Control;
- By-Pass Capability;
- Multi-Motor Control;
- Low System Maintenance.


What about these ASD?

Thank you once again!

There is a lengthy report on the end of this link:
http://www1.eere.energy.gov/femp/pdfs/mag_motors.pdf
The summary is very good. It shows the Magnadrive to be pretty poor compared to other technologies.
I am currently investing a lot of my time in determining Life Cycle Costs with VFD's using new technologies and I came across this article a while ago. A lot of work has gone into a very professionally presented document.

Thank you very much Sed2developer!

I am going to read it. It seems to me, looking briefly over this document as an excellent source of information. I agree with you, it has been done on a very professional way and also it has been presented very clear.

The only place I have seen one used was 10 years ago at a paper mill where it was starting a refiner connected to an 4000HP 4160V motor. The user had a severe starting power limitation and used the Magnadrive to couple the load once the motor was brought to full speed unloaded. Ironically, the utility still made them put a soft starter on the unloaded motor, so IMHO they might have been better off with a VFD after all. That Magnadrive was almost the same price as a VFD, about $350,000 so when you added in the cost of the MV soft starter, the total probably exceeded the VFD price. I heard later that the Magnadrive melted the copper off of one of the plates and had to be redesigned in the field to match the application. I don't know who paid for that redesign though, maybe Magnadrive absorbed it.

Disclosure;  I represent a distributor of MagnaDrive.
re jraef comment re a former member;  if it was Gus D'Almaeda,  he unfortunately passed away a few years ago.  He was employed by a large oil sands producer and recognised the potential in certain applications.  The original fixed speed couplings have been around for quite some time and were sold mainly through bearing houses, and there were some inappropriate applications;  perhaps the one referred to by jraef was one of them.  
The adjustable speed drives are more recent.  There are some significant differences to eddy current couplings,  with some significant mechanical benefits regarding misalignment tolerance, vibration reduction,  reliability,  simplicity etc.  The report referred to was accurate for the tested unit,  however the test set up was smaller than the typical drive,  so that some losses were higher than in more typical applications.  In a comparison to VFDs ,  there are other losses that should be taken into consideration,  which make the efficiency of the Magnadrive much more comparable.  However,  in analysis of a project, all factors  and costs should be considered over thhe expected life of the project.  Suffice to say, I have been involved with several projects where the end user is delighted ( his word ).  Are they suitable in all applications ? No, of course not,  but in many situations they are well worth considering.
mac

No, the former member who promoted them here was not who you though macmil. He was a long time member who had a penchant for being argumentative and verbose, bracketing each of his comments with an annoying //  \\. He didn't pass away AFAIK, but was just blocked from posting. I was just teasing when I implied he was gone because of promoting a specific product.

Quote (jraef):

bracketing each of his comments with an annoying //  \\. He didn't pass away AFAIK, but was just blocked from posting.

So that's what happened.  Somehow I don't miss him one bit.  I remember having to form questions is such a manner as to say that I had already considered (or was unwilling to consider) all the things he would suggest no matter what the issue.  Unfortunately, too many people thought he knew what he was talking about and he still has the seconded highest number of stars on this forum.

Whoops, I was thinking Power Engineering Forum, where he has the second highest number of stars, this forum he is only number three and numbers one and two are still active.

When ever there is a difference between the synchronous speed and the "output" speed, there are slip losses. The power is equal to the torque times the speed differential. Therefore, if you have a load slowed down by a magnetic or hydraulic means from a motor at full speed, there will be losses in the coupling. If the load operates at half speed, then the load power will be 50% times the torque, and the slip losses will be 50% times the torque, so the slip losses will equal the load power, both of which will be half of the input power.
With a VSD, the slip is only the slip in the induction motor, so the slip losses are a small percentage of the input input power, hence higher efficiency.

Best regards,

Mark Empson
http://www.lmphotonics.com

Irrelevant to the OP.

What is AFAIK ? (My guess, As far as I know ?.)

I am so poor in sms lingo that my teen-aged daughter told me that sms means SHORT message service, dad. That apparently means using a language which I never will master. (Thank God).

*Nothing exists except atoms and empty space; everything else is just an opinion*

Edison,

You guessed correctly.
 

----------------------------------
  Sometimes I only open my mouth to swap feet...