MagnaDrives

[7carisfast]

Anyone have any experience with Magnadrives on motors >500HP? Their website is very convincing, but I don't see this technology taking off like I thought it would. Just wondering why.

http://www.magnadrives.com

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[gepman]

There is a brief discussion of the MagnaDrive in the following recent thread:

http://www.eng-tips.com/viewthread.cfm?qid=205555&page=1

starting with my (gepman) post of Dec. 27 @ 14:56.

It is very similar to an eddy current drive except that it doesn't need a current to develop the magnetism which makes it about 2% more efficient.

In order to make it worthwhile using the MagnaDrive the load would have to be a variable torque load and there would have to be a compelling reason NOT to use a VFD.

See the previous posts in the same thread for some of the compelling reasons.

 

[ScottyUK]

Some discussion of eddy current drives in:

thread237-107895

thread237-98040


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If we learn from our mistakes I'm getting a great education!

 

[jraef]

They have their place in the world for sure, but throughput efficiency is their Achilles' heel. I have seen them used in machines called Digesters for the pulp and paper industry, where starting can be a serious problem but variable speed is of no benefit. But if variable speed offers tangible benefits, the Mag-drives lose out to VFDs.

If you do a keyword search on Magnadrive on the Electric Motors and Control forum you will find a number of old threads where they were discussed. A member who has since left Eng-Tips was a big proponent of them and would drop their name at every chance he had.

 

[gepman]

I have attached some papers on Eddy Current efficiency vs. VFD efficiency. Some are a little dated (since you don't see to much regarding Eddy Current drives anymore).

jraef Why don't they use solid state soft starts on the digestors? Too long of start up time?

 

[gepman]

I forgot to mention that the papers that I posted are for fans or other variable torque loads. For constant torque loads the eddy current should not be considered since the loss in efficiency is proportional to the speed (i.e. at 25% speed you waste 75% of full speed power).

Another possible use for these MagnaDrives is as they state, if there are suddent impact loads since the drive will slip since there is no direct physical coupling.