Coyote VSD's 1

[EMSGuy]

We are currently loooking at a new (to me) variable speed drive sytem and I was looking for input -good or bad-.
The drives are Coyote Payback VSD's. I until now have never heard of them and am somewhat skeptical. The application is for AHU's and we are currently using Danfoss VLT 6000's. Our controls system is Metasys Extended Architecture utilizing JCI NAE's and all applicable unitarty controllers. The nice thing about the Danfoss drives is they are totally N2 mappable/ compatible. I can input signal into the Coyote but not really control it.
Are these drives reliable?
Any help or info would be much appreciated..

 

[jraef]

They are NOT Variable Frequency Drives, they are essentially magnetic clutches. That is the reason why you cannot get any feedback information from the drive itself, it is not in control of the electrical power directly or even monitoring it.

Much has been discussed in this forum regarding the real "energy savings" of using a magnetic clutch vs a VFD on an AC motor. There is some energy savings, and it is true that you don't have the harmonics issues that you will with VFDs. On the other hand the energy savings are more dramatic with VFDs, and as you have already noticed, interfacing them to building atomation systems is more straight forward. I for one have never heard of "Coyote" before, and their marketing website appears to be geared towards the "smoke-and-mirrors" side of the energy savings neo-industry. Whereas Danfoss is a long established and solid company who will likely be here 10 years from now, with a well established track record of quality products and support. In addition to Danfoss there are a lot of other high quality VFD manufacturers and a lot of people familiar with their operation. I doubt you could say that for magnetic clutch drives at this time. Maybe some day if it really is as good as they profess, but not yet.

For what it is worth, just the name "Coyote" gives me the willies! That is the name given to unscrupulous guides who supposedly help sneak Mexicans across the border and but usually leave them to die in the desert!

"Venditori de oleum-vipera non vigere excordis populi"

 

[ScottyUK]

These things were discussed in fairly recent times on Eng-Tips, though I can't find the thread. It is basically an eddy current coupling as I recall. Not good for high slip applications - they get hot!

Someone had a lot of knowledge of these things - DickDV perhaps? - and posted some good comments. Hopefully he is reading and also recalls the previous thread.



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

 

[DickDV]

I did a quick search for the eddy current clutch threads too and came up empty.

Basically, these devices are 1950's technology and are huge energy-wasting devices. On constant torque loads, the wasted energy is equal to the full-speed load torque times the percent speed turndown so, for example, if full speed load is 50hp and you are running half speed, 25hp is wasted as heat.

On variable torque loads like fans and pumps, the lost energy is not so high because the load torque drops off as a function of the square of the speed. However, the losses are still large and far higher than when a VFD is used.

Worse, an eddy current clutch slips between 2-4 percent at full speed so you have these extra losses even when running wide open.

Bottom line---never a good idea! Eddy current clutches are being replaced in industry by AC drives at a rapid rate. Installing a new one is just plain foolish.

 

[jraef]

As I thought about it some more, I remembered our old friend jbartos frequently providing links to Magnadrive as a speed control solution. I did a Keyword search on that name and came up with a bunch of threads. Here are a couple:
thread237-48822
thread237-73647


"Venditori de oleum-vipera non vigere excordis populi"

 

[thecoyote]

Pacific Northwest Labs, under the Federal Energy Management Program for the U.S. Dept of Energy, recently did a test comparison between the Coyote "PAYBACK" belt drive model, a VFD, and the MagnaDrive. This test was titled "Technology demonstration of Magnetically-Coupled Adjustable Speed Drive Systems"
The results of the 50HP test showed that the Coyote "PAYBACK" drive provided the fastest simple payback based on overall energy savings, installation cost and maintenance. Of all models tested, the VFD tested as the highest efficiency, the MagnaDrive had the lowest efficiency, with the Coyote PAYBACK drive efficiency testing in the middle. If any of you are interested in the test results, just forward your email address to info@payback.com and I will be happy to send you the complete test in pdf or zip form (Approximately 3 meg file).
The New Coyote Easy PAYBACK model was developed and patented as a greatly improved design over earlier eddy current technologies of the past. It is more efficient and has fewer parts than all other magnetic coupled drive designs in the industry. It is used for energy saving speed control of variable torque loads such as fans, pumps and cooling towers as a reliable alternative to VFD's where low maintenance is important, where there are harmonics issues, or when there is concern for parts availability 10 or 20 years down the road. (These drives are flat specified in Hospitals, Airports, Universities and Government Facilities because of these reasons). This particular model is in use in thousands of applications throughout the U.S. and Canada since 1993 and has an excellent track record. Many Airhandler Unit MFG. OEMS now install the Coyote drives directly in their units and forward to the end user on specified jobs. In retrofit applications, a new motor is not required, as a magnetic coupling has no negative effects on the motor.
The drive is simple to control and monitor via standard analog signal connections to any ems system. Since the drive is a magnetic coupling, it is totally isolated from the power source and therefore are no provisions to interface with the motor power. If realtime power monitoring of the motor is required, it would have to be done separately as an option, as this feature is not offered with the standard Coyote system, whereas most VFD's automatically do provide this function.
Regarding most belt drive applications, the Coyote PAYBACK drive is a less costly alternative to the MagnaDrive because it does not require assembly and the Coyote drive is supplied with an integral pulley, (The MagnaDrive would require a third party to devise a jackshaft and pulley arrangement to fit up between the motor and driven equipment). Coyote shaft mounted drives are available in both Belt drive versions and direct coupled versions, as a complete and simple component that mounts directly to the motor shaft and is available in hp ranges from 1/3 hp - to 200 hp. The MagnaDrive technology offers larger HP applications, as I understand, up to 1500 hp.
As a side note, Coyote Electronics, Inc. has been in business for 21 years (since 1983) and to my knowledge none of these Coyotes have been smuggled across the border and none have died in the desert...but as a matter of record, they have indeed replaced many VFD's and other eddy current drives that have died.
I hope this helps to clarify some of your questions. If you need additional information on this technology, go to

http://www.payback.com

and you will find the latest downloads available. If you would be interested in real customer user references that have first-hand experience with all of the above technologies, just send an email to info@payback.com

 

[ScottyUK]

Thecoyote,

If you work for Coyote / Payback, it is good practice and a professional courtesy to disclose this fact. Do you work for them?



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

 

[thecoyote]

Thanks ScottyUK for your question. I did not notice anyone else providing in these threads their name and company affiliation in the text, however I had assumed since I thought I had checked the Signature box, my name would have been included with the posting. It is the first time I have ever responded to this media. Please allow me the professional courtesy of getting up to speed. My name is Dewey Boggs and I am the President of Coyote Electronics, Inc. I hope that the information I provided was helpful and informative, and if anyone reading this has any questions about the Magnetic coupled technology discussed here, I would be happy to reply.

 

[ScottyUK]

Thank you for your candid reply: it is nice see that you aren't trying to sell your product by posing as a 'delighted user' but are prepared to nail your colours to the mast.

So far as posts generally are concerned, you can use the 'preview post' button to check how things will look prior to committing them irrevocably. Signatures and the like show up in the preview, so I hope you find it useful.

My own limited experience of the technology your product is based upon is that it can be made very reliable and robust at the expense of being massively constructed, but in applications requiring large speed reduction while maintaining torque they are very lossy and run at very high temperatures. This heat is paid for by the user in the form of his electricity bill. In such applications I suggest that drives employing eddy current technology are a very poor choice from the point of view of improving efficiency. The dreadful efficiency of these things is less pronounced on variable torque loads such as fans, but it is still present.




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

 

[UKpete]

thecoyote, I'm sure nobody thinks you were trying to hide your identity (the handle is a bit of a giveaway). I would agree that there is at least a market niche for your product; there is criticism of the energy losses - if DickDV is correct then in his example of a constant torque load running at well below motor speed there is a very large amount of heat to be dissipated.

On the general question of energy savings, I don't want to step too far out of line but I think it needs to be pointed out every now and again that although we may develop systems that are highly energy efficient, the savings are dwarfed by the amount of energy use that is unnecessary.

 

[thecoyote]

Thanks ScottyUK and UKpete for the good comments. Do not be surprised that I agree with you about the older eddy current drives being constructed "oversized" to handle the torque at reduced speed for constant torque loads because of the obvious reasons you addressed. Also, these older eddy current drives had to be constructed in such a manor because they were typically a footmounted, box type design that required multiple bearing arrangements, and had to serve the industry in the field that governed their application at the time (Pre-VFD).
Unlike these older eddy current drives,the Coyote drives, which are also eddy current drives, are a different animal (pardon the pun). They were developed per customer request as an alternative to existing speed control methods and to fill a specific need for variable torque applications only. A priority was to reduce the size, weight and complexity of the technology in a simple, shaft mounted design and provide a reliable speed control method that could be easily self maintained and could be mounted on existing motors without the concern of causing motor winding failure or power line disturbances. Another priority was to provide a drive with the highest achievable efficiency in a magnetic eddy current coupling. The Coyote drives are the accomplished result, and are second only to vfd's in energy savings in variable torque loads.
As far as I know, there have only been a couple of other styles of shaft mounted eddy current designs introduced in the past (circa 1980's), but they were more complex and more expensive to produce (more parts usually means more problems). At present, the Coyote drives are the only patented, fully self contained, shaft-mounted electromagnetic e.c. drives with a fixed airgap offered for variable torque application.
One of the important questions that EMSGuy asked was "Are these drives reliable?" The short answer may be to ask the very first Coyote user this question. The first 40 plus drives were field installed in 1993 in new Air-handlers as part of the State of Texas Capitol expansion in the main Capitol Rotunda and House of Representatives offices in Austin Texas. Eleven years later, all of these Coyote drives are still operating today 24/7, including the Coyote drive that runs the governor's office: first Ann Richards, then George W. Bush, then Rick Perry. Based on the history so far, I expect these Coyote's should last well beyond a few more hopeful politicians.

Paul "Dewey" Boggs, III
President/CEO
Coyote Electronics, Inc.