36 pole induction motor
36 pole induction motor
(OP)
Hi There,
I'm in the process of trying to design a 36 pole induction motor for one of our test beds in the factory. It'll be used to test a range of winches that we manufacture and by controlling this motor through a VSD we can perform certain tests without the primary gear box that gets fitted to the completed unit.
I've looked on the web at the various motor manufacturers - a motor of this size (55kW)does not exist as far as I can see, hence my efforts to design a fit for purpose motor.
Despite my best efforts, all I can achieve is a 25kW design, that runs, but with a terrible power factor (copper losses and a huge differential reaction are killing the machine).
My question (eventually) is this: is this a viable proposition in motor design? Should I be looking at a different type of motor (such as a brushless DC or similar)?
Has anybody had any experience with a motor of this size?
Best Regards
I'm in the process of trying to design a 36 pole induction motor for one of our test beds in the factory. It'll be used to test a range of winches that we manufacture and by controlling this motor through a VSD we can perform certain tests without the primary gear box that gets fitted to the completed unit.
I've looked on the web at the various motor manufacturers - a motor of this size (55kW)does not exist as far as I can see, hence my efforts to design a fit for purpose motor.
Despite my best efforts, all I can achieve is a 25kW design, that runs, but with a terrible power factor (copper losses and a huge differential reaction are killing the machine).
My question (eventually) is this: is this a viable proposition in motor design? Should I be looking at a different type of motor (such as a brushless DC or similar)?
Has anybody had any experience with a motor of this size?
Best Regards





RE: 36 pole induction motor
I have seen 18-pole motors once upon a time. Must have been 30+ years ago. If this is for a test bench, I would try and find an old low-speed DC motor - or get one rewound. It should be possible to wind an armature with many turns and thin wire so that you get the desired speed.
ABB has a new range of DC motors and they have no standard. "Everything special" so I guess they would be prepared to make one that fits your needs.
Do not fear brushes and commutator. It is a mature technology and I still see lots of DC machines around. They are even being installed in new applications.
Another way to get a low speed is to use a hydraulic drive. Although 55 kW seems to be rather low for such a drive.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 36 pole induction motor
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If we learn from our mistakes I'm getting a great education!
RE: 36 pole induction motor
When you drop the speed of a motor, the torque often stays the same and the horsepower drops. A simple evaluation indicates that a 36 pole machine will have about 1/9th the HP of a 4 pole machine in the same frame. A rigorous solution will probably yield similar results.
You can probably find an off the shelf motor with an integral gearbox to serve your purpose for much less than the cost of a 36 pole machine. If you have to design and build it yourself, the savings will be even greater. The higher speed motor with a gear box will also be lighter and easier to handle than a 36 pole monster.
Bill
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"Why not the best?"
Jimmy Carter
RE: 36 pole induction motor
I have seen induction motors around 24 poles or so. They were used for low speed pumps and ran somewhere around 300rpm. FYI, any induction motor with that many poles will have a low power factor and efficiency. Those motors drew about 50% more current at full load compared to a 1800rpm motor of the same hp.
No manufacturer will list such a motor on their website. You are talking about a custom design. If you were looking at a larger motor I'd suggest using a brush-type synchronous or possibly using a brush type synchronous design with a squirrel cage rotor.
RE: 36 pole induction motor
RE: 36 pole induction motor
andymel; Maybe you could better describe your ultimate use/rational?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 36 pole induction motor
He says that "It'll be used to test a range of winches that we manufacture and by controlling this motor through a VSD we can perform certain tests without the primary gear box that gets fitted to the completed unit"
That is a perfectly valid reason to me. And it would surprise me a lot if he hadn't given use of a gearbox some consideration. Especially since he mentions them in his OP. What is really difficult to understand is that andymel actually seems to have tried a 36 homebrew pole motor. That's amazing.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 36 pole induction motor
http://www.etel.ch/Torque_Motors
RE: 36 pole induction motor
RE: 36 pole induction motor
It was a custom-built, vertical motor by GE made some 40 years back. The core size of the motor was 250 mm long x 675 mm dia. Your size could be around 500 mm x 700 mm. Not that big.
* I would go green if only I were not yellow *
RE: 36 pole induction motor
Edison123, I used an IEC 355 frame as the basis for lamination design as this also ties in nicely with my space factor (700mm od x 500mm lg is in my current design). A copper barred rotor with laser cut stator/ rotor lams makes for a very simple manufacturing process.
A gearbox arrangement may be my only out at this stage. Thanks guys,for all the comments on this post, it confirms my earlier fears that I might be flogging a dead horse with this project. However, the fact that somebody has seen one (cheers Edison123) gives me some hope. Back to the drawing board!
Best Regards
RE: 36 pole induction motor
RE: 36 pole induction motor
Bill
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"Why not the best?"
Jimmy Carter
RE: 36 pole induction motor
Thanks. As you know, the pf will be poor due to the high poles. In my case, the no-load current was 50% / 80% for 20 / 40 poles. And you cannot use capacitors with VFD's.
The rotor was aluminum die-cast.
If you are doing the 36 pole design from scratch, avoid stator/rotor slot combination where the difference between slots is equal to 1, 2, 34, 35, 36, 37, 38, 72, 108 & 180.
Best wishes for your interesting & courageous (!!!) project. Keep us posted with the results.
* I would go green if only I were not yellow *
RE: 36 pole induction motor
for low speed water driven AC dynamos? Horizontal Pelton
water wheel generators.
There might be quite a market in small stream hydro power
plants with multipole generators and indeed, with the VFD
driving it, might prove an alternative to rolling your own?
Hey, bear with me. I'm just a computer (confuser) guy. Just
a thought.
Cheers,
Rich S.
RE: 36 pole induction motor
not in your requirements, but check the size/wieght to horsepower ratio.