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I have a dc 750w 220v motor on my lathe and no electronic speed control. I read somewhere a guy did a modification on the same motor by rewiring the coils of the motor as 3 phase so that he could use a VFD to run it.
There are shops around my location that I can get the mod being made but want to ask for your pinions first. What are the cons and pros of this mod?
Why not use a DC control?
Like a dimmer?
Sorry I am not familiar with inverters/controllers. Can you be a little more specific please? Links or pics would be nice.
No 1 - Is the motor a P.M. or wound field?
But there is no conceivable way I can see modifying a DC motor to an induction motor, which a VFD would require?
As already mentioned, there are many DC speed controllers out there, the principle ones are made by KB or Baldor, and show up on ebay all the time.
Al.
Now that's interesting. I didn't know that there are such nice units for the job. This one seems fine for the job. New Baldor DC Motor Speed Control BC202 CN3000A47 | eBay
The lathe is from a German company but their products are Chinese. I couldn't find much info about the motor of the lathe. I emailed them and request some technical data but they never returned to me. All I know is the motor is a single phase 750kw 220v 50hz.
Did you or are you using one of the DC controllers? Will be there any power drop when I use a DC controller? Say when I work at low speed, will the motor bog under some load? Another question about reversing. Does a DC controllers allow reverse?
Sorry, too much questions here.
This is the motor I have and the connections. I can't even tell if it is AC or DC.
And this the lathe http://www.hirdavatmarketim.com/modu...1_2709_max.jpg
That is a single phase AC induction motor, runs directly off of the AC supply, the best bet is to either fit with a DC motor such as treadmill type and use one of the forementioned controllers, or swap the motor for 3ph and fit a VFD.
Al.
Yes, I've been considering about treadmill motors for a while. They are second hand very cheap.
Thanks for your help Al.
Best, Suat
Yes, Al's right about the motor. I was confused by the dc nomenclature in your first post. And what you have is a .75 kW motor (3/4 of a kiloWatt or about 1 horsepower, in North America) rather than a 750 kW motor, which would be larger than the lathe.
Some questions for you- What exactly do you want to do that the present motor will not allow you to do? Is the present motor working? Why do you want to go the variable speed route? Defining exactly what you must have will make choices clearer.
If you are committed to a variable speed system, no matter what, probably the least expensive option would be a VFD and a used 3phase motor that is the same frame size as the present motor. I suspect you could find a used 3phase motor that size for about the same price as a treadmill motor. Here in the US, a used 3phase 1hp motor sells for $25 or so. Usually they need $30 worth of bearings and an hour or so to replace them then are good for another 30 years. Prices may be different where you are.
If you go the treadmill motor route, be prepared to spend a lot of time on the mechanical part of the job. They're not very well enclosed and will need some protection from dust, oil, grease, metal chips, etc and also will need mounting plates, pulley adaption and perhaps a proper electrical connection junction box.
I would seriously consider using the present motor as is. Additional electronics add cost and complexity and decrease reliability.
Neil