Best 3 phase motor for VFD's

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mrbreezeet1

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I was going to try to scrounge up an old 3 phase motor for my metal lathe, maybe 1/2 HP.
Someone said the new motors are designed for VFD's, and I would be better off buying a new motor.
Is this true, and are all new 3 phase motors designed for VFD's, of just some of them?
Thanks,
Tony
 
I don't know if new motors are "designed" for them.

With any used motor it is a crap shoot. My really old motor from my old Rusnok head was whisper quiet. My newer (used) Baldor motor sings a high pitch (could be the motor, could be some settings I'm working on)

My old SB has a pretty quiet motor, and that us really old!

Bernie
 
Leeson makes decent, affordable motors based on my experience and it's the brand of motor that Matt (from Precision Matthews) recommends when folks convert his equipment. I have 3 of them. The instructions come with a packing slip addendum which mentions minimum frequency of 30 to 60 Hz. I don't know if all new motors are this way but, I do know that much older motors had problems with overheating when run at lower speeds. Motors like this are typically TEFC (Totally Enclosed Fan Cooled). The fan is on the outside and blows air past the cooling fins on the case. At lower RPMs the older motors did not have enough air circulation to cool them.

That said, I have a motor that's probably 60 years old on my surface grinder. It is open cage and it does fine on VFD which I operate at speeds from about 2000 to the rated 3600.


Ray
 
Oh, he says no more than 30 to 60?
I run my wood lathe lower and higher than that, but have not run it for too long at those HZ's. I have run it down at 5 HZ to brush on a finish, lets say.

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Wish l still had the 2 motors I tossed 10 years ago.
One off a delta bandsaw, and 1 off my Oliver wood lathe.
Kept them around for a while, but tossed them when I moved.
 
If you're running at very low RPM and not putting a great strain on the motor, I think you'll be fine. I would not run it down real low and try to drill a hole. In that case, I'd increase RPMs and use the gears to get the torque. The VFD on my lathe is set to only allow operation between 40 to 60 RPM. If I can't get the R's I'm looking for, I switch gears.

I would not consider running a motor at speeds higher than 60 Hz (or whatever the instructions indicate).


Ray



mrbreezeet1 said:
Oh, he says no more than 30 to 60?
I run my wood lathe lower and higher than that, but have not run it for too long at those HZ's. I have run it down at 5 HZ to brush on a finish, lets say.
Click to expand...
 
I got this set-up on my wood lathe. Works off 110 volt, I like that.
Working pretty good, but don't know how the import motor will hold up?
http://dealerselectric.com/item.asp?cID=0&PID=6898

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Did you mean 40-60 HZ?

Ray C said:
If you're running at very low RPM and not putting a great strain on the motor, I think you'll be fine. I would not run it down real low and try to drill a hole. In that case, I'd increase RPMs and use the gears to get the torque. The VFD on my lathe is set to only allow operation between 40 to 60 RPM. If I can't get the R's I'm looking for, I switch gears.

I would not consider running a motor at speeds higher than 60 Hz (or whatever the instructions indicate).


Ray
Click to expand...

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Am thinking about going with the same set-up I have on the wood lathe, 1/2 hp is enough for a 10" logan right?
http://dealerselectric.com/item.asp?cID=0&PID=6898
 
Dealers electric said in there FAQ,
"Most 3 phase motors made today are inverter duty"
No, actually it says,

Q. Do I need a special VFD rated motor?
A. If you already have a motor use it, you can always change it later. Most motors manufactured today are rated for use with a VFD. Some models will allow you a greater range of speed than others. You can always contact us to help with your selection.



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You guys think 1/2hp is enough, or should I get the 3/4hp again.
 
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