Another Grinder Motor Question...

B

Bobbybirds

Joined
Aug 17, 2012
Messages
180
Hey all,

The little 1x42 is getting a bit limiting as I am progressing so I have been saving my pennies and am working towards buying a 2x72. Here in Canada our options are much more limited than for you folks, our neighbours to the south, as most of the grinder companies in the states will not ship outside the lower 48, but one of our local suppliers has picked up the KMG grinders, but they do not sell them with motors.

I am currently running 220 out to my shop from my house. I have the wire buried (in conduit) and am just waiting for my electrician to come install the new panel. In the meantime I am trying to iron out a setup that will work for me. I know I want a 2hp and enclosed is the way to go, and I want variable speed without a stepped pulley system..

My question is in regards to the motors themselves. I see many guys will use a 3 phase motor and then use VFD to run it on single phase power. Can a person not get a single phase motor and still be able to run variable speed? All the threads I keep finding usually refer to running 3 phase and VFD if you want variable speed and it seems to me a more expensive proposition but if it is what I have to do, I will do it.

Any recommendations on what is better, or maybe I should say proper?
 
It isn't what you have to do, but you're going to need a variable frequency drive, and they create three phase power, and three phase motors work much better than single phase motors when used with a variable frequency drive, so most folks run 220 single phase to a variable speed drive that creates three phase power and run that to a ~ 2 hp totally enclosed fan cooled (TEFC) three phase motor. The best results come from using an inverter rated motor designed for 10:1, meaning a 1700 RPM motor that is rated to run as low as 170 RPM and generate good power without overheating at low speed. That motor can also be run up to about 5,000 RPM without problem.

Any three phase motor can be run on a VFD, but a motor designed for it works better.
 
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Bobbybirds said:
Hey all,



My question is in regards to the motors themselves. I see many guys will use a 3 phase motor and then use VFD to run it on single phase power. Can a person not get a single phase motor and still be able to run variable speed? All the threads I keep finding usually refer to running 3 phase and VFD if you want variable speed and it seems to me a more expensive proposition but if it is what I have to do, I will do it.

Any recommendations on what is better, or maybe I should say proper?
Click to expand...

How else did you want to do it ?

More expensive than what ?
 
12345678910 said:
How else did you want to do it ?

More expensive than what ?
Click to expand...
Sorry my electrical knowledge is minimal so explaining may not be so clear. I just meant that in my basic understanding I was thinking it seemed to me it would be less expensive if it worked in buying a single phase motor and variable speed controller than having to buy a 3 phase motor and a converter and variable speed. Like I said, my electrical knowledge is greatly lacking.

Forgive me, but you may have to map this out like I just learned English yesterday...

I am going to make myself sound stupid but sometimes you just have to admit when you know nothing so you can learn something.

So is VFD the actual speed controller or is VFD the phase converter or is it a combination of both? Am I basically to understand that I will need a VFD whether or not the motor is single phase or 3 phase? If this is the case are we saying that a 3 phase motor is a better operating option than a single phase?

Nathans description of what I need leads me to believe I should really ideally be considering 3 phase. Is that pretty much the ideal map to follow for set up?

Sorry again for what might be ridiculous questions...

Edit - Here is a link to a 3HP single Phase motor I found that seems reasonably priced, but can I easily adapt a controller to it to make it operate with variable speed? If it is really not up to the job I absolutely will forget about it and move on...

http://www.princessauto.com/en/detail/3-hp-totally-enclosed-fan-cooled-electric-motor/A-p8601668e
 
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That looks about right except for the 3HP part. There is no good way that I know of to make that variable speed without a VFD. IF you get a VFD they go up in price depending on the HP they need to run. A VFD for a 1 HP motor is much cheaper than one that will run a 2 HP, and that one is much cheaper than one needed to run a 3 HP.

This company looks like they will ship to CA. This would be a perfect setup for you. It's the same set up I run on my TW90. The price is not cheap, but it will last you a long time and will give you great speed control and power.
http://www.electricmotorwholesale.com/LEESON-116106/
http://www.electricmotorwholesale.com/9520-KBAC-27D/
 
most folks run 220 single phase to a variable speed drive that creates (variable speed) three phase power and run that to a ~ 2 hp totally enclosed fan cooled (TEFC) three phase motor.

The drive creates the 3 phase power and also controls the frequency of it, which is what controls the motor speed. A three phase motor works better, costs less and will last longer than a single phase motor. There is no reason for you to use a single phase motor. Your single phase power will power the drive which will power the three phase motor. No converter needed. Just be sure to order the correct drive.
 
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