Single phase motor on 3 phase power

Actually, the sewing machine motor is almost definitely a 1/2-3/4 hp clutch motor, or a 3/4-1hp servo motor. The clutch motors don't really offer fine control, and I don't they've got much torque. I can't comment too much on the servo motors, since my industrial sewing machines all have clutch motors, but I have used the servos a bit, and the control range is much finer, but I still doubt the power would be suitable.

Brian Ayres said:
It's almost surely a DC motor. Model trains, slot cars, and lots of other equipment run on DC for variable speed.....


Medicevans... If you buy the single phase motor, then you will need step pulley's like on a KMG. Go to Beaumonts site and price out the pulleys, pillow blocks etc, and you'll see you're not saving much vs getting a 3ph motor with a VFD.
Maybe look at the Vacon or TECO VFD drives to go with a 3Ph motor.... The "standard" is a KBAC27D, but some people use other VFD's with success....

Sam's illustration above helps....

This is what I did.... I bought a KBAC27D VFD, a 3ph 1.5hp motor for my GIB. The cost for the VFD was $400ish. But here's the pay off.
I just bought another 3ph motor off eBay for my disc grinder, now I have variable speed to two machines for the cost of a single VFD and some switches. I plan on adding one more disc down the road to run off the same VFD.

If you did by that motor, you can add a 6" drive wheel and use as is. But it'll be single speed.....

Also, I assume you are looking at 56C motor frames, with TENV or TEFC housing?
Click to expand...
 
Brian Ayres said:
Won't work.

I found a 2hp 3ph 1800 rpm TEFC with foot for $180 free shipping.
Is that "cheap" or expensive to you?
Click to expand...

Well, the 1.5 hp 3ph 3600 rpm TEFC for $78 shipped I found is a steal. $180 I about right, and is better than the $200 2hp 3ph 3600 rpm TEFC I had previously decided on.

I just saw the $78 1.5 hp and thought "wow, if 1.5 hp would be enough, that's a heck of a deal." The $78 dollar motor is an elektrimax as well, which Wayne Coe says are good motors.

If you want to email me the info on that motor Brian, go ahead. Thanks for finding it for me.
 
Fellhoelter said:
That's what the VFD does, turns your single phase into 3 phase, allowing you to vary the frequency, thus the RPM.

Must have a 3 phase motor.
Click to expand...

Just a slight correction:
A VFD changes the frequency from 60 Hertz ( single phase or three phase) into variable frequency (Variable Frequency Drive), usually 10Hz to 100Hz.
There are single to 3 phase and 3 phase to 3 phase. You are correct that the output is almost always 3 phase.

Actually there are single phase to single phase VFD units, but you don't want to go there.

Also, not all 3 phase motors are the same. Some are 3600 RPM, and not as suitable as 1750 RPM units. The best motors for speed control are marked "Controllable". Most 3 phase motors will work OK for grinders.
 
Thanks Stacy.

For better clarity, I should have said
That's what the VFD's we use do, turn your single phase into 3 phase, AND allow you to vary the frequency, thus the RPM.

Especially since their primary purpose is right in their name, Variable Frequency Drive...

I have a couple of 3 phase to 3 phase VFD's around from the days when I used to build automation machinery.
One day, they will be useful.
 
I e-mailed you the link to where I got my new 1.5hp motor. It arrived today. I'll have it running tomorrow.
 
Yes, Fellhoelter, I have a few 3-to-3 Phase units I have picked up for as low as $10-20. I may put a large phase converted in the shop eventually, and wire the work area for 3 phase. Then I can use the much cheaper and larger capacity 3-to-3 units.
 
bladsmth said:
Actually there are single phase to single phase VFD units, but you don't want to go there.
Click to expand...

Could you elaborate on this Stacy? What's the downside or operational problems of the single phase to single phase VFD unit? I'm sure I'm not the only one who's curious about this.

Randy
 
bladsmth said:
Yes, Fellhoelter, I have a few 3-to-3 Phase units I have picked up for as low as $10-20. I may put a large phase converter in the shop eventually, and wire the work area for 3 phase. Then I can use the much cheaper and larger capacity 3-to-3 units.
Click to expand...
Darn it, I have a large rotary converter.
I don't know why I haven't just run a 3 phase line into the grinding room to use those 3p - 3p VFD's that are gathering dust.
 
Brian - And the light suddenly goes on !!!!!

Randy,
They are pretty expensive, and they don't run just any motor. The range isn't what we want in a grinder. I haven't used one, but from what i understand, they are really only for smaller motors and top out at around 1HP.
Most single phase motors will work between 45Hz and 70Hz, but there are tradeoffs in power and overheating. The motors for single phase to single speed control are either DC or universal type motors.
 
bladsmth said:
Brian - And the light suddenly goes on !!!!!

Randy,
They are pretty expensive, and they don't run just any motor. The range isn't what we want in a grinder. I haven't used one, but from what i understand, they are really only for smaller motors and top out at around 1HP.
Most single phase motors will work between 45Hz and 70Hz, but there are tradeoffs in power and overheating. The motors for single phase to single speed control are either DC or universal type motors.
Click to expand...

Thanks Stacy.

Randy
 
VFD's are cheaper in respect to initial cost, when compared to step pulley's. That is correct.

However, protecting, maintaining, and repairing your VFD in a metal working shop does not weigh out the same way when compared against Step pulley's and their mantanence and life cycle costs in a metal working shop.
 
bladsmth said:
Yes, Fellhoelter, I have a few 3-to-3 Phase units I have picked up for as low as $10-20. I may put a large phase converted in the shop eventually, and wire the work area for 3 phase. Then I can use the much cheaper and larger capacity 3-to-3 units.
Click to expand...

Rather than a phase converter, you might consider a motor generator set. Running a single phase motor on metered power to spin up a 3 phase generator winding to a 3-phase panel supporting your equipment. You would gain a big reduction in Electric oven operation costs too.

That will probably be the dirrection I take my shop equipment I am building up. I am checking out Marine service engine generators right now, it seems they will provide a ton of amperage to work with. There is no way in hell I would run an electric oven in California on a metered electric line.
 
ron_m80 said:
Rather than a phase converter, you might consider a motor generator set. Running a single phase motor on metered power to spin up a 3 phase generator winding to a 3-phase panel supporting your equipment. You would gain a big reduction in Electric oven operation costs too.
Click to expand...

Correct me if I'm wrong, but I thought this is pretty much what a rotary phase converter is?
 
ron_m80 said:
VFD's are cheaper in respect to initial cost, when compared to step pulley's. That is correct.

However, protecting, maintaining, and repairing your VFD in a metal working shop does not weigh out the same way when compared against Step pulley's and their mantanence and life cycle costs in a metal working shop.
Click to expand...

That's an interesting way to look at it. I'd be interested to hear thoughts on this opinion.
 
actually most industrial servo motors with variable speed control are very powerful, if you can get your hands on one for a good price i would snag it, but be careful because some of them require really expensive "drives" to run them and input from a programmable logic controller to control them, now i have personally wired them directly to 3 phase 480v and they run fine, just no speed control, so maybe a vfd would work fine in place of the drives???
 
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