3 Phase rotary converter

[Kbeitz]

I just made my first balanced 3 phase 1Hp. rotary converter today. Works great. I'm happy. Next step is a bigger one. It took some head scratchen to get the wiring right but it worked the first time.

[Kbeitz]

I'm just a little disappointed. I have 20 new 3hp PM 3ph motors that I wanted to use. I see they wont run on just 3 phase electric. They need a digital AC drive to make them work. That was my plan for building these converters. This is the motors I wanted to use. It's the first time I've worked on anything like this. The magnets is in the rotor not the field.



 

[mike_belben]

Is that an encoder on the back?  Servo motors?

[Southside]

What is your plan for the motors?

[Kbeitz]

Is that an encoder on the back?  Servo motors?

Yep...

[Kbeitz]

What is your plan for the motors?

You can never have enough motors. I'm always needing one for something I'm building.

[mike_belben]

Those are a pretty penny.  Put em on ebay and build your bank account back up.  

They look about the right size for bridgeport cnc retrofits.  But servo control is a lot more money and complexity than stepper.  And by now most knee mills out there are too lose to take advantage of the added resolution from a servo.

[pineywoods]

Looks sorta like a heavy duty brushless dc motor, or possibly a stepper motor depending on the encoder. Either case, some serious electronics required. Probably came off some industrial robots.

[Kbeitz]

The only information I have about the motors is .

Motor: 3HP, 220V, 3-phase with inverter for single phase power equipment
Electronic variable-speed spindle control VFD; Power requirement


They came out of Grizzlys wood lathe GO 800.

[mike_belben]

Well originally they probably came out of wang chang china.  

Do they turn smooth or cog a little by hand?   Stepper control is cheap but 3hp servo is $$

[Kbeitz]

Well originally they probably came out of wang chang china.  

Do they turn smooth or cog a little by hand?   Stepper control is cheap but 3hp servo is $$

I really don't think they are ether one. Only 4 wires coming from the motor not counting the encoder. Three hots and a ground. If I chuck one up in my lathe and wire it to another one on the bench it works great as a generator. The rotor has strong magnets on it and there is no brushes anywhere. Hooking up to my new phase converter it jumps all over the table. Hooking up other motors and it's works fine. Could it be 3 phase DC? I have worked on lots of motors but I have never seen anything like this before.

[Don P]

Don't know if you've already got it but the wiring diagram is on pg 53 here;
http://cdn2.grizzly.com/manuals/g0799_m.pdf

Looks like a bunch of control needed.

nice looking rotary, my first attempt I let the magic smoke out in the house and got banned from indoor wiring experiments :D

[Larry]

The GO-0800 is the flagship in Grizzly's wood lathe lineup. It hasn't been out long, so it would be a surprise to come across 20 brand new motors unless they are somehow defective.  I suspect they run just like any other 3 phase motor but have an inverter duty rating.  My understanding of inverter duty is heavier insulation on the windings to withstand more heat, which is caused by the inverter.

Are you trying to run them with your new rpc?  Most converters are sized at 100-200% of the motor they will be running. I wouldn't expect a 1 hp rpc to start a 3 hp motor. 

[mike_belben]

I dunno, its above my paygrade now.  Sounds like 4wire 3 phase for a continuous rotation.  Dont know why theyd have an encoder.  

Make windmills.  

[Southside]

Could the encoder be measuring the RPM the motor is turning at?  A lot of the higher end lathes these days have a digital RPM display.  

[mike_belben]

I really dont know, maybe.  An encoder is an awfully expensive tachometer though.  They generate very high resolution feedback on position to ensure the rotor travelled the precise amount that the controller dictated.  Like way more precise than a stepper, and those have pretty fine resolution when multiplied through a leadscrew's TPI. 


On a lathe, a servo would normally be coupled to ball screws for XY automation.   Not much other need for encoder feedback i can think of. 

[Kbeitz]

The GO-0800 is the flagship in Grizzly's wood lathe lineup. It hasn't been out long, so it would be a surprise to come across 20 brand new motors unless they are somehow defective.  I suspect they run just like any other 3 phase motor but have an inverter duty rating.  My understanding of inverter duty is heavier insulation on the windings to withstand more heat, which is caused by the inverter.

Are you trying to run them with your new rpc?  Most converters are sized at 100-200% of the motor they will be running. I wouldn't expect a 1 hp rpc to start a 3 hp motor.

The encoder was to the measuring the RPM. Before the lathe hit the market it had a problem. It shocked everyone. So all the motors and the controllers was replaced. 100's went to the trash. They took no chance with them. Everything got replaced. The motor did start and run off my phase converter but it jumped around on the bench like I was trying to run a DC motor off AC. This is one of the controllers. I can not duplicate the shock. I only have a few controllers. At the time I got the motors just to make bank mowers with them. I put one on the PTO of the tractor and one on the mowing deck to run the blades. Worked great..

[mike_belben]

I have to see this DC mower.

[Kbeitz]

I have to see this DC mower.

4th picture down from the top of the page....
And if it's DC I would think it would have to be pulsating DC.

[Crusarius]

brushless dc motors are not always for continuous rotation. I have a few on my desk right now that are being used to open and hold butterfly plates in EGR valves. The sensors are for position feedback.

One has 80 degrees of movement the other has 70 degrees.

[petefrom bearswamp]

My ignorance of this stuff makes MEGO.
Bought a converter kit about 17 yrs ago to run my 10HP planer and put it together OK but have now idea how it works,.
I t has several capacitors and the guy sent me a few spares which I haven't needed to date.

[Kbeitz]

My ignorance of this stuff makes MEGO.
Bought a converter kit about 17 yrs ago to run my 10HP planer and put it together OK but have now idea how it works,.
I t has several capacitors and the guy sent me a few spares which I haven't needed to date.

I bet that they are not spares... You need to put an amp gauge on each output leg and see if the amps are the same. Then do the same with a volt meter. All three lines should be within a few volts of each other hot to neutral. The spare capacitors they should be run capacitors used to balance your converter. More or less depending on your motor load that your using. It's trial and error to get it balanced. 12 to 28 mfd per output Hp. There will be to banks of them. So you will need to change both sides when doing this. From the true legs to the what I call the high leg.

[petefrom bearswamp]

Mine is 15 hp motor with 13 capacitors.
Motor is Marathon which I always thought was US but is chinese.
All was within spec when I built it.
As I recall, voltage on convertor leg was about 1 or 2 volts different than line.

[Kbeitz]

Mine is 15 hp motor with 13 capacitors.
Motor is Marathon which I always thought was US but is chinese.
All was within spec when I built it.
As I recall, voltage on convertor leg was about 1 or 2 volts different than line.

You cant get much better than that...

[petefrom bearswamp]

glad to hear that should i check current specs again in case of a failed capacitor?