Any 3 phase electric guys on here?

I have a 3 phase mill that I am trying to run on a rotary phase converter. The books that I have read on the material makes it about as clear as mud, but I will lay out what I have. I have a line running from my breaker panel to a seperate individual breaker box. I have a 50 amp 220 breaker in that panel, and have it checked by a licensed electrician. From that breaker, I ran to a static phase converter. From the static phase converter, I start and run a 5 hp, 3 phase motor. I have my 3/4 hp mill hooked to the 220 line and I ran the other leg to the uncharged leg on the 5 hp motor, with the explanation of my book saying that would be the "generated" third leg.

My mill will sit there and free spin all afternoon without missing a beat. But when I make a cut, no matter how small or brief the tool is in the material, then it is like I started a countdown timer, and after several minutes, my breaker pops off. It does not shut off immediately, and it doesn't shut off while I am in a cut. I cannot figure out what I am missing.

I have had licensed electricians out here, who understand 3 phase, but have not toyed with phase converters. And having 3 phase run to my garage is absolutely cost prohibitive. Does anyone here understand it better, or know of someone, preferably close, or someone I can talk to by phone about it. It is really cutting into my productivity...I have the mill for the hobby, and I am not a machinist, so it is actually cutting into my learning time...Thanks if you can help...

 

I am interested in the answers to your questions. Subscribed!


Ray

 

Sounds like a resistance problem... have youchecked the brushes and glaze on armature of the mill motor? ... three phase is greek to me!

 

I would ditch the static converter and start the 5 hp motor with a "pony motor". Your pony motor wont need to be more than 1/4 hp or so.

I am looking for a pdf I saved that will explain more than you will ever need to know about rpcs.

Edit: The links posted below me should get you started, still looking though.

 

3/4 HP motor running off a 5 HP motor should be fine, you want double the size of you load, and you have that with ease....check here...hope it helps....

http://www.arco-electric.com/PDFs/RotoPhaseWiringDiagram11112005.pdf

also a great site....

http://www.metalwebnews.com/howto/phase-converter/phase-converter.html

and;

http://www.phase-a-matic.com/RotaryInstallation.htm

 

Sounds like you need a rotary conveter. The static is reduced to 2/3hp.

 

damn right on the rotory. Ran a 5 hp mill hogging cast iron for years that way.

 

why you rinning a motor
and a static phace converter?

you should only need either one
the 3 phase motor is run on 220 and take 4 wires out of it and should work
usually electricians are lost on thiis conversion stuff

 

not all breakers are perfect.

 

Here is the link for the pdf http://www.practicalmachinist.com/FitchWConverter.pdf

Is your static converter in line at all times? If so the mill and idler motor will both be a load on the static converter. This could be too much draw and whats tripping the breaker.

 

who's converter? I run a converter , on my bridgeport, reid surface grinder, nardini lathe and powermatic sander and a 4 spindle drill press..... never a issue i can idle all at the same time, while pushing one hard.

 

Ok, sorry it took me so long to get back to this, had to help a guy fix his racecar...

I have a static converter to start the 5 hp motor, then using the 5 horspower to act as the rotary to run the mill. I totally am aware of the power loss with static converter, which is why I am trying to use the 5 hp as a rotary in the first place...

Falcon, those links are helpful, I will print them off and study them some more, but the static converter idea is a no go...too much power loss when running the mill from a static converter.

I have considered using a 220 motor to turn the 5hp and just use the 5 hp as the generator, but had a lot of unanswered questions that I could not even find answers to on google. I would love to eliminate the static converter portion of this contraption I have set up now.

 

I've never heard of a static converter used along with a rotary one. I've had a static converter on my 1.5 HP Bridgeport for over 20 years and no problems.

Bob

 

I have a home built rotary converter that my father bought used in 1974 and it is still working well. If however it fails I will purchase a Variable Frequency Drive (VFD) which cost considerably less than a rotary phase and they are commonly found with 230v single phase input and will be 3 phase output to the machines you need to operate.

 

I got a cheap 2hp Variable Frequency Drive on ebay, it has a single phase 220v input and a three phase output, and runs my old 1 hp 3 phase mill just fine.

 

If mine was 1.5 HP, 1/3 loss of power would not bother me either, I have an M head Bridgeport and it only has 3/4 horse, so I cannot afford to lose any power....

 

Squirrel, do those cause reduced power output of the 3 phase motor that is hooked to them, like a static converter does?

 

A good electric motor shop is the place to find help for your phase converter problem.

I've worked on several but it's hard to explain to someone else. Most electricians don't know enough about them.

 

Bear in mind that I don't know squat about 3ph converters.....but one thing that bothers me in my shop...is when I run an cfm-thirsty die grinder and I sit there thinking that I am paying to run a 4 or 5 hp 220 volt motor full time while I grind with a tiny bit for an hour


So, are you are running way too much equipment just to be able to use a miller? A miller should not need the full hp rating, so a $75 converter seems so easy and cheap, as well as taking up no space.

My ancient miller runs on the Anderson? from ebay, $75 converter.

 

not that I know of. It's an electronic device that runs on single phase power, and generates 3 phase power, and you can vary the frequency, so you can vary the speed of the motor. All the hep cats are using them these days.

The wiring and programming is a little bit challenging, especially for these chinese ones that don't have very well translated instructions.

 

Well, if I can't get this rotary thing figured out, I guess I will have to look into one of those...you might have to make a road trip to Ohio to program it for me, my chinese is a little rusty

 

-No. The VFD is one of the best ways to run a 3-phase machine. A 2HP rated VFD can run a 2HP machine at full power all day long.

Just be sure to size the VFd correctly- if you have 220V service, get one that takes 220V single phase in, and gives out whatever the HP rating and voltage your machine needs.

Over and above that, the VFD adds several neat features, like soft start (the motor ramps up and ramps down, so the spindle doesn't "slam on" and make the belts squeak) plus variable speed (you can dial it up and dial it down with just a potentiometer) and even overspeed (bump the spindle speed up another 50% temporarily, when, for example, using very small endmills or drills.)

I've got six machines in the shop I run on individual VFDs. (And, admittedly, four more I run on a rotary.)

Doc.

 

I have built and installed several phase converters. I am curious what your amp draw is. The only thing I am concerned with is the apparent loss of power. I would need name plate data to understand more about your problem.

 

I have a 1 hp motor, and got a 2hp VFD to run it. I did some research on the particular crappy chinese brand I was shopping for, and found that some people had trouble with them if they used them at the rated power, so I stepped up for the extra rating (it only added about 20% to the cost).

 

We use VFD's on a lot of the equipment we build. You can even get one that will input 110V and output 220V three phase for smaller motors. You get full power as long as you keep the frequency at 60 HZ. Raising or lowering the frequency (changing the RPM) will lower the HP as you go below 60hz and lower the torque as you go up if I remember correctly. Check out AutomationDirect.com. They have some reasonably priced ones.

 

I'm using a static converter and an 5hp 3 phase idler motor. It powers my 2hp Cincinatti mill with no problems.

 

VFDs are the most efficient way to control motors but you can introduce transient voltages into the systems. Put the VFDs as close to the machine as possible and you might need to use a line reactor on the input side if you have any computer controlled equipment.

 

You could just get a 110 volt motor for the mill, we have 2 bridgeport mills with 110 volt motors plenty of power.

 

Run a common (white) wire to your mill motor.
Also ground it.
Problem should go away.

Bruce

Works good
Lasts long time

 

Can you send a pic of your setup or maybe at least sketch out your wiring diagram for me? This is exactly what I have, and maybe I can find my problem...