As most know I got a new 3 phase lathe I have hooked it to my original rotoy phase converter with a new 10hp motor and it kept dropping the generated leg to low so today I score a brand new 15 hp which shoould have started the lathe without a problem, Wrong I am still dropping the generated leg to low so i get a fault on the Fanuc controler. SOooo any suggestions as to how I can keep the generated leg up durin gthe spindle start.. also the lathe motor is a 7.5hp so the 15 should have done it...

What leg ya got the generated leg on? If it is on the same leg that the lathe is pulling the control power off of you could be dropping the control power too low. BTW, what alarm ya getting? have had similar problems on some machine installs. there are several ways to get around this problem. PM me and I should bw able to get ya going.

Pretty helpful bunch over here too - http://www.practicalmachinist.com/cgi-bin/ubbcgi/forumdisplay.cgi?action=topics&forum=Phase+Converters+and+VFD&number=3&DaysPrune=1000&LastLogin=


Andy

Thanx murch I am a member over there now and have posted the question to them.

And flatbed you have got mail..

ttt

Got the mail man, I'll work it out with ya on the other board or this which ever you prefer. Both have folks that know their shat. :D

Originally posted by Murph
Pretty helpful bunch over here too - http://www.practicalmachinist.com/cgi-bin/ubbcgi/forumdisplay.cgi?action=topics&forum=Phase+Converters+and+VFD&number=3&DaysPrune=1000&LastLogin=


Andy


Andy, thanks for link. Cool site. :D

If you do manage to get it resolved on the other board could you please put the solution here too?:)

Will do

It's funny, you do it everyday for living yet you spend you free time on it. It's a wonder my wife is still with me ( along with a shitload of other reasons ) :D Only thing that would make it better was if I was close enough to go over knock back a few a few :beer: and get running for him. :D

Well guys I am stoked I got it running tonight.. wired up the 10hp RPC and was able to start th 5hp motor I had laying on the floor. so then I moved up to the 7.5 in the lathe with the Mill running and it started ones, every time after that I got the error. So I went back to My caps and reconfigured them and upped the idler back to the 15hp and boom it started with no error in nuetral, So I then put it at 25 RPM and tryed it and it worked then up to 100 and never again so I wired an auto start in the circiut and got rid of the push button. Now when i start it, the normaly closed relay opens when it hits the correct voltage and yanks the start caps out of line machine runs fine all the way up to 2000RPM. And my voltage never goes above 235 on the generated leg and never drops below the 195 so i think I got it Thanx to all that gave input.
_scott

Thanx to a few of Flatbeds suggestions it got the wheels rolling again.. Basically the fix is the auto start when the current is sensed below my preset voltage by a reastat it closes the the N/O contact and allowas the Start caps back in line untill it goes above at which point the diode on the contacter holds it off...

Cool, glad I could I help you. If you ever have any other questions please feel free to get a hold of me. :D

Will do:D

ok i have a question too while the subject is being discussed.

i picked a 3 phase 5HP table saw for a good deal but obviously don't have 3 phase power at home to run this thing. i thought the options were a static, rotary, or motor swap. i THINK a static converter would be fine but honestly don't know much about this stuff. if the HP drops a little, that's fine. 5HP table saw is a little overkill for a home shop anyway. what would be the best route to get the saw running? static, rotary, motor swap. money is an issue but i'd rather it be done right. also, don't want to have electric bills skyrocketing! thanks. i'm browsing the other forum linked above as well.

Rockrat -- cool! I remember your questions a while back, glad you got it up and running. My odd suggestion of wiring up the light bulbs was to give a visual condition of leg voltages when starting up.

Jason -- For your needs, most like a static starter. About $150 for a 5 hp. If you have access to some surplus motors, you can build your own rotary convertor. Basically it is a static convertor + three phase motor (at least 50% larger than your biggest motor, running at 3450 rpm). There is a good chapter in Taunton's Press about "Home Workshops" (check the library) about getting it wired up and running. Just looked on Amazon, and didn't see the book I have -- so check the library first before you order it! (most of my stuff is in storage, but I'll check for it... if I have it I can scan the pages)

Tom :usa:

thanks tom. i'll go see if i can find that one at the library this week for sure.

one more quick question.. i read somewhere that static converters aren't good for a lot of starts per hour. any truth to that?

any recommendations to brand or anything?

Static convertors use a capacitor on the third leg. Lots of starting and stopping will overheat the capacitor, so not recommended.

When I need to start/stop my lathe (2hp) .... uh, I would leave the milling machine (3hp) running. Not good for the bearings, but you get the idea. Static convertor only started up once.... mill kept running after that, lathe kept getting started/stopped as I was checking on machined sizing.

Brand... not really. "Phase-A-matic" seems to be the only brand of static convertors that I have come across. They also sell a "heavy duty model" for more starting/stopping operation.

Find a local electric repair shop. Tell them you need a 7.5+ hp three phase, UGLY is good, surplus motor for a rotary convertor. Usually they can be had for CHEAP ($50???!!!). Take it home, and get a phase convertor to match the HP requirement. Make sure the motor you buy is at least 50% larger than your wood saw. 8hp in your case (that is big!!!). Get a static starter for it... OR learn how to pull a pull rope to get that sucker spinning BEFORE you apply power to it. No not kidding, nor is a pull rope a OSHA approved method. Basically once rotating, it will keep on running once power is applied. Third leg is generated by the back EMF.

One time I was at an auction, and they had a 10 hp three phase motor. Looked brand new, but everyone else commented "damn, some idiot cut off the spindle... it's junk". :D

Tom :usa:

thanks again tom. guess its time to start gathering parts. this is gonna be more hassle than i originally thought. yeah i'll be starting and stopping it pretty often so i guess some form of rotary will be the key. time to look for motor shops!

Good luck on the parts search I pretty much fell into everything except My caps which I purchased. 24x18x20 explsion proof lighting cab. 60 amp with heater protected 3ph contacter, a few 60 amp pump start switches. all for free. I spent $157. on a new dayton 5hp motor for the original mill that I built it for then pulled it and put a new 10hp motor (donated by one of my accounts) and up the caps,$50. then that would not start the lathe so another acount donated Motor 15Hp and anther $50 in caps. a $30 dollar relay, a dimer swtch for the auto start and a diode.
so for under $400. i have what would have cost me at least $6-$800.+ sh you just have to know wher to look for the parts.