[gearsoup]

Hey all,

My buddy is kicking around the idea of picking up a few CNC machines. To start, he wants a smallish (able to hold two Kurt vises) VMC, and maybe a CNC lathe. He has been a machinist for a couple decades, so he knows what he is doing....
Here is the problem. He lives out in the middle of nowhere. 3 phase power is literally 5-6 miles away from him. While he is not a poor man, he doesn't have that kind of $$$ to bring in true 3 phase.
So....
Can CNC mills and lathes be hooked up to rotary phase converters? Do I need one for each machine? Do I need to put a line conditioner on it, so the machine sees a constant/consistent feed? AAny thing else I should know?

[gearsoup]

Oh, he already has a lathe and B-port (both 3phase). Compressor is also on the list...

[Al_The_Man]

If there is alot of transformer isolation on the units, (no 3ph motors directly accross the 3phases) Then he will need one large enough for both machines.
If they are currently 460 can they be converted easily from 460 to 220 if neccessary?
Present size of his supply large enough?
Al.

[gearsoup]

He has not purchased the machines yet. Both manual machines are 220 running off of static phase converters. (yuck)
He just built a large garage, specifically for the CNC's, so as yet, power hasn't been hooked up.....

[timlkallam]

Hey al the man I am doing what Gearsoup wants to do .I am running a 15 hp cnc lathe and a 10 hp cnc mil they both have fanuc controls and i run them at the same time.

They are running off or a 30 hp rotery phase converter and
all 3 legs are within 5 volts.

Will runnig both machines at the same time damage the controls? I notice when the lathe starts up the load
indcater goes up to about 150% for about 1 second
this makes the light in the cnc mill go a little dim.

[lilwen]

It has been my experic in working with 3phase elec. that you want to start your largest motor first and I have never had any trouble running other tools as long as my largest was running. We have a sheet metal shop in the sticks and I ran the whole shop exec for wall outlits and lights with 3phase elec running from a idler 60hp 3phase motor that i start up first. with this 60hp started with 2phase 220 and using all three legs out i got all line volts within 2volts and with few caps in system got line balance almost perfect.

[Al_The_Man]

It has been my experic in working with 3phase elec. that you want to start your largest motor first and I have never had any trouble running other tools as long as my largest was running. .

Thats true, but that generally this is when you are running motor loads, as any motor started in the system will aid the RPC.
But the problem comes when the motors are isolated by means of Drives etc, and then you do not have this aid and it becomes pure load to the RPC.
If your wire sizing is marginal then you will experience momentary dips or spikes , which could be a problem for older drives like SCR type.
Al.

[lilwen]

But the problem comes when the motors are isolated by means of Drives etc, and then you do not have this aid and it becomes pure load to the RPC.
If your wire sizing is marginal then you will experience momentary dips or spikes , which could be a problem for older drives like SCR type.
Al.

true so very true. :cheers:

[timlkallam]

My shop is in the back of my house it was built in the 1940s it had a 60 amp main breaker i upgraded every thing to 200 amp service . But I still have the old 1940s wiring going down the street when i hit cycle start my lights blink and a few of my neighbors on the same transformer there lights blink too. They talk about it but they don't know is me .Any way with this drop in power will it
screw up a fanuc control .Will runnig both machines at the same time damage the controls? I notice when the lathe starts up the load
indcater goes up to about 150% for about 1 second
this makes the lights in the cnc mill go dim.
if it is damaging the controls would it throw up an alarm?
My controls are 1996 21t and a 2005 oi mate do these have the scr drive.

[Al_The_Man]

If they are that recent, they should not have SCR drives.
Fanuc and others can be sensitive to voltage drop, but if only momentary you may be OK.
The size of your main feeder is probabally the cause.
Al.

[gearsoup]

Someone I talked to mentioned using 2 phase converters (hooked together...) to even out the voltage. Is this necessary?

I don't know exactly how it gets hooked up, or what it is supposed to accomplish.....

[Al_The_Man]

This is similar to what I touched on in post #7, any 3 phase motors on the system aids the RPC. But that is only if you already have a RPC and it is undersized, If you are starting from scratch, then build/buy one large enough.
Al.

[gearsoup]

Also....

Let's say he buys an average sized CNC. (less than 15 HP motor) Then he buys a CNC lathe. They are less than 30 horse combined. So he goes out and buys a converter for those 2 machines. It should be strong enough to take care of the manual mill as well.... If he adds another CNC in a few months, can he get another converter for that one?
I'm quite confused as to what one actually can get away with.....

[Al_The_Man]

If that is the scenario, he will need either an extra RPC or a larger one, if he gets a second RPC for the 3rd M/C, he could just dedicate that for the new machine, and keep the first two as-is.
As long as his service is large enough, if he intends running all three at once.
Al.