For the lathe, milling machine and 24" X 49" CNC router, I ran four
conductor service to the outlets so I have the neutral at the machine.
I can run the 240VAC only VFD from both hot legs, and I divided the
120VAC loads evenly between the two 120VAC legs.
The 24" X 25" CNC router is powered by a 20A 120VAC outlet, so that's
the opposite of your problem with a 240VAC supply and needing to run
120VAC loads. In my case, I used a large transformer (used, on eBay) to
step up the 120VAC to 240VAC to run the VFD for the spindle motor. The
transformer was more expense and weight and heat in the electrical panel
than I wanted but it was less hassle than running 240VAC to the machine.
If I needed to design a CNC machine for 240VAC with no center neutral,
I'd buy components that run on 240VAC. As others already mentioned,
that's no problem for most devices. Switching power supplies usually
have a switch to select 115/230. although many now automatically switch
or are indifferent to wide input voltages. That should take care of the
linear DC power supplies for stepper motor drives, linear DC power
supplies for 5 or 12 or 24 VDC control voltages, and the computer's
linear power supply. There are plenty of computer monitors that run on
120VAC or 240VAC. For the simple CNC systems I've designed, not having
120VAC at the wall really shouldn't be much of a problem, and could save
money on smaller gauge wiring. Copper is becoming a much more
significant part of machine building lately.
On 05/28/2018 04:42 PM, John Dammeyer wrote:
If you are in the UK or EU it's not such a big deal since the power isn't split
phase 110/220 VAC. PCs, monitors etc are all configured for 220/240 VAC input
as would be your Mill. That means the CNC side is also probably powered from
the same 220/240VAC circuit.
But for North America we have split phase. My Mill was wired for 220VAC in and
has a small transformer (120VAC, 24VAC) to run the power feed and relay logic.
The split isn't wired nor does the switch and contactor handle this.
I could run a 250VA Step down transformer to create 110VAC for the PC and
Monitor (0.8A + 1.7A) or just run them both off 220VAC switched from the same
master switch that runs the mill.
What are others in North America doing for powering their PCs and Monitors?
Separate AC outlet/power bar for the PC?
Thanks
John
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users