I typed "linear" when I was thinking "switching" in the last paragraph.
Unfortunately, I also read "switching" when I proof read what I typed
before sending it to the group. I fixed it in the forwarded text,
below. Sorry for the confusion.
On 05/28/2018 06:55 PM, Bruce Layne wrote:
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 *SWITCHING* DC power supplies for stepper motor drives,
*SWITCHING* DC power supplies for 5 or 12 or 24 VDC control voltages,
and the computer's *SWITCHING* 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
------------------------------------------------------------------------------
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
