Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jim young on August 15, 2021, 02:42:49 PM
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hi; my cnc plasma table running on mach 3 proma thc computer windows 10 goes completly crazy when the torch fires losing all functions any help thanks . jim
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Poor shielding of cables, not enough earthing, no common earthing between devices and many many more can cause this.
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Hi,
a plasma arc is like 'controlled lightning' going off on a machine connected to a computer. Most people would
say mixing lightning and a PC is foolish...and they'd be right.
One often overlooked source of electrical noise getting into your PC/controller/BoB is via the power supplies.
When plasmas operate they draw a great deal of current from the incoming domestic AC supply. Most modern plasmas are
electronic in nature and most, certainly all the Chinese ones, have no power factor correction built in, and thus they pollute the domestic supply
with very troublesome current harmonics. These harmonics are easily conducted into the PC power supply and the controller/BoB
supplies and play merry hell.
You might try as an experiment plugging the plasma into a separate circuit than the PC/controller/BoB. If this helps then
I would recommend a line reactor at the input of the plasma, it will seriously tame those current harmonics. Also a two, or even better three stage,
line filter at the AC input to your PC/controller/BoB will help keep conducted noise out of those components. Don't scrimp, get the gest line filters
you can afford.
This is a 3 phase line reactor, which if you wire all three windings in parallel with careful attention to the phase dots, will give you an excellent
12A line reactor:
https://nz.element14.com/block/lr3-48-3-4/line-reactor-3-phase-5-5mh-4a/dp/2751043 (https://nz.element14.com/block/lr3-48-3-4/line-reactor-3-phase-5-5mh-4a/dp/2751043)
This is a suitable 10A two stage line filter:
https://nz.element14.com/corcom-te-connectivity/10emc1/filter-10a-1-phase/dp/9586474?st=line%20fiters (https://nz.element14.com/corcom-te-connectivity/10emc1/filter-10a-1-phase/dp/9586474?st=line%20fiters)
Over and above preventing conducted electrical noise from entering the power supply input of your PC/controller/BoB
you must now turn to minimising the susceptibility to noise.
Is your controller USB connected? USB connections are very susceptible. Make the connection as short as possible, preferably
with a ferrite ring core close to each end, or even better get an Ethernet connected controller, they are better in a noisy environment.
Craig