Plasma emi issues, electrical engineers help

[4130metalworks]

I have been having some weird issues with cutting on my plasma, and from what I have read it could be a build up of emi that releases after a while. My plasma is wired as follows

plasma cutter work lead to earth stake
earth stake to buss bar on the table, that is looped to multiple points on the frame and has a short lead with clamp for the metal getting cut
plasma is 3 phase and off a separate plug to masso controller

masso dthc and myohmic pro in a separate steel box diagonally opposite side to the masso (approx 2.5m distance), double shielded wires except for 24 volt supply

masso, relays, power supplies all in control box
all motor power and encoder wires double shielded
limit switches double shielded
power supply cables double shielded
all wiring other than alarm from motor drivers double shielded

all drains on controller end to central buss bar, that is connected to the ac mains earth
some 24 volt power supply wires and relay module wires are only twisted pair

240 volt input power for power supplies have an emi filter
x axis is grounded to table frame

only the plasma and air compressor is operating at the same time
there is a 24 volt water pump to spray water when cutting that is powered off the relays, could be introducing noise
should the controller box be grounded to the table?
ferrite beads maybe?
I am working in a tin shed
Masso g3 touch
Thermacut 75sd

Problems only arise after cutting for a while, such as torch crashes, no torch touch, plasma runs through g code but doesn't fire

[SegoMan DeSigns]

I too run a Masso controller (G3 / non-touch) I have upgraded my earthen rod / buss bar lead to the same size of welding cable(#4) as the work lead on the plasma cutter (Hypertherm 105). The #4 welding cable is routed through the E-Link to ground both the gantry & Z Axis. Everything is grounded to the common bus bar. Control / sensor cables are STP Cat 5E or nylon braided Cat 7 shielded (E-Link) grounded at common buss bar end only.

Is the wiring in the tin shed up to code? Does it have a main panel with ground rod or is it a sub panel with grounding wire back to the main panel w/ grounding rod? What version of software on the G-3 is being used? My EMI problems are mostly cured but the WIFI gets zapped on the higher amperage cuts. The rapid boot time of the Masso fixes the WIFI.

[4130metalworks]

Thanks for your reply segoman. Thats a fairly hefty cable, is there any reason it needs to be that large?
Only my work lead and earth rod are that big, the other 4mm
Is your hypertherm case grounded as well?

As far as I understand we can only have one main ground rod at the switchboard here in Australia. The shed has its own switchboard and shares this ground

The software is the latest masso stable v5.07
I did see this tutorial by ross for grounding which i will try

[SegoMan DeSigns]

All of my devices (240 V single and 3 ph) are grounded at the buss bar including the work lead from the plasma box. From there a separate work lead is routed to the top of the table via a magnetic clamp. The only time I use the work lead mag ground is when the material is painted or excessively rusty.I will buff a spot clean with a flap disc prior to attachment.

I started out with a section of # 6 THHN from the bus bar to the earthen rod, I still had a static problem so I ran a #6 welding cable from the gantry through the E-Link and onto the buss bar / earthen rod. That cured my static problem. Then I upgraded from a Hypertherm 65 to a 105 and had to upgrade to a #4 (like the 105 has) problem cured again.

Static bugs are hard to trace and exterminate sometimes. The high value targets are the control / power wire to Z and the home / float switch which are in close proximity to the torch. My E-Link is metal so I'm sure that was part of my problem along with having the torch lead ran in the E-Link.

[4130metalworks]

thank you segoman, looks like i need to spend some more time running grounds. From what i have read the emi runs around the outside of the cable so having larger cables like yours is very beneficial

only one I am not sure about is grounding the plasma cutters case to the buss bar