Unless your plasma cutter is equipped with low frequency start you may be fighting an unwinnable battle.
You’re likely to have EMI challenges even with low frequency start. Trying to do this with a high frequency machine is likely futile although I’d be delighted to be proven wrong.
You are switching this voltage, like a trigger. You need to know what voltage is there for you to switch it.
I doubt this is your issue anyway. Ensure you put a snub diode on that relay.
What are you using to control the relay?
The spindle output on the controller. Looking like Im needing to scrap the plans for the current plasma torch and get a non hf plasma cutter. Jumped on to a table form and another lad has the same setup I do only with a non hf cutter. Said he has nothing shielded and has had no problems with his.
You cannot power your relay off your controller output.
This is what you need.
Amazon.com: HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger : Industrial & Scientific
KY-019 Relay would this work?
Looks like this guy is successfully using a high frequency cutter with an arduino:
Solving plasma cutter’s high frequency noise problem. - YouTube
I would get one optically coupled. You need all the isolation you can get.
So did a bit more digging this morning and looks like pilot arc is the best for what I’m after…
Blowback has less emi but pilot has it.
Right next to my 3.5mHz transmitter is a little Arduino… it has no issues… at 60W of hf.
@berainlb video, he seems to think a majority of the issues are coming in the usb cable. I’d go for that being a great place to start. It seems to be a very weak link.
If you can tell from the controller board if it’s homing, as in a reboot or does it stop everything and you need to manually reset it?
Just stops and have to reset. USB connection to the laptop drops for a second when it happens
Seems the likely route. But I’d focus on trying to reduce the emission at the source as much as possible by grounding the torch as well as possible before focusing on intrusion through the cable. The less noise to be dealt with the better.
Have you manually operated the plasma and it stops or using the relay. But if you check the voltage through the trigger switch to see voltage and if it is ac or dc. Ssr are usually cheaper for switching ac but quite expensive for dc. Just wondering if spindle control can’t handle the relay coil
So, an automotive relay draws about 150ma, and controller pin can supply around 40ma. I would say that could mess with a controller.
Hey, for what its worth, i built a diy cnc plasma table using an arduino uno, i do have an opto isolator for the arc start but i think the biggest thing is that because i was worried about having the same issues i took some phenolic blocks i had, any insulator would work and i placed them under the actual bed, essentially isolating the work surface from the rest of the table and controls. Mine works like a champ.
Yep. The voltage from the trigger is around 16v. The spindle output is 3v and is able to trigger the auto relay. The laser connection puts out 12v but it’s constant and would need the control wire for the relay. Going to order one as well as get a better torch.
I have the work surface in an ibc tank so was no connection to the rest of the table. I added a ground wire to it with the rest of the table and same issue.
If you try firing the plasma using the trigger while the table is being controlled and it still works that should rule out interference. Then the only issue should be the laser relay issue. Ssr relays usually trigger on 3v minimum and draw very low current.
I don’t have a plasma cutter setup yet but I work with plasma on different applications and Plasma spreads itself about like a leaky garden hose .
Isolate things earth things and keep at it .
Running the controller and computer through an isolation transformer then commoning the earths Might help but you have a can of worms here . Please let us all know if/when how you solve this as it is on the horizion for me later this year.
Kudos to you and good luck
So slight design change. Picked up a Lenovo m73 micro PC and am going to put it and the controller into a metal box of some sort. This way the USB cables won’t be exposed and will only have the controller wires and monitor cable to ferrite the fudge out of. Will also be getting a cnc compatible torch but will try this for now.