Powermax 45xp lost arc delay (Solved)

rodw wrote: Assuming you are using the 45XP's ArcOK and not synthesised arcOK which might cause a whole other bundle of pain.

An you advise the THC Delay you are using?

This thread I posted today I think is relevant.

forum.linuxcnc.org/plasma-laser/41420-arc-voltage-on-piercing

My guess is that you are auto sampling too early because your THC delay is too short. Lets say you sampled when the torch voltage was say 50 volts higher than cut volts. Given a volts per mm of between 7.53-10 volts, the THC will immediately attempt to raise the torch by 5-7mm and thus loose the arc...

Please do some plots of your machine using halscope as I have in the other thread before setting your THC delay.

Rod, what you posted is really cool. I am loving how much can be done with LinuxCNC and plasmac. I don't know how to replicate using halscope but I will give it a try and see if I can bluff my way through.

To answer your questions. I am indeed using hypertherms arc ok signal. And as for the delay, I originally had it at 1.5s because that is how it was set out of the box, but then I changed it to 0.5s because I thought it would be better if the THC got involved sooner rather than later when moving pretty fast to cut 14 gauge material. Now with your trick hopefully I can figure out how to plot it to know exactly when the arc is stable and set the delay to that.

Yes, the 1.5 seconds came pretty much from the plot in the plasma primer (and many more around that time). I actually went and did that test to answer a question on this thread becasue Tommy's advice sounded wrong to me...
forum.linuxcnc.org/plasmac/41200-thc-tes...up-and-down-movement

Now I am not so sure...

When I did those plots, I did take some video to explain how to use Halscope but it will take time to publish it. It is documented though...

linuxcnc.org/docs/devel/html/hal/tools.html#sec:halscope

Nick7251 wrote: You are correct in assuming I am using the solid state relay on the 7i96 board. Might need to switch over to a mechanical relay to remedy this issue

I had very similar issues you are having on my everlast 50s plasma cutter while using a solid state relay before my mechanical relay arrived, I then changed to the mechanical relay and it fixed the problem on startup, I still have issues losing arc on a lead out but only if i have too big of a lead out, I dont lose it when set to 2mm but this issue isnt really related to your startup problem, but potentially one you may face. I now have a powermax 65 and do not have any issues on startup.

Also I set the thc delay to 1 second and this seems to work for me.

the term dry contact does not mean a mechanical relay. It means that there are two seperate power sources in play. eg our control box power is switching the plasma's circuit.

Dry contacts can be solid state relays. I use a opto isolated SSR which is switched by my 7i76e as my dry contact.

Dry contacts are used in all types of relay, including a solid-state relay.

Ref: www.electrical4u.com/dry-contacts/

I have thought of using the 7i76e spindle relay which would result in machine with no added external relays. It seems ts only good for 50mA which sounds a bit low. I still don't understand why the 7i96 outputs are problematic.

Remember though that most SSR's are polarised.

-Solid state relays do NOT have any type or kind of contact
-i am skipping the "dry contact" thingy all together, old relic still schlepped around used and miss used as a lot of other things.
-some of you are causing more confusion than helping the poor guy fix and use his machine.
Trying with a normal relay seems a good start.

Guess it's my fault, I said "dry contact" and not "dry contact closure". So I edited my post (in this thread) that mentioned it, and I will correctly quote the manual here:

From the Hypertherm owner's manual (65-85 but I'd bet the others are similar):

With reference to Start (start plasma or Torch On): "Normally Open. Requires dry contact closure to activate."

With reference to Transfer (start machine motion or Arc Ok): "Normally open. Dry contact closure when the arc transfers."

Being as they are using the same term "dry contact closure", and seeing as I took apart my Hypertherm and found the exact part number for the mechanical relay they use, we could safely apply logic and deduct that they are wanting the end user to use a mechanical relay to provide dry contact closure and start the torch. Also, further logic applied could take us to the fact that a manual torch uses a simple momentary on off switch to start the torch. Neither are SSR's and therefore, a mechanical relay should be used (as the manual states).

I suspect there is not enough amperage to properly bias the SSR, and Hypertherms are particularly sensitive to this.