Hypertherm MAX PRO 200 CNC Connections - Quick Question

I updated the post. Feel free to ask more questions if needed.

tommylight wrote:

@RDA,
Do you have a high voltage/high frequency pilot arc plasma cutter with CPC?
Open it, se where the voltage is taken from, then come back and edit your last post.
As far as I know the MAXPRO 200 is a high frequency/high voltage start machine
That means on starting, there are many thousands of volts flowing around.
Ther are photos on this forum of a THCAD that has been subject to these voltages and burst into flames on a much smaller machine where the torch voltage was picked up in front of the HF start module.
What Tommy is saying is you must connect the THCAD behind the High frequency module to avoid joining this example of what not to do. 

Sorry I somehow missed this one. As I don’t know how the pcb is made and don’t know how it breaks I can’t say much about it specifically.

I just wanted to note that the HF is not formed between the electrode and work. It would be nearly impossible to push the spark made by the HF unit, being it a spark gap, electronic or any other type of ignition unit, from the electrode to work. The distance is far to big and trying to push it through the nozzle would not work.

The voltages present between work and electrode during the ignition phase (typically sub 100ms) are mostly, if not all, induced voltages and these are in the MHz range (much like ohmic sensing).

The pilot voltage is pretty much the OCV and is typically under 300V.

My best guess would be that the divider resistors are your standard resistors and not pulse withstanding as they should.

I’m sorry if people feel like I am trying to argue, it’s not my intention. I just try to ”demystify” this as there are no magical forces involved in here.

Well you are aguing
Blow back torches found on the 40amp-125 amp Thermal Dynamics plasma cutters do not generate high frequency/high voltage
The Maxpro 200 does as its a High Frequency Start
Its your hardware, we have warned you.
It may only be for a few milliseconds but thats long enough.
The THCAD is a very robust device built for plasma cutting but it has its limitations. Read its manual carefully.

I forgot I quoted the maxpro manual there. Up to 10,000 V!
The Thcad is rated for overvoltage of 500 volts.

With care, you can make a voltage divider that will work with
10KV HF,  but you do _NOT_ want to pipe the HF signal anywhere
near the  control electronics.

Much better to tap the sense point from before
the "Tesla coil".  Any DC voltage drop in this coil is minimal
and easily compensated for if needed.
 

Actually for the MAX PRO 200 we may all be in violent agreement.
Since on that machine the torch voltage is taken across the 350 UF output
capacitor, so no HF.  There is no 10KV at the torch terminal since the 10KV is only used
for starting the_ pilot_ arc. This is in contrast to HF start machines that have a
start coil in series with the main plasma voltage.

Hello Everyone!

I thank you for your kind replies. I have been away from the PC for a while fixing the machine!

Nothing has happened, and my THCAD is working perfectly actually, cutting on a daily basis with height correction.
the thcad is thcad-10, so im only feeding divided voltage. even if it has 10.000V peak, which would more easily kill the proma (?), on the thcad side it might reach a 200v peak, which i believe it will handle.

I have put the terminals connected to my proma divider, and the proma is grounded. the terminals are not in the place of the picture, they were placed where the manual tells you to place it! ahah

 


thank you all for your kind help!