Hypertherm MAX PRO 200 CNC Connections - Quick Question

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01 Oct 2023 09:45 #281974 by tommylight


I believe you assume that the pilot arc and HF are the same thing, they are not.


They ARE the same thing.
HF/HV or HV or Blow Back are used to create the pilot arc, pilot arc is used to make a path for the high current arc.

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01 Oct 2023 10:37 #281976 by RDA


I believe you assume that the pilot arc and HF are the same thing, they are not.


They ARE the same thing.
HF/HV or HV or Blow Back are used to create the pilot arc, pilot arc is used to make a path for the high current arc.
 

Ok, now I get it and now I can see this from your point of view but in regards with the industrial plasma's from all the major manufacturers you are wrong in this case.

Lets take the maxpro as an example in this case as we have the manual and schematics linked in this topic.
- The HF transformer T2 is wired between J5(J3.6) and J4. These are the nozzle and the electrode.
    This transformer is used to make spark between the electrode and the nozzle inside the plasma. The spark ionizes the preflow gas and a pilot arc is formed. The HF is no longer present, typically its there in the sub 100ms range.
- Once the pilot is ignited its sustained by the chopper, or in case of inverter plasma's the inverter. This cannot exceed the OCV of the plasma, in this case 360VDC and typically in the 300VDC range. Also after the pilot has ignited, the HF transformer does not turn ON anymore, until a new ignition is required.
- The arc transfer to the plate is done by the pilot arc, again sustained by a chopper or an inverter, when x amount of current is flowing back also through the work lead (typically in the 5-10A range), the connection to the nozzle is cut and now current only flows from the electrode to the tip. Roughly at the same time as, in this case pilot arc controller "opens", the cutting current is ramped up. Same time also gasses are switched among other things depending on the capabilities of the plasma.


Now I know you don't trust what I am saying and try really hard to convince everyone that
a) I am wrong
b) I have no clue what I am talking about

You can see somewhat the same explanation in the hypertherm youtube video linked by me before.

Last time I remember seeing a HF start plasma that actually transferred the HF to the work piece was probably in the 90's. I remember these big L-TEC plasmas having an electrode like in a TIG. When it wore you could pull it out to be able to cut more. Now I don't say that these do not exists at all anymore, but I am saying none of the major manufacturers do arc transfer this way.

I hope you put your believes aside and try to learn something from this.

I will let anyone reading this post to believe what they want and just add like Tommy said, there is a lot of misinformation in the web so be critical on what you read.

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