[millman52]

It seems that Hypertherm & Thermal Dynamics are the leading couple machines that table builders are using. Is there a reason , Other than price That I am not seeing posts with Miller, ESAB, Hobart, HTP America, etc. machines used?

[Mike@Torchmate]

Some other machines are a High Frequency unit, other's are not a contact start. I suppose it is mainly just manufactures choice, we have several customers running unit's other then Hypertherm and Thermal Dynamics. However it is harder to support the machine when you don't know much about the plasma cutter they are using.

[Perp]

I would like to have some information on this as well, I was planning on buying a Miller Spectrum 1000. I really like my Miller 251 welder.

[Torchhead]

The reason you see the Hypertherm and TD mentioned so much is that they are machine control "friendly" meaning they have easy to identify connection points for doing automated cutting. Miller may well have the same features but since there have not been many posts about Miller or other brands the evolved level of knowledge is not as great. That is not to say they won't work. We have our Digital Torch Height control working on Millers, ESAB's Lincoln, Hypertherm, TD and few brands I've never heard of. We send a current sense transformer with the units that can used with about any machine. One area that we have seen problems with is the smaller inverter type plasma units that do not incorporate PFC (Power Factor Control). Since our CT is design to since the 60HZ current waveforms if the unit has a really poor Power Factor (only draws big peak currects during a small percentage of the waveform) it won't work with the small inverter types. There is a work around but it costs about $50 extra for a different CT transformer.

Its a lot less frustrating to have a plasma unit that already has an Arc Good signal and connection points to fire the torch and sense the tip volts. It can be done with virtually all plasma except the cheap tip contact start types starting to appear from China.

Tom Caudle
www.CandCNC.com

[Al_The_Man]

One area that we have seen problems with is the smaller inverter type plasma units that do not incorporate PFC (Power Factor Control). Since our CT is design to since the 60HZ current waveforms if the unit has a really poor Power Factor (only draws big peak currects during a small percentage of the waveform) it won't work with the small inverter types.

Many of the HSU I have come across sense the DC side which would overcome the PF problem, I realize the CT is an easier way to isolate the sense circuit, but I would think the DC side would be more accurate?.
Al.

[Torchhead]

Sensing the DC side without breaking and inserting inline sensors would require some creative design. It's easy if you can insert a heavy coil of wire wrapped around a Reed switch ( they way a lot of Plasma units still do it) into the DC current path. WIth no AC to perform magnetic transfer just wrapping the wire does not work. The whole current has to go throught the coil. It also needs to be designed for a specific current range. The next option is to do a passthrough ferrite core for the workclamp and use Hall Effect sensors in the magnetic path. All of that takes some modification of the ferrite or the purchase of an expensive ferrite sensor device ($50.00 USD or more). The biggest disadvantage is the Hall Effect approach means added electronics and a power source. Then there is the noise that sensitive electronics wrapped around a workclamp wire would have to deal with.

I would say well over 2/3's of our customers have units that have the Arc Good signal available anyway.

There are several ways to do it. To do it cheaply is the rub

Tom Caudle
www.CandCNC.com