QtplasmaC THC with THCAD-2 negative volt value

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09 May 2023 15:28 - 09 May 2023 15:34 #271034 by brickhousemb
I am running a clean install of QtplasmaC using a Mesa7i76s, a THCAD-5 for hyersensing, and a THCAD-2 (set to a TCHAD10) for THC.  I have an Everlast 102i and I have hooked into the divided voltage pin outs.  I have set the jumper in the machine to 16  The hypersensing works, however, but for the THC I am running into the negative volts issue when cutting (around -24) which also leads to the ArcOK not working.  I understand that due to the everlast's design, the 1/16 read differently.  The best I can figure it reads 1/24 after it is run through the THCAD.  Based on this, the manual, and my specific THCAD I have run the following numbers: 

Full Sacle kHz 900.4 0V Divided kHz 37.51
0V 99.2 divided 4.13
Divider 24
Frequency per Volt 3338.33
Volt Scale 0.009586
Offest 4.133.33

 I think I need to update my hal files to include these new numbers.  I have attached the applicable files.  I can run a backup and post those files tonight (if needed).  I would appreciate any feedback on whether I am correct to use the 1/24 to correct the voltage, and if my math is correct.  If it is correct which file would you update?  Should I make a custom hal file?

Thank you for the help.
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Last edit: 09 May 2023 15:34 by brickhousemb. Reason: Table for numbers did not format

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09 May 2023 19:23 #271059 by rodw
Its been a while but the Everlast confuses the THCAD. The THCAD thinks the everlast's resistors are part of the THCAD's scaling. Do this:
​​​​​Do not use any scaling resistors
Set the Everlast divider to 16:1
Tell the THCAD/Qtplasmac you have a 24:1 divider.
That gives you a 240 volt full scale reading which is perfect!

I found this out after testing with 2 x 48 volt power supplies in series to give 96 volts and measuring with a multimeter.
There is a link in the QTplasmac docs to a calculator to determine the settings to use. Use it to confirm your calculations
​​​​

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10 May 2023 03:00 #271079 by brickhousemb
Yea I have followed your thread to get there I am now.  I put in the numbers in the QrolasmaC GUI this time instead of in the hal and for some reason works.  I also ended up flipping my input to the THCAD wires and it now reads positive.   I did both at the same time so it was too variables and I'm not sure. Actually switching the wires did anything but at any rate it's working. 

I've only done very short 50 mm cuts So I don't think the ArcOK has time to engage.  I'll dial that in soon.  I appreciate the help. 
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10 May 2023 03:06 #271081 by rodw

Yea I have followed your thread to get there I am now.  I put in the numbers in the QrolasmaC GUI this time instead of in the hal and for some reason works. 

This is normal and the expected place to enter the THCAD calibration data.

Glad you are up and runnng

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10 May 2023 17:44 #271116 by PCW

Its been a while but the Everlast confuses the THCAD. The THCAD thinks the everlast's resistors are part of the THCAD's scaling. Do this:
​​​​​Do not use any scaling resistors
Set the Everlast divider to 16:1
Tell the THCAD/Qtplasmac you have a 24:1 divider.
That gives you a 240 volt full scale reading which is perfect!

I found this out after testing with 2 x 48 volt power supplies in series to give 96 volts and measuring with a multimeter.
There is a link in the QTplasmac docs to a calculator to determine the settings to use. Use it to confirm your calculations
​​​​
 

Actually  the divider resistance is always a factor but its normally low enough that is does not cause a significant
error. It must be that the Everlast has a  quite high resistance divider. You can calculate the scaling change by
measuring the divider resistance at the output of the divider  (with the plasma power unplugged) and ideally
the plasma output shorted to ground. This resistance adds directly to the THCADs input resistance (100K)
so changes the scaling factor to nominal_scaling_factor * (100K+divider_output resistance)/100K
 
The following user(s) said Thank You: tommylight, rodw

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