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PM 85 voltage divider noise

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PM 85 voltage divider noise

Postby sam-tip » Sun Feb 11, 2018 9:23 am

I am seeing random voltage noise out of pins 5 and 6 of the CPC connector when not cutting. I am seeing the voltage bouncing 0.03 to .1 volts (30 to 100 milli volts). I have turned everything off and unhook all PVM and 485 connections except the torch and still see the bouncing baseline. The plasma table is off and disconnected. I am seeing the same readings on the commandcnc torch voltage display. I was using 50:1 at the divider and just switched to 20:1 with the same readings. With 20:1 scale factor it should help with THC but still a bunch of floating noise.

I have seeing the same results with the hand torch and the machine torch. Both torches are 50 ft.
The CPC and 485 are both field upgrade kits.
Moving the work ground does not change anything.
Even turned off the shop wifi and cell repeater.
Shop has 200 amp service with over sided copper wiring.
Enclosed pole building with metal lining inside and outside.

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Re: PM 85 voltage divider noise

Postby jimcolt » Sun Feb 11, 2018 11:59 am

I believe that electrical noise is normal for the Hypertherm voltage divider output. The divider in these units is simply a does not have isolation, filtration or noise suppression.....which is normally part of the torch height control input. You can contact technical service at Hypertherm for verification, they are at [email protected] or 1 800 643 9878 .

On our industrial systems, since they are much noisier with their high frequency arc starting....we do have isolation circuitry on the available divider modules. Jim Colt Hypertherm

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