Hypertherm Service Bulletin on Plasma Machine Grounding.
Posted: Thu Apr 07, 2022 6:51 pm
From Hypertherm: https://www.hypertherm.com/Download?fil ... &zip=False
From Jim Colt:The cable that goes from the plasma cutter to the cutting slat bed is called the "work cable" by Hypertherm and other plasma cutter manufacturers, has never been called a ground cable. If you are not having any electrical noise related issues and are using an air plasma cutter with blowback start technology (all Hypertherm Powermax systems), then there generally is no need for an earth grounding rod. If you determine you need an earth ground rod it should be installed as follows: 1. Driven about 8' into the ground right next to the cnc table for best effectiveness. 2.Run the work cable from the plasma cutter directly to the ground rod, do not use the clamp, rather the cable should be bolted to the rod. The cable also must be cut to the exact length it takes to get to the rod, so shorten it and do not coil. 3. A short length of the same type and size of multi stranded (do not use less strands or single strand....as RF electrical noise travels on the outside of conductors and most efficiently gets to earth on multistrand cables) should be connected from the ground rod to the slat bed frame (bolted to clean, unpainted metal). If you desire a cable with a clamp as well, connect it (bolted) with the other cables from the ground rod....and leave just enough length with a clamp on the end to clamp to your plate. (note, I have been plasma cutting in my home shop for over 20 years....never once had an issue that required I clamp the work cable to the material) While on the subject...another help for electrical noise related issues on a shop cnc machines is to get a good quality UPS (uninterruptible power supply) as used for office equipment. Plug the 120 volt for your computer and the 120 volt for your drive electronics into the filtered, protected outlets on the UPS. Make sure the UPS is sized for the combined Wattage for the electronics and computer x 1.5
From Hypertherm: https://www.hypertherm.com/Download?fil ... &zip=False
From Jim Colt:The cable that goes from the plasma cutter to the cutting slat bed is called the "work cable" by Hypertherm and other plasma cutter manufacturers, has never been called a ground cable. If you are not having any electrical noise related issues and are using an air plasma cutter with blowback start technology (all Hypertherm Powermax systems), then there generally is no need for an earth grounding rod. If you determine you need an earth ground rod it should be installed as follows: 1. Driven about 8' into the ground right next to the cnc table for best effectiveness. 2.Run the work cable from the plasma cutter directly to the ground rod, do not use the clamp, rather the cable should be bolted to the rod. The cable also must be cut to the exact length it takes to get to the rod, so shorten it and do not coil. 3. A short length of the same type and size of multi stranded (do not use less strands or single strand....as RF electrical noise travels on the outside of conductors and most efficiently gets to earth on multistrand cables) should be connected from the ground rod to the slat bed frame (bolted to clean, unpainted metal). If you desire a cable with a clamp as well, connect it (bolted) with the other cables from the ground rod....and leave just enough length with a clamp on the end to clamp to your plate. (note, I have been plasma cutting in my home shop for over 20 years....never once had an issue that required I clamp the work cable to the material) While on the subject...another help for electrical noise related issues on a shop cnc machines is to get a good quality UPS (uninterruptible power supply) as used for office equipment. Plug the 120 volt for your computer and the 120 volt for your drive electronics into the filtered, protected outlets on the UPS. Make sure the UPS is sized for the combined Wattage for the electronics and computer x 1.5
From Hypertherm: https://www.hypertherm.com/Download?fil ... &zip=False