PE ground
PE ground is the grounding system inside the electrical equipment. The PE ground, which
connects to the service ground, provides electrical continuity between the equipment and the
Alternating Current (AC) service.
DC power ground
DC power ground (also known as cutting current ground or work) is the grounding system that
completes the path of the cutting current from the torch back to the plasma cutting system.
It requires that the positive cable from the plasma cutting system be firmly connected to the
cutting table ground bus with a correctly sized cable. It also requires that the slats, on which the
workpiece rests, make firm contact with the table and the workpiece.
EMI grounding and shielding
EMI grounding and shielding is the grounding system that limits the amount of EMI emitted by the
plasma cutting system and motor drive system. It also limits the amount of EMI that is received by
the CNC and other control and measurement circuits. The grounding practices described in this
section mainly target EMI grounding and shielding.
Grounding practices
When you set up an XPR cutting system, make sure that you comply with all best practices for correctly
grounding the system.
■
Unless noted, for XPR cutting systems, use cables with a minimum gauge of 21.2 mm
2
(4 AWG)
(047031) for the EMI ground cables shown in the Example grounding diagram with a plasma cutting
system on page 76.
■
The cutting table is used for the common, or star, EMI ground point and should have threaded studs
welded to the table with a copper bus bar mounted on them. A separate bus bar should be mounted
on the gantry as close to each motor as possible. If there are motors at each end of the gantry, run a
separate EMI ground cable from the far motor to the gantry bus bar. The gantry bus bar should have a
separate, heavy EMI ground cable 21.2 mm
2
(4 AWG; 047031) to the table bus bar. The EMI ground
cables for the torch lifter and the Remote High Frequency (RHF) console or combined ignition/gas
connect console must each run separately to the table ground bus.
■
Inadequate grounding not only exposes operators to dangerous voltages, but inadequate grounding
also increases the risk of equipment failure and unnecessary downtime. Ideally a ground should be
zero ohms resistance, but field experience indicates under 1 ohm resistance is satisfactory for most
applications. Hypertherm recommends that you consult your national and local electrical codes to
make sure that the grounding and shielding practices that you use comply with the requirements for
your location.
Qualifications and Requirements
2
73811530Instruction ManualXPR460
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