Tweco CE PAK Master 150XL Without Latch Circuit - Manual (Page 30)

INSTALLATION 3-12 Manual 0-2696
7. Connect torch coolant and gas leads to connectors on
the Torch Bulkhead Panel.
8. Close the Access Panel and turn the two latching
screws.
9. Check the torch for proper parts assembly.
10. Connect the other end of the CNC Control Cable to
the desired equipment.
3.10 Ground Connections For
Mechanized Applications
A. Electromagnetic Interference (EMI)
Pilot arc initiation generates a certain amount of electro-
magnetic interference (EMI), commonly called RF noise.
This RF noise may interfere with other electronic equip-
ment such as CNC controllers, remote controls, height con-
trollers, etc. To minimize RF interference, follow these
grounding procedures when installing mechanized sys-
tems:
B. Grounding
1. The preferred grounding arrangement is a single point
or “Star” ground. The single point, usually on the
cutting table, is connected with 1/0 AWG (European
50 mm
2 ) or larger wire to a good earth ground (refer to
paragraph ‘C’, Creating An Earth Ground). The
ground rod must be placed as close as possible to the
cutting table, ideally less than 10 ft (3.0 m), but no more
than 20 ft (6.1 m).
NOTE
All ground wires should be as short as possible.
Long wires will have increased resistance to RF fre-
quencies. Smaller diameter wire has increased re-
sistance to RF frequencies, so using a larger diam-
eter wire is better.
2. Grounding for components mounted on the cutting
table (CNC controllers, height controllers, plasma re-
mote controls, etc.) should follow the manufacturer’s
recommendations for wire size, type, and connection
point locations.
For Thermal Dynamics components it is recommended to
use a minimum of 10 AWG (European 6 mm
2 ) wire or flat
copper braid with cross section equal to or greater than 10
AWG connected to the cutting table frame. The connec-
tion point must be clean bare metal; rust and paint make
poor connections. For all components, wires larger than
the recommended minimum can be used and may improve
noise protection.
3. The cutting machine frame is then connected to the “Star”
point using 1/0 AWG (European 50 mm 2 ) or larger wire.
4. The plasma power supply work cable (see NOTE) is con-
nected to the cutting table at the single point “Star” ground.
NOTE
Do Not connect the work cable directly to the
ground rod.
5. Make sure work cable and ground cables are properly
connected. The work cable must have a solid connec-
tion to the cutting table. The work and ground connec-
tions must be free from rust, dirt, grease, oil and paint.
If necessary grind or sand down to bare metal. Use
lock washers to keep the connections tight. Using elec-
trical joint compound to prevent corrosion is also rec-
ommended.
6. The plasma power supply chassis is connected to the
power distribution system ground as required by elec-
trical codes. If the plasma supply is close to the cutting
table (see NOTE) a second ground rod is not usually
needed, in fact it could be detrimental as it can set up
ground loop currents that cause interference.
When the plasma power supply is far away from the
ground rod and interference is experienced, it may
help to install a second earth ground rod next to the
plasma power supply. The plasma power supply chas-
sis would then be connected to this ground rod.
NOTE
It is recommended that the Plasma Power Supply be
within 20 - 30 ft (6.1 – 9.1 m) of the cutting table, if
possible.
7. The plasma control cable should be shielded with the
shield connected only at the cutting machine end.
Connecting the shield at both ends will allow ground
loop currents which may cause more interference than
with no shield at all.