Tweco Merlin 6000 Plasma Cutting CE Slave Power Supply - Manual (Page 21)

Manual 0-2603 3-5 INSTALLATION PROCEDURES
C. Creating An Earth Ground
1. To create a solid, low resistance, earth ground, drive a
1/2 in (12 mm) or greater diameter copper clad ground
rod at least 6 - 8 ft (1.8 - 2.4 m) into the earth so that
the rod contacts moist soil over most of its length.
Depending on location, a greater depth may be re-
quired to obtain a low resistance ground (see NOTE).
Ground rods, typically 10 ft (3.0 m) long, may be
welded end to end for greater lengths. Locate the rod
as close as possible to the work table. Install a ground
wire, 1/0 AWG (50.0 mm
2 European) or greater, be-
tween the ground rod and the star ground point on
the cutting table.
NOTE
Ideally, a properly installed ground rod will have a
resistance of three ohms or less.
To test for a proper earth ground, refer to the follow-
ing diagram. Ideally, the reading on the multimeter
should be as follows:
• For 115VAC: 3.0 VAC
• For 230VAC: 1.5 VAC
A-02971
+
_
Meter set to
VAC setting
Machine
Earth Ground
Neutral
Line (Hot)
100W
Light Bulb
115 or 230VAC
WARNING
Use extreme caution. This
test uses live voltage.
115VAC: 3.0 VAC
230VAC: 1.5 VAC
V ~
V
~
VR COM A
Ground Testing
2. Increasing the ground rod length beyond 20 - 30 ft
(6.1 – 9.1 m) does not generally increase the effective-
ness of the ground rod. A larger diameter rod which
has more surface area may help. Sometimes keeping
the soil around the ground rod moist by continuously
running a small amount of water into it will work.
Adding salt to the soil by soaking it in salt water may
also reduce its resistance. When these methods are
used, periodic checking of the ground resistance is re-
quired to make sure the ground is still good.
D. Routing Of Torch Leads
1. To minimize RF interference, position torch leads as
far as possible from any CNC components, drive mo-
tors, control cables, or primary power lines. If cables
have to pass over torch leads, do so at an angle. Do
not run the plasma control or other control cables in
parallel with the torch leads in power tracts.
2. Keep torch leads clean. Dirt and metal particles bleed
off energy, which causes difficult starting and in-
creased chance of RF interference.
3.09 Pilot and Power Lead
Connections
The Slave Power Supply pilot and negative DC power
connects directly to connections inside the Arc Starter Box
and the Power Supply. Make the connections to the per
the following procedure:
1. Remove the cover from the Arc Starter Box.
2. Feed the Slave Power Supply pilot lead through
the boot at the end of the Arc Starter Box.
3. Connect the pilot lead to the pilot connection per
the following procedure:
a. Remove the nut and external star washer from
the pilot connection bolt.
b. Place the ring lug on the pilot wire over the
end of the bolt.
c. Re-install the external star washer and nut to
secure the lead.