Tweco 1000 Merlin(Dec2004) - Manual (Page 30)

INSTALLATION 3-12 Manual 0-2708
To test for a proper earth ground, refer to the following
diagram. Ideally, the reading on the multimeter should be
as follows:
• For 115VAC: 3.0 VAC
• For 230VAC: 1.5 VAC
Art # A-02971
+
_
Meter set to
VAC setting
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
Rod
Ground Testing
CAUTION
No other connections should be made at the
ground rod being tested. This test assumes that
the 115 or 230-VAC source neutral is connected
to the utility earth ground.
2. Increasing the ground rod length beyond 20 - 30 ft (6.1 – 9.1 m)
does not generally increase the effectiveness 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 con-
tinuously running a small amount of water into it will work. Add-
ing 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 required to make sure the ground is still
good.
3. The following illustration shows proper connection of a
customer-supplied ground cable to a grounding stud pro-
vided on the rear panel of the power supply.
Art # A-04371
Ground Cable
Ground Cable Connection to Power Supply
D. Routing Of Torch Leads
1. To minimize RF interference, position torch leads as far as
possible from any CNC components, drive motors, control
cables, or primary power lines. If cables have to pass over
torch leads, do so at an angle. Do not run the plasma con-
trol 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 increased chance
of RF interference.