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MACHINE GROUNDING AND HIGH FREQUENCY INTERFERENCE PROTECTION
The Capacitor Discharge Circuit used in the high frequency generator, may cause
many radio, TV and electronic equipment interference problems. These problems
may be the result of radiated interference.
Proper grounding methods can reduce or eliminate radiated interference.
Radiated interference can develop in the following four ways:
1.
Direct interference radiated from the plasma cutter.
2.
Direct interference radiated from the plasma cutting leads.
3.
Direct interference radiated from feedback into the power lines.
4.
Interference from re-radiation of “pickup” by ungrounded metallic objects.
Keeping these contributing factors in mind, installing equipment per the following
instructions should minimize problems.
Keep the plasma cutter power supply lines as short as possible and enclose as
much of them as possible in rigid metallic conduit or equivalent shielding for a
distance of 50 feet (15.2m). There should be good electrical contact between this
conduit and the welder case ground. Both ends of the conduit should be
connected to a driven ground and the entire length should be continuous.
Keep the work and electrode leads as short as possible and as close together as
possible. Lengths should not exceed 25 feet (7.6m). Tape the electrode and work
leads together into one bundle when practical.
Be sure the torch and work cable rubber coverings are free of cuts and cracks
that allow high frequency leakage.
Keep the torch in good repair and all connections tight to reduce high frequency
leakage.
The work terminal must be connected to a ground within ten feet of the plasma
cutter, using one of the following methods.
a)
A metal underground water pipe in direct contact with the earth for ten feet or
more.
b)
A 3/4” (19mm) galvanized pipe or a 5/8” (16mm) solid galvanized iron, Steel
or Copper rod driven at least eight feet into the ground.
The ground should be securely made and the grounding cable should be as short
as possible using cable of the same size as the work cable, or larger. Grounding
to the building frame electrical conduit or a long pipe system can result in re-
radiation, effectively making these members radiating antennas.
Keep all panels securely in place.
All electrical conductors within 50ft (15.2m) of the plasma cutter should be
