Machine Grounding And High Frequency Interference Protection; Input And Grounding Connections - Lincoln Electric PRECISION TIG SVM186-A Service Manual

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MACHINE GROUNDING AND HIGH FRE-
QUENCY INTERFERENCE PROTECTION
Locate the Precision TIG® 225 away from radio controlled
machinery. The normal operation of the Precision TIG®
225 may adversely affect the operation of RF controlled
equipment, which may result in bodily injury or damage to
the equipment.
This welder must be grounded! See your local and
national electrical codes for proper grounding meth-
ods.
The high frequency generator, being similar to a radio
transmitter, may cause radio, TV and electronic equip-
ment 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 welder.
2. Direct interference radiated from the welding leads.
3. Direct interference radiated from feedback into the
power lines.
4. Interference from re-radiation of "pickup" by unground-
ed metallic objects.
Keeping these contributing factors in mind, installing
equipment per the following instructions should minimize
problems.
1. Keep the welder power supply lines as short as possi-
ble 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 con-
tact between this conduit and the welder case ground.
Both ends of the conduit should be connected to a dri-
ven ground and the entire length should be continuous.
2. Keep the work and electrode leads as short as possi-
ble and as close together as possible. Lengths should
not exceed 25 ft (7.6m). Tape the leads together when
practical.
3. Be sure the torch and work cable rubber coverings are
free of cuts and cracks that allow high frequency leak-
age.
4. Keep the torch in good repair and all connections tight
to reduce high frequency leakage.
5. The work piece must be connected to an earth ground
close to the work clamp, 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.
INSTALLATION
The ground should be securely made and the ground-
ing 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 along pipe
system can result in re-radiation, effectively making
these members radiating antennas.
6. Keep covers and all screws securely in place.
7. Electrical conductors within 50 ft (15.2m) of the welder
should be enclosed in grounded rigid metallic conduit
or equivalent shielding, wherever possible. Flexible
metallic conduit is generally not suitable.
8. When the welder is enclosed in a metal building,the
metal building should be connected to several good
earth driven electrical grounds (as in 5 (b) above)
around the periphery of the building.
Failure to observe these recommended installation proce-
dures can cause radio or TV and electronic equipment
interference problems and result in unsatisfactory welding
performance resulting from lost high frequency power.

INPUT AND GROUNDING CONNECTIONS

Only a qualified electrician should connect the PRECI-
SION TIG® 225. Installation should be made in accor-
dance with the appropriate National Electrical Code, all
local codes and the information in this manual.
Be sure the voltage, phase, and frequency of the input
power is as specified on the rating plate, located on the
rear of the machine.
208/230 volt models have a NEMA 6-50P plug attached to
the #6-3 input power cord and a NEMA 6 -50R receptacle
is included with the Ready-Pak™ models. Other voltage
models have an #12-3 input power cord but no plug or
receptacle.
Have a qualified electrician provide input power supply to
the receptacle or cord in accordance with all local and
national electrical codes. Use a single phase line or one
phase of a two or three phase line. Choose an input and
grounding wire size according to local or national codes.
Refer to the Technical Specifications page at the begin-
ning of this section. Fuse the input circuit with the recom-
mended super lag fuses or delay type
Using fuses or circuit breakers smaller than recommend-
ed may result in "nuisance" shut-offs from welder inrush
currents even if not welding at high currents.
1 Also called "inverse time" or "thermal/magnetic" circuit breakers;
circuit breakers which have a delay in tripping action that decreases
as the magnitude of the current increases.
PRECISION TIG® 225
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1 circuit breakers.