Tweco 550i Transmig - Manual (Page 22)

TRANSMIG 350i, 450i, 550i
INSTALLATION, OPERATION AND SETUP 3-2 Manual 0-5205
manufacturer. In some cases this remedial action
may be as simple as earthing the welding circuit,
see NOTE below. In other cases it could involve
constructing an electromagnetic screen enclosing
the Welding Power Source and the work, complete
with associated input filters. In all cases, electro-
magnetic disturbances shall be reduced to the
point where they are no longer troublesome.
NOTE
The welding circuit may or may nor be
earthed for safety reasons. Changing the
earthing arrangements should only be au-
thorised by a person who is competent to
assess whether the changes will increase
the risk of injury, e.g. by allowing parallel
welding current return paths which may
damage the earth circuits of other equip-
ment. Further guidance is given in IEC
60974-13 Arc Welding Equipment - Instal-
lation and use (under preparation).
B. Assessment of Area
Before installing welding equipment, the user shall
make an assessment of potential electromagnetic
problems in the surrounding area. The following
shall be taken into account
1. Other supply cables, control cables, signal-
ling and telephone cables; above, below and
adjacent to the welding equipment.
2. Radio and television transmitters and receiv-
ers.
3. Computer and other control equipment.
4. Safety critical equipment, e.g. guarding of
industrial equipment.
5. The health of people around, e.g. the use of
pacemakers and hearing aids.
6. Equipment used for calibration and measure-
ment.
7. The time of day that welding or other activities
are to be carried out.
8. The immunity of other equipment in the en-
vironment: the user shall ensure that other
equipment being used in the environment
is compatible: this may require additional
protection measures.
The size of the surrounding area to be considered
will depend on the structure of the building and
other activities that are taking place. The surround-
ing area may extend beyond the boundaries of the
premises.
C. Methods of Reducing Electromagnetic Emissions
1. Mains Supply
Welding equipment should be connected to the
mains supply according to the manufacturer’s
recommendations. If interference occurs, it
may be necessary to take additional precau-
tions such as filtering of the mains supply.
Consideration should be given to shielding the
supply cable of permanently installed welding
equipment in metallic conduit or equivalent.
Shielding should be electrically continuous
throughout it’s length. The shielding should
be connected to the Welding Power Source
so that good electrical contact is maintained
between the conduit and the Welding Power
Source enclosure.
2. Maintenance of Welding Equipment
The welding equipment should be routinely
maintained according to the manufacturer’s
recommendations. All access and service
doors and covers should be closed and
properly fastened when the welding equip-
ment is in operation. The welding equipment
should not be modified in any way except for
those changes and adjustments covered in
the manufacturer’s instructions. In particular,
the spark gaps of arc striking and stabilising
devices should be adjusted and maintained
according to the manufacturer’s recommenda-
tions.
3. Welding Cables
The welding cables should be kept as short
as possible and should be positioned close
together, running at or close to the floor level.
4. Equipotential Bonding
Bonding of all metallic components in the
welding installation and adjacent to it should
be considered. However. Metallic components
bonded to the work piece will increase the
risk that the operator could receive a shock
by touching the metallic components and
the electrode at the same time. The operator
should be insulated from all such bonded
metallic components.
5. Earthing of the Workpiece
Where the workpiece is not bonded to earth
for electrical safety, nor connected to earth be-
cause of it’s size and position, e.g. ship’s hull
or building steelwork, a connection bonding
the workpiece to earth may reduce emissions
in some, but not all instances. Care should be