Tweco VAF4 Transmig - Manual (Page 20)

TRANSMIG VAF4
INSTALLATION, OPERATION AND SETUP 3-2 Manual 0-5231
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, signalling and
telephone cables; above, below and adjacent to the
welding equipment.
2. Radio and television transmitters and receivers.
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 pace-
makers and hearing aids.
6. Equipment used for calibration and measurement.
7. The time of day that welding or other activities are
to be carried out.
8. The immunity of other equipment in the environment:
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 surrounding 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 precautions 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 its 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 equipment 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.
3. Welding Cables
The welding cables should be kept as short as
possible and should be positioned close together
but never coiled and 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/grounding of the Work Piece
Where the work piece is not bonded to earth for
electrical safety, nor connected to earth because
of its size and position, e.g. ship’s hull or building
steelwork, a connection bonding the work piece to
earth may reduce emissions in some, but not all
instances. Care should be taken to prevent the earth-
ing of the work piece increasing the risk of injury
to users, or damage to other electrical equipment.
Where necessary, the connection of the work piece
to earth should be made by direct connection to
the work piece, but in some countries where direct
connection is not permitted, the bonding should be
achieved by suitable capacitance, selected according
to national regulations.
6. Screening and Shielding
Selective screening and shielding of other cables
and equipment in the surrounding area may alleviate
problems of interference. Screening the entire
welding installation may be considered for special
applications.