Tweco 100 Weldskill - Manual (Page 19)

weldskill 100 iNVeRTeR
3-3 March 3, 2008
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
pacemakers 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 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
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. In
particular, the spark gaps of arc striking and
stabilising devices should be adjusted and
maintained according to the manufacturer’s
recommendations.
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
because 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 taken to prevent the earthing
of the workpiece increasing the risk of injury
to users, or damage to other electrical
equipment. Where necessary, the connection
of the workpiece to earth should be made by
direct connection to the workpiece, 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.