Tweco ArcMaster 401MST - Manual (Page 34)

ARCMASTER 401MST POWER SOURCE
INSTALLATION, OPERATION AND SETUP 3-4 Manual 0-5287
3.06 High Frequency Interference
Interference may be transmitted by a high frequency
initiated or stabilised arc welding machine in the
following ways.
1. Direct Radiation: Radiation from the machine can
occur if the case is metal and is not properly grounded.
It can occur through apertures such as open access
panels. The shielding of the high frequency unit in
the Power Source will prevent direct radiation if the
equipment is properly grounded.
2. Transmission via the Supply Lead: Without
adequate shielding and filtering, high frequency energy
may be fed to the wiring within the installation (mains)
by direct coupling. The energy is then transmitted by
both radiation and conduction. Adequate shielding and
filtering is provided in the Power Source.
3. Radiation from Welding Leads: Radiated interference
from welding leads, although pronounced in the vicinity
of the leads, diminishes rapidly with distance. Keeping
leads as short as possible will minimise this type of
interference. Looping and suspending of leads should
be avoided wherever possible.
4. Re-Radiation from Unearthed Metallic Objects: A
major factor contributing to interference is re-radiation
from unearthed metallic objects close to the welding
leads. Effective grounding of such objects will prevent
re-radiation in most cases.
3.07 Electromagnetic Compatibility
WARNING
Extra precautions for Electromagnetic
Compatibility may be required when this
Welding Power Source is used in a domestic
situation.
A. Installation and Use - Users Responsibility
The user is responsible for installing and using the
welding equipment according to the manufacturer’s
instructions. If electromagnetic disturbances are
detected then it shall be the responsibility of the user
of the welding equipment to resolve the situation
with the technical assistance of the 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, electromagnetic
disturbances shall be reduced to the point where
they are no longer troublesome.
NOTE
The welding circuit may or may not be
earthed for safety reasons. Changing the
earthing arrangements should only be
authorised 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 equipment. Further
guidance is given in IEC 60974-13 Arc
Welding Equipment - Installation 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, 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 insulation 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.