Lincoln Electric CWT ATC-3, Operator'S Manual

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ELECTROMAGNETIC
COMPATIBILITY (EMC)
CONFORMANCE
Products displaying the CE mark are in conformity with European
Community Council Directive. It was manufactured in conformity
with a national standard that implements a harmonized standard: EN
60974-10 Electromagnetic Compatibility (EMC) Product Standard for
Arc Welding Equipment. It is for use with other Lincoln Electric
equipment. It is designed for industrial and professional use.
INTRODUCTION
All electrical equipment generates small amounts of electromagnetic
emission. Electrical emission may be transmitted through power
lines or radiated through space, similar to a radio transmitter. When
emissions are received by other equipment, electrical interference
may result. Electrical emissions may affect many kinds of electrical
equipment; other nearby welding equipment, radio and TV reception,
numerical controlled machines, telephone systems, computers, etc.
WARNING: This Class A equipment is not intended for use in
residential locations where the electrical power is provided by the
public low-voltage supply system. There may be potential difficulties
in ensuring electro-magnetic compatibility in those locations, due to
conducted as well as radiated disturbances.
INSTALLATION AND USE
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 (grounding)
the welding circuit, see Note. In other cases it could involve
constructing an electromagnetic screen enclosing the power source
and the work complete with associated input filters. In all cases
electromagnetic disturbances must be reduced to the point where
they are no longer troublesome.
NOTE: The welding circuit may or may not be earthed for safety
reasons. Follow your local and national standards for installation and
use. Changing the earthing arrangements should only be authorized
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.
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:
a) other supply cables, control cables, signaling and telephone
cables; above, below and adjacent to the welding equipment;
b) radio and television transmitters and receivers;
c) computer and other control equipment;
d) safety critical equipment, e.g., guarding of industrial equipment;
e) the health of the people around, e.g., the use of pacemakers
and hearing aids;
f) equipment used for calibration or measurement;
g) 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;
h) the time of day that welding or other activities are to be
carried out.
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.
METHODS OF REDUCING EMISSIONS
Public Supply System
Welding equipment should be connected to the public supply system
according to the manufacturer’s recommendations. If interference
occurs, it may be necessary to take additional precautions such as
filtering of the system. 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.
Maintenance of the 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 stabilizing devices
should be adjusted and maintained according to the manufacturer’s
recommendations.
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.
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 these metallic components and
the electrode at the same time. The operator should be insulated
from all such bonded metallic components.
Earthing of the Workpiece
Where the workpiece 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 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 a 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.
Screening and Shielding
Selective screening and shielding of other cables and equipment in
the surrounding area may alleviate problems of interference.
Screening of the entire welding installation may be considered for
special applications.
1
1 Portions of the preceding text are contained in EN 60974-10
“Electromagnetic Compatibility (EMC) product standard for arc welding
equipment.”
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