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SAFETY
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INSTRUCTIONS FOR ELECTRO- MAGNETIC COMPATIBILITY
Conformance
Products displaying the
Products displaying the CE mark are in conformity with European Community Council Directive 89/336/EEC require- ments for EMC by implementing EN50199 "Electromagnetic Compatibility (EMC) – Product standard for arc welding equip- ment".
Products are:
•For use with other Lincoln Electric/LiquidArc equipment.
•Designed for industrial and professional use.
Introduction
All electrical equipment generates small amounts of electromagnet- ic 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 effect many kinds of electrical equipment: other nearby welding equipment, radio and TV trans- mitters and receivers, numerical controlled machines, telephone systems, computers, etc. Be aware that interference may result and extra precautions may be required when a welding power source is used in a domestic establishment.
Installation and Use
The purchaser/user is responsible for installing and using the weld- ing equipment according to the manufacturer’s instructions. If elec- tromagnetic disturbances are detected then it shall be the responsi- bility of the purchaser/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 (ground- ing) the welding circuit (see note below). 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 rea- sons according to national codes. Changing the earthing arrange- ments should only be authorized by a person who is competent to assess whether the changes increase the risk of injury, eg. by allowing parallel welding current return paths which may damage the earth circuits of other equipment.
Assessment of Area
Before installing welding equipment the purchaser/user shall make an assessment of potential problems in the surrounding area.
The following shall be taken into account:
•Other supply cables, control cables, signalling and telephone cables above, below and adjacent to the welding equipment;
•Radio and television transmitters and receivers;
•Computer and other control equipment;
•Safety critical safety equipment, eg. guarding of industrial equipment;
•The health of people around, eg. the use of pacemakers and hearing aids;
•Equipment used for calibration or measurement;
•The immunity of other equipment in the environment. The purchaser/user shall ensure that other equipment being used in the environment is compatible. This may require additional protection measures;
•The time of the 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
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 the mains supply. Consideration should be given to shield- ing the supply cable of permanently installed welding equipment in metallic conduit or equivalent. Shielding should be electrically con- tinuous throughout its length. The shielding should be connected to the welding power source so that good electrical contact is main- tained between the conduit and the welding power source enclo- sure.
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 adjust- ment covered in the manufacturer’s instructions. In particular, the spark gaps of arc initiation and stabilizing devices should be adjust- ed and maintained according to the manufacturer’s recommenda- tions.
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, eg. 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 work pieces 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 coun- tries 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.
Portions of the preceding text are extracted from:
•Australian/New Zealand standard AS/NZS 3652. Permission to reproduce has been granted by Standards Australia and Standards New Zealand. For further explanation, readers should be referred to the standard itself.
•British Standards Institution standard BS EN 50199:1995. Reproduced with permission of BSI under license number 2000SK0631. Complete standards can be obtained from BSI Customer Services, 389 Chiswick High Road, London W4 4AL.
United Kingdom. (Tel +44 (0) 20 8996 9001).
Copyright of above text is property of Standards Australia, Standards New Zealand and British Standards Institution. Permission to reproduce the text must be obtained.
JAN ‘01