SC-2 Safety and compliance
ELECTROMAGNETIC COMPATIBILITY EMC
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, for example, ship’s
hull or building steel work, 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
capacitances selected according to national regulations.
Note: The cutting circuit may or may not be earthed for safety reasons.
Changing the earthing arrangements should only be authorized by a
person who is competent to assess whether the changes will in crease
the risk of injury, for example, by allowing parallel cutting current return
paths which may damage the earth circuits of other equipment. Further
guidance is provided in IEC 60974-9, Arc Welding Equipment, Part 9:
Installation and Use.
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 plasma cutting installation may be considered for special
applications.
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