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Maintenance of cutting equipment, Cutting cables, Equipotential bonding – Hypertherm HyIntensity Fiber Laser Rev.3 User Manual

Page 30: Earthing of the workpiece, Screening and shielding

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EMC-2

Compliance Information

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ELECTROMAGNETIC COMPATIBILITY

Consideration should be given to shielding the supply

cable of permanently installed cutting equipment, in

metallic conduit or equivalent. Shielding should be

electrically continuous throughout its length. The shielding

should be connected to the cutting mains supply so that

good electrical contact is maintained between the conduit

and the cutting power source enclosure.

Maintenance of cutting equipment

The cutting equipment must be routinely maintained

according to the manufacturer’s recommendations. All

access and service doors and covers should be closed

and properly fastened when the cutting equipment is in

operation. The cutting equipment should not be modified

in any way, except as set forth in and in accordance with

the manufacturer’s written instructions.

Cutting cables

The cutting 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 cutting

installation and adjacent to it should be considered.

However, metallic components bonded to the workpiece

will increase the risk that the operator could receive a

shock by touching these metallic components and the

electrode (nozzle for laser heads) 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, 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 Equip ment, 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 cutting system

may be considered for special applications.