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Maintenance of cutting equipment, Cutting cables, Equipotential bonding – Hypertherm MicroEDGE Pro Shape Cutting Control Rev.2 User Manual

Page 32: 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. For example, 

the spark gaps of arc striking and stabilizing devices

should be adjusted and maintained according to the

manufacturer’s recommendations.

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 plasma

cutting installation may be considered for special

applications.