User Manual Section 7
GFK-2958L May 2021
Earthing and shielding 422
•
Special EMC measures for special applications (e.g. frequency converters, servo drives)
•
Contactors and relay coils must be equipped with the corresponding interference
suppressors
7.3.2 Earthing of Inactive Metal Parts
The earthing of all inactive metal parts reduces the influence of coupled interference. For
this purpose, all inactive metal parts (such as switch cabinets, cabinet doors, support
beams, mounting plates, DIN rails, etc.) must be connected to each other over a large
surface area with low impedance, whereby a uniform reference potential is ensured for all
control unit elements.
Required measures:
•
Removal of the insulating layer around screw connections. Protection of connection
points against corrosion
•
Connection of moving earthed components (cabinet doors, separated mounting
plates, etc.) through short earthing straps with large surfaces
•
Where possible, avoid use of aluminum parts, because aluminum oxidizes easily and is
therefore unsuited for earthing
7.3.3 PE Connection
The connection from earth to the PE (protective earth) connection must be done centrally.
WARNING
In the event of a fault, the earth must never take on a dangerous contact voltage, which is
why it must be connected to a PE conductor.
7.3.4 Unearthed Operation
In the event of unearthed operation, the corresponding safety regulations must be
observed.
7.3.5 DIN Rails
Notes concerning the use of DIN rails:
•
Large-surface, low-impedance attachment on the mounting plate and corresponding
contact with the carrier system using screws or rivets
•
Proper earthing
•
Use corrosion-proof DIN rails
•
Remove the insulating layer on painted, anodized or insulated metal components in the
area around the connection point
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