Lenze PCM 310 PCMatic Slot Controller - Handbuch (Seite 49)


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47
3.2.2. Installation of wiring shields
The shielding of protected wiring which leads into or out of the switching enclosure must be connected
over a large area to the enclosure immediately at the point where the wiring passes through the casing.
The shielding should extend as far as the PCMatic
®-
card, but it should not be attached there. If the
wiring extends to a second switching enclosure, the shielding should be carried out there in an identical
manner. However, if an external device is attached, e. g. via a SUB-D connector coupling (the
connector socket is mounted directly on the casing of the device), the shielding should be attached
over a large area to this connector housing.
CX/100
Attach shield over
large area
Switching cabinet
Device casing
Do not attach shield
SUB-D connector housing
If there are variations in the interrelationship potential, equalisation currents
may flow across the wiring shield. In this case, the two devices should be
connected by means of a potential equalisation cable.
Shield contact point
The contact point of the shield with the switching enclosure may be formed in one of two ways:
•
The contact point of the wiring shield may be formed by a cable entry with an
earthing element, which attaches the shield concentrically (EMC cable clamp).
This form of contact ensures an optimal shielding effect.
•
The wiring shield may be connected to the switching enclosure by means of a
shield clamp. However, if corrosion occurs, this may reduce the shielding
effect.
It is not recommended to form the earthing link by means of twisting the shield strands.
Twisted shield
strands
Shield clamp
Shield mesh
bad good
PCmatic