Planning the cabinet installation
35
EMC requirements
Generally, the fewer and smaller the holes in the cabinet, the better the interference
attenuation. The maximum recommended diameter of a hole in galvanic metal
contact in the covering cabinet structure is 100 mm. Special attention must be paid
to the cooling air inlet and outlet gratings.
The best galvanic connection between the steel panels is achieved by welding them
together as no holes are necessary. If welding is not possible, the seams between
the panels are recommended to be left unpainted and equipped with special
conductive EMC strips to provide adequate galvanic connection. Usually, reliable
strips are made of flexible silicon mass covered with a metal mesh. The non-
tightened touch-contact of the metal surfaces is not sufficient, so a conductive
gasket between the surfaces is required. The maximum recommended distance
between assembly screws is 100 mm.
Sufficient high-frequency grounding network must be constructed in the cabinet to
avoid voltage differences and forming of high-impedance radiator structures. A good
high-frequency grounding is made with short flat copper braids for low inductance.
One-point high-frequency grounding cannot be used due to the long distances inside
the cabinet.
First environment EMC compliance
*)
of the drive requires 360° high frequency
grounding of the motor cable shields at their entries. The grounding can be
implemented by a knitted wire mesh screening as shown below.
*) First environment EMC compliance is defined in chapter Technical data / CE marking in ACS800-04/
04M/U4 Hardware Manual [64671006 (English)].
Cable ties
Knitted wire mesh
Bare cable shield
Cabinet bottom plate
Lead-through plate
Cable
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