• gratings that guide air flow at the air inlet and outlet
• air inlet and outlet at different sides of the cabinet
• cool air inlet in the lower part of the front door, and an extra exhaust fan on the roof of
the cabinet.
Prevent hot air circulation inside the cabinet with, for example, leak-proof air baffles. No
gaskets are usually required.
The drawing below shows the air flow inside and outside the cabinet.
Air flow in1
Power module2
Hot air circulation to be prevented3
Air flow out4
EMC requirements
Note the following when you plan the electromagnetic compatibility of the cabinet:
• 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 (3.94 in). Pay special attention 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, ABB recommends to
leave the seams between the panels 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
(3.94 in).
Generic cabinet planning instructions 47
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