Siemens SINUMERIK 840D sl Manual page 50

Structure of the drive group
2.6 Heat Dissipation of the Control Cabinet
Figure 2-26
Caution
The air guidance and arrangement of the cooling equipment must be chosen in such a way
as to prevent condensation from forming.
If necessary, cabinet enclosure heating may have to be installed.
If air conditioners are used, the relative air humidity of the expelled air increases as the air in
the air conditioner cools and may exceed the dew point. If the relative humidity of the air
entering the SINAMICS equipment is over 80% for an extended period of time, the insulation
in the equipment may fail to function properly due to electrochemical reactions (see System
Overview). Using air baffle plates, for example, you must ensure that the cold air expelled
from the air conditioner mixes with warm air in the cabinet before it enters the equipment.
This reduces the relative air humidity to uncritical values.
2-30
Examples of cabinet ventilation
Guide for the SINUMERIK 840D sl machine configuring
Manual, 07/2006 Edition, 6FC5397-6CP10-0BA0