SIMATIC - ET 200pro motor starter
3-4 GWA 4NEB 950 5661-02 DS 04
3.3 Derating
3.3.1 What is derating?
Derating is the specific deployment of devices with power output restrictions
even under difficult operating conditions. In the case of special modules and
motor starters, these involve operation at high ambient temperatures (> 40°C).
3.3.2 Derating factors
In the case of the ET 200pro special modules and motor starters, the following
factors must be taken into account for deployment in difficult ambient condi-
tions:
• Ambient temperature T
u
:
The ambient temperature T
u
is the temperature surrounding the housing/
enclosure of a special module and motor starter.
The lower the max. ambient temperature T
u
, the higher the current load may
be within the special modules and motor starters.
• Absolute current load:
The lower the current through a special module and motor starter, the lower
the power dissipation (heat loss) in the device. With low inherent heating lev-
els, the ambient temperature T
u
may be higher.
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