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5 Application notes
-
Note the operating diagrams for power reductions (derating) in the instructions.
-
he temperature of the cold plates of the frequency inverters must not exceed
T
kmax
= 75 °C for a nominal power of 0.55...3.0 kW and T
kmax
= 70 °C for a nominal
power of 4.0...18.5 kW.
-
Additional power losses P
v int
are dissipated as heat into the interior of a control
cabinet. These losses may amount to 30% of the total ener
y dissipation and mus
be considered in the calculation of the volume of the control cabinet. The values
are listed in the tables in chapter "Thermal resistance".
-
If several frequency inverters or other heat-producin
devices are mounted on a
common heat sink (sum cooler), the losses of all devices must be added up. Calcu-
late the max. permissible thermal resistance R
th
using the formula (chapter "Ther-
mal resistance").
-
The contact surface of the heat sink must at least be as large as the contact sur-
face of the cold plate of the frequency inverter.
-
The contact surfaces of the heat sink and the cold plate of the frequency inverte
must be plane.
-
Black anodized heat sinks are particularly suitable. If free convection is guaran-
teed, these heat sinks have a thermal resistance which is 5…10% lower than tha
of untreated heat sinks.
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