Schaffner Group
User and Installation Manual
Output filter FN5420 and RWK5420
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3.3 Power losses
The typical power losses given in Table 4, Table 5 and Table 6 are valid for the rated current at 400V
50Hz. Other measurement points can be calculated for partial load and various frequency usage ac-
cording to Figure 6.
Motor speed 100% is matching the nominal speed at 50Hz. For reduced motor speed, use the curves
given at 90%, 50% or 10%, select the closest one.
Nominal current is given at 100% (right of the chart), for reduced current follow the curve to the left.
For each combination of relative motor speed and relative current, you get a relative power loss in per-
centage. Apply this percentage to the typical power losses given in Table 4, Table 5 and Table 6 to get
the matching typical power loss at the selected operation point. See also an example below.
Note the influence from the voltage between 400V and 500V is minimal and could be ignored in this
calculation.
Figure 6 power loss calculation chart
3.3.1 Power loss calculation example
For a system using a sine wave filter type FN5420-45-92-E0XXT you take the typical power loss given
in Table 4, 272W. This typical power loss is for 400/500V 50Hz at nominal current of 45A.
If you want to calculate the typical power loss at 25Hz motor speed and 36A operation point, you se-
lect the motor speed 50% curve (25/50=50%) and follow the curve up to 80% (36/45=80%) and read
the relative value matching on the vertical axis. You get 60% of relative power loss. You apply 60% to
the typical power loss given in the Table 4, 272*60% = 163W.
In this example the typical power loss at 25Hz, 36A will be 163W.
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