Schaffner Group
User and Installation Manual
Output filter FN5420 and RWK5420
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Figure 3 FN5420 maximum cable length by fitler size and fPWM
Step 3: drive switching frequency
The usage of sine wave filter imposes some limit on the switching frequency of the drive (fPWM). The
minimum fPWM is dependant on the filter size and the maximum fPWM is the same for the whole se-
ries, see Table 3 below.
Dv/dt reactor RWK5420 series doesn’t have any minimum fPWM but is still limited to the same maxi-
mum fPWM than sine wave filter FN5420 series. The maximum switching frequency must be reduced
according to the cable length or the cable length must be limited for a given switching frequency.
These limits are giving in the Table 3 and Figure 4 below and in the datasheet.
Table 3 minimum and maximum switching frequency
Filter series
Minimum switching frequency
(fPWM)
Maximum switching frequency
(fPWM)
FN5420 up to 110A
4kHz
16kHz
FN5420 from 145A
2kHz
16kHz
RWK5420 up to 110A
None
4kHz with 100m cable
16kHz with 20m cable
Other values see Figure 4
RWK5420 from 145A
None
16kHz
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2.
3
3.
1
5.
9
10.
2
13.
2
18
26
32
38
45
60
75
90
110
145
180
200
250
302
400
477
630
710
800
1000
M
ax
imu
m c
ab
le l
en
gt
h
[m]
Filter size by rated current [A]
Motor cable length @min. fPWM
Motor cable length @2x min. fPWM
