Vacon 100 INDUSTRIAL Technical Manual page 8

• vacon
6
The filter, the cable and the motor form a complex high frequency circuit, which
causes a voltage at the motor with different rise times and peak values depending on
the cable length, type etc. Typical voltage peak values as function of cable length are
as follows:
Due to the inductance in series with the load there is a voltage drop across the dU/dt
filter, decreasing the voltage available for the motor. At full rated current this drop is
typically < 1% at a 690 V system voltage.
Filters are chosen so that their rated current is bigger than the drive current. They
will thermally withstand the same overload specification as the drive.
NOTE! The dU/dt filters are designed for a switching frequency of 2 kHz for a 690 Vac
and 3 kHz for a 500 Vac voltage level. For other switching frequency values, see the
safe operating curves for a specific filter. Do not exceed the values of the safe
operating curves.
NOTE! The dU/dt filters are designed for the maximum output frequency of 50Hz - if
this value is exceeded there is a risk of overheating. If higher output frequency is
requested, the drive output current must be decreased. Derating of drive output
current is shown in table 1.
2
Figure 3. Typical motor voltage p.u. as a function of motor cable length [m]
Motor frequency
50 Hz
60 Hz
100 Hz
Table 1. dU/dt filter current derating as a function of motor frequency
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
dU/dt filter range
Current
Inominal
0.94 x Inominal
0.75 x Inominal