Schaffner Group
User and Installation Manual
Output filter FN5420 and RWK5420
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Figure 4 RWK5420 limitation in switching frequency and cable length
Step 4: motor protection and acoustic noise
Output filters are mean to filter the signal coming out of the drive feeding the motor. Filter type dv/dt
reactor, like RWK5420 series, allow to reduce the voltage rise (dv/dt) visible by the motor. This re-
duces the stress on the motor insulation, reduce the temperature of the motor and thus increase its
total lifetime.
Sine wave filter offers more in terms of motor protection by providing a sinusoidal phase to phase volt-
age to the motor, this will bring the stress on the insulation and the temperature rise to the minimum
physically possible level. In addition, the usage of sine wave filter reduces the current flowing between
the rotor and the stator through the motor bearing (i.e. bearing current)
, increasing further more the
service life time of the motor. Finally, sine wave filter reduces motor acoustic noise, improving the
comfort at the facility where the motor is installed.
*
In case of problem with bearing current, sine wave filter plus addons type FN5030 would eliminate the flashover created at
switching, increasing even more the bearing total lifetime.
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Cable length [m]
fPWM at 400V
fPWM at 480V
