Peak Voltage On Motor - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
The typical values measured at a distance of 1 m from the unit:
FC 301/ FC 302
PK25-P7K5: @ 400 V
PK25-P7K5
Reduced fan speed
Full fan speed
When a transistor in the inverter bridge switches, the voltage across the motor increases by a dV/dt ratio
depending on:
- the motor cable (type, cross-section, length screened or unscreened)
- inductance
The natural induction causes an overshoot U
depending on the voltage in the intermediate circuit. The rise time and the peak voltage U
service life of the motor. If the peak voltage is too high, especially motors without phase coil insulation
are affected. If the motor cable is short (a few metres), the rise time and peak voltage are lower.
If the motor cable is long (100 m), the rise time and peak voltage increases.
In motors without phase insulation paper or other insulation reinforcement suitable for operation with
voltage supply (such as a frequency converter), fit a sine-wave filter on the output of the FC 300.
FC 300 Selection
in the motor voltage before it stabilises itself at a level
PEAK
®
MG.33.B8.02 - VLT is a registered Danfoss trademark
IP20/IP21/NEMA TYPE 1
IP55/NEMA TYPE 12
51 dB(A)
60 dB(A)
PEAK
affect the
65