Peak Voltage On Motor; Tion - Danfoss 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

Peak Voltage on Motor

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 overshot U
depending on the voltage in the intermediate circuit . The rise time and the peak voltage U
the 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.
If very small motors are used without phase coil insulation, connect an LC filter to the frequency con-
verter.
FC 300 Selection
in the motor voltage before it stabilises itself at a level
PEAK
MG.33.B7.02 - VLT is a registered Danfoss trademark
IP20/IP21/NEMA TYPE 1
IP55/NEMA TYPE 12
51 dB(A)
60 dB(A)
affect
PEAK
59