How To Select Your Vlt; Peak Voltage On Motor - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide

How to Select Your VLT

Peak Voltage on Motor

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When a transistor in the adjustable frequency drive is opened, the voltage across the
motor increases by a dV/dt ratio depending on:
the motor cable (type, cross-section, length shielded or non-shielded)
-
inductance
-
The natural induction causes an overshot 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, motors without phase coil insulation in particular
are affected. If the motor cable is short (a few meters), the rise time and peak voltage are lower.
If the motor cable is long (300 ft / 100 m), the rise time and peak voltage increase.
If very small motors are used without phase coil insulation, connect an LC fil-
ter to the adjustable frequency drive.
in the motor voltage before it stabilizes itself at a level
PEAK
MG.33.B3.22 - VLT is a registered Danfoss trademark
affect the
PEAK
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