Motor Thermal Protection - Danfoss VLT AutomationDrive FC 300 Operating Instructions Manual

3. How to Install
Problems may arise at start and at low RPM values if motor sizes are widely different because
small motors' relatively high ohmic resistance in the stator calls for a higher voltage at start and
at low RPM values.

3.7.3. Motor Thermal Protection

The electronic thermal relay in the frequency converter has received the UL-approval for single
3
motor protection, when par. 1-90
current, I
For thermal motor protection it is also possible to use the MCB 112 PTC Thermistor Card option.
This card provides ATEX certificate to protect motors in explosion hazardous areas, Zone 1/21 and
Zone 2/22. Please refer to the
38
Motor Thermal Protection
is set to the rated motor current (see motor name plate).
M,N
Design Guide
MG.33.A9.02 - VLT is a registered Danfoss trademark
®
VLT AutomationDrive FC 300 Operating
ETR Trip
is set for
for further information.
Instructions
Motor
and par. 1-24