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

FC 300 Operating Instructions
Parallel connection of motors
The FC 300 is able to control several
parallel-connected motors. The total current
consumption of the motors must not exceed the
rated output current I
INV
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.
The electronic thermal relay (ETR) of the FC 300 cannot be used as motor protection for the individual motor
in systems with motors connected in parallel. Further motor protection must be provided, e.g. thermistors in
each motor or individual thermal relays. (Circuit breakers are not suitable as protection).
NB!:
When motors are connected in parallel, parameter 1-29 Automatic motor adaptation (AMA)
cannot be used.
For more information, see VLT AutomationDrive FC 300 Design Guide.

Motor Thermal Protection

The electronic thermal relay in FC 300 has received the UL-approval for single motor protection, when par.
1-90 Motor Thermal Protection is set for ETR Trip and par. 1-24 Motor current, I
motor current (see motor name plate).
26
How to Install
for the FC 300.
MG.33.A2.02 - VLT is a registered Danfoss trademark
is set to the rated
M,N