GE AF-600 FP Design Manual page 86

4.4.3 Parallel Connection of Motors
The frequency converter can control several parallel-connected motors. The
total current consumption of the motors must not exceed the rated output
current I for the frequency converter.
INV
NB!
When motors are connected in parallel, par. P-04 Auto Tune cannot be used.
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 (Electronic Thermal Overload) of the frequency
converter cannot be used as motor protection for the individual motor of
systems with parallel-connected motors. Provide further motor protection by
e.g. thermistors in each motor or individual thermal relays. (Circuit breakers
are not suitable as protection).
AF-600 FP Design Guide
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