6.17 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
INV
for
the frequency converter.
When motors are connected in parallel, 1-29 Automatic
Motor Tuning (AMT) 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 () 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 for example, thermistors in
each motor or individual thermal relays. (Circuit breakers
are not suitable as protection).
Illustration 6.18
How to Install
VLT
®
Micro Drive FC 51 Design Guide
60 MG02K202 - VLT
®
is a registered Danfoss trademark
66
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