Parallel Connection Of Motors - Danfoss VLT Micro Drive FC 51 Design Manual

How to Install

6.17 Parallel Connection of Motors

The frequency converter can control several motors
connected in parallel. When using a parallel motor
connection, consider the following points:
•
When motors are connected in parallel, parameter
1-29 Automatic Motor Tuning (AMT) cannot be
used.
•
Run applications with motors connected in
parallel in U/F mode (volts per hertz).
•
The usage of VVC
applications when the motors connected in
parallel are of the same type and size.
•
6 6
Total current consumption of motors must not
exceed the rated output current I
frequency converter.
•
Significant difference in motor sizes may cause
problems at start and at low RPM. The relatively
high ohmic resistance in the stator of a small
motor demands higher voltage at start and at
low RPM.
•
Do not use the electronic thermal relay (ETR) of
the frequency converter as motor protection. To
provide extra motor protection, include
thermistors in each motor winding or individual
thermal relays.
During the installation of a parallel motor application,
consider the following points:
•
Connection A/B is only possible when the total
motor cable is shorter than 50 m (164 ft).
•
In connection C/D the total motor cable length
specified in general specifications is valid as long
as the parallel cables are less than 10 m (32.8 ft).
54
®
VLT Micro Drive FC 51
+
mode is limited to certain
of the
INV
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Illustration 6.18 Parallel Connection of Motors
MG02K402