Multiple Motor Applications - Control Techniques Commander SE Advanced User's Manual

11.3

Multiple motor applications

When more than one motor is to be connected to the output terminals of one drive, the following wiring recommendations
should be followed to ensure that the drive is not prone to spurious overcurrent tripping and that the motors are thermally
protected.
Figure 11-7
Figure 11-8
It is recommended that a single cable is used to serially connect all motors as in Figure 11-7 rather than individual cables
from the drive to each motor as in Figure 11-8.
Where the motors are connected as in Figure 11-7, the total length of the cable should not exceed the recommended
maximum cable length for the drive. If the length does not exceed the recommended maximum cable length, then an output
inductor should be used.
Where it is unavoidable to use individual cables to each motor as in Figure 11-8, an output line inductor must be used, see
Figure 11-9. When the cables and motors are connected in this way, the overall inductance of the cables get smaller because
they are connected in parallel. This has the effect of making the cable capacitance charging currents larger, which may cause
spurious OI.AC trips.
In a multiple motor application, individual thermal overloads must be fitted as in Figure 11-7 and Figure 11-9 to protect each
individual motor. To avoid premature operation of the thermal overloads because of the cable capacitance charging currents,
they should be connected at the motor end of the cables, and as close to the motor as possible.
Commander SE Advanced User Guide
Issue Number: 4
Thermal overloads
Thermal overloads
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