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System Manual – MOVIDRIVE® compact Drive Inverters
4
Group drive in VFC mode
Project Planning
4.13
Group drive in VFC mode
In VFC & GROUP operating mode, a group of asynchronous motors can be operated
on one inverter. In this operating mode, the inverter operates without slip compensation
and with a constant V/f ratio. The motors are operated without encoder feedback.
Motor currents
The total of the rated motor currents must not exceed the rated output current of the in-
verter.
Motor cables and
fusing
Comply with the regulations issued by specific countries and for specific machines
regarding fusing and the selection of cable cross sections.
The permitted length of all motor cables connected in parallel is determined as follows:
l
ges
= Total length of the motor cables connected in parallel
l
max
= Recommended maximum motor cable length (
→
n
= Number of motors connected in parallel
No additional fusing is required if the cross section of the motor cable corresponds to
that of the supply system lead. If the cross section of the motor cable is smaller than the
cross section of the power supply cable, you must secure the motor cable against short
circuit for the corresponding cross section. Motor protection switches are suited to this
purpose.
Motor size
The motors in a group must not be more than three motor types apart.
Output filter
Usually no output filter is required for groups with 2 to 3 motors. An output filter HF... is
required if the maximum motor cable length (l
max
) given in the table is not adequate. This
may be the case in large groups (n) or when there are long motor cable lengths connect-
ed in parallel (l
tot
). In this case, the maximum motor cable length is not limited by the limit
value given in the table but by the voltage drop on the motor cable. The sum of the rated
motor currents must not exceed the rated through current of the output filter.
NOTE
The parameter settings apply to all connected motors.
04999AXX
I
I
n
ges
≤
max
Summary of Contents for MOVIDRIVE compact MCH41A
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