Written by: Daniel C. Merkel
More and more applications are requiring multiple motors driven by a single VFD. Such
applications include multiple exhaust fans, pumps or the most common: Fan Wall.
In short, YES! A VFD is able to power multiple motors. Note: all motors operating by a single
VFD will operate at the SAME FREQUECY.
As we develop a design for this system to work properly, we need to account for some additional
criteria including the:
Length of Wire Runs
Proper VFD Sizing
Branch Circuit Protection and Distribution
The wire distance runs to the motors need to be summed up as well. For example, if there is an
application with four (4) motor and the VFD is 100’ (in cable length) to the MMP and the all the
motors are 5’ from the MMP, then there is 120’ of wire in this application. Refer to the VFD’s
documentation to determine what are acceptable distances before any additional filtering is
To size the VFD properly, simply add the FLA of all attached motors and select a VFD with a higher output FLA.
The branch circuit protection and distribution is typically done with Manual Motor Protectors (MMPS). As seen below, they are the distribution method to each individual motor. This allows for individual motors to be turned off while the rest of the motors operate.