What type of overload protect should be used when a Variable Speed Drive has multiple motors connected in parallel

Often a VSD will have two or more motors connected in parallel on its output as long as the total Full Load Current of all the motors added together is not greater than the drives Maximum Continuous Current there should be no problems.

A point to take into consideration is the dv / dt that is generated by the capacitance of the cables so it is advisable to fit a motor choke in the drives output when using multiple motors on the drive.

As the drive would have to be set for the full load of the total motor load in the circuit then over load protection should be provided for each motor by fitting an LRD** type thermal overload for each motor and then wired in to the control circuit  as to stop the drive if a motor is overloaded is detected.

It is recommended not to disconnect a motor from the VSD whilst under load as this can regenerate voltages back into the drive damaging the IGBT’s of the unit.