Any issues of EMI (or electro magnetic compatibility; EMC) are from long runs of wire between the VFD and motor, keep them less then 6ft/2meters long and you'll have zero issues of upset of any control wires used to remote the start stop speed. The manual has the requirements for the potentiometer (variable resistor) for remote speed control (Kohms and power rating). Just follow the manuals suggestions for the remote wiring.Interesting - - - thanks!
Also NEVER put a switch between the VFD and motor, hard wire that. The reason is if you switch the motor while the VFD is running the motor, huge transient voltages can be created that blow up the transistors in the VFD, and at that point it's toast.
Also VFDs really are intended to be connected to one motor. They protect the motor from overload as that's a programable parameter in them, i.e. the motor HP and running current typically. So you can buy a much larger VFD, and program the motor size so it won't be overloaded. Running motors at very slow RPMs for long periods, can burn them up, as the internal cooling fan of the motor does not move enough cooling air. Some VFDs have thermistor inputs, or temp switch inputs for this protection if needed. I've never run into that issue, as I don't do continuous production as I'm just a make a part for some project I'm working on as a "fix broken stuff" guy.