Managing EMI (Interference)

EMI (electro-magnetic interference) is a challenge that has to be overcome by some trial and error. Your mileage may vary. The main source of EMI in this build is the servo motor power cable (the power cable that carries power from the servo drive to the servo motor).

Here are some steps you can follow to manage EMI in your setup:

1. Install an EMI filter on the AC input cable, as described in the TDD Board v2.0 Build Guide.
2. Replace the servo motor power cable with a shielded cable, as described in the TDD Board Build Guide. Ensure that the shield is properly earthed to maximise its effectiveness.
3. Install a ferrite bead around the U, V and W cables (not Earth) of the motor power cable close to connection to the servo drive.
4. Run your signal cables (DB25 cable, micro USB cables) as far as possible from the motor power cable (the main source of EMI).
5. Use high quality micro USB cables for all connections in your rig.
6. Run the steps below for setting up your servo drive correctly. Reference voltage (see Fn007 below) needs to be properly setup once your rig has been wired up and all EMI management parts have been installed.
7. Finally, once all is setup and working, reset your PC's PSU to reestablish its reference voltage. You may experience instability in your PC as it too will be affected by the EMI. To rese the PSU, switch off the PC, unplug everything (including the power cable), press the power button for 15 seconds, plug in the power cable, switch on the PC to check that it starts, switch off, plug everything in again, and switch on.