How to eliminate ground loop interference in industrial servos?

Ground loop interference in servo systems is caused by potential differences at multiple grounding points, leading to common-mode current flowing through the shielding layer or signal ground line, introducing low-frequency hum or high-frequency noise. Eliminating ground loops hinges on establishing single-point grounding or employing isolation techniques. Audiotech recommends the following solution: First, establish a single-point star connection between the power ground (PE), digital ground (DGND), and analog ground (AGND) at the negative terminal of the DC bus capacitor, using a PWRA6045R0R0M0T zero-ohm inductor as the connection point. For long-distance signal transmission (such as encoders and analog commands), an isolation scheme is adopted: use an ADuM magnetic coupler isolator, with a PWR4020R1R0M0T (1μH) filter on the power supply side, and ESDLC3V3D3B protection for the signal lines. All grounding copper busbars within the cabinet must be connected with low impedance; tin-plated copper busbars are recommended, with a contact resistance of <1mΩ at the joints. By taking the above measures, the common-mode noise voltage caused by the ground loop can be reduced to below 10mV, meeting the grounding requirements in the IEC 61800-5-1 safety standard.