How to isolate the communication ground and power ground of an industrial servo system?

In servo systems, the communication interface ground (e.g., RS485, EtherCAT GND) and power ground (PE) must be isolated to prevent power-side noise from disrupting communication or causing common-mode voltage exceedances. Etymotic isolation solutions utilize isolated communication modules or interface chips. For example, an isolated RS485 transceiver (e.g., ADM2483) is used, powered by an isolated DC-DC module (e.g., B0505S). An isolation transformer is used between the EtherCAT slave controller and the PHY for signal isolation. Sufficient creepage distance (typically >8mm) should be maintained between the isolation grounds, and a Y capacitor (e.g., 1nF/Y1) should be connected across the isolation strip to provide a discharge path for high-frequency common-mode noise and prevent potential accumulation. The shielding layer of the communication interface should be connected to the communication ground at the device end, and the communication ground should be connected to the chassis/power ground through a single point (usually a resistor or ferrite bead) or capacitor. With proper isolation, the communication interface can withstand power frequency withstand voltages up to 1500Vrms and effectively block power noise.