How to prevent interference in power FTU communication cabling?

Communication cabling for interference immunity requires consideration of transmission medium, shielding, and grounding. RS485 uses shielded twisted-pair cable with a characteristic impedance of 120Ω, and the shield is grounded at a single point. Ethernet uses Cat6 STP cable, with both ends of the shield grounded via metal RJ45 connectors. Communication cables and power cables are routed in separate cable trays with a spacing greater than 300mm, crossing perpendicularly when necessary. On the PCB: the RS485 interface uses a CMZ3225A-510T common-mode inductor and ESDSM712 protection device; the Ethernet interface uses a CMZ2012A-900T common-mode inductor and ESDLC3V3D3B protection. This design achieves a communication bit error rate of less than 10^-6, meeting the IEC 61000-4-3 10V/m radiated immunity and IEC 61000-4-4 4kV EFT test requirements.