How to shield the strong electrical coupling interference of the intelligent low-voltage monitoring unit?

Strong electrical coupling interference shielding employs dual isolation of electric and magnetic fields. Electric field shielding: A 0.8mm thick aluminum shielding plate is added between the strong and weak current lines, with single-point grounding. Magnetic field shielding: A high-permeability μ125 magnetic ring is used on the strong current cable, while twisted-pair shielded cables are used for the weak current signal lines. In the circuit, the sampling input uses a CMZ20212A-900T common-mode inductor (90μH) for filtering, combined with ESDULC5V0D9B ultra-low capacitance ESD protection. Power isolation uses a WRB2405S-3W DC-DC module. The PCB layout separates the strong and weak current lines with a spacing greater than 15mm and a grounding guard ring in between. This solution can reduce strong electrical coupling interference by more than 45dB, with a sampling error of less than 0.2%, meeting the IEC 61000-4-3 10V/m radiated immunity test requirements.