How to improve interference immunity in a power line carrier PLC system through grounding?

Improving the immunity of power line carrier PLC systems requires comprehensive optimization of grounding design and protection measures. A hierarchical grounding strategy is adopted: the primary ground is for safety, using a low-impedance path (resistance <0.1Ω) connected to the earth; the secondary ground is for signal ground, isolated from the primary ground by an isolation transformer or optocoupler. In the signal grounding system, a common-mode inductor CML4532A-510T and a TVS diode SMCJ24CA are deployed to suppress transient interference. For radio frequency interference, shielded cables are used, and both ends of the shield are grounded (length <λ/20). The grounding network is optimized by simulating and analyzing the grounding system's response to EFT, surge, and other interferences. In actual testing, IEC61000-4 series immunity tests are performed. The optimized system should pass EFT ±4kV, surge ±2kV, and ESD ±8kV tests. Grounding optimization can improve system immunity by 20dB and significantly improve communication reliability.