How to coordinate power line surge filtering with power line carrier PLC?

Power line surge filtering for power line carrier PLCs needs to be designed in conjunction with surge protection devices to form a multi-stage protection and filtering network. The first stage is surge protection, using a 2R600L-8×6 gas discharge tube and a 14D511K varistor in parallel to absorb high-energy surges. The second stage is filtering, deploying a common-mode inductor CML4532A-510T after the surge protector to suppress high-frequency oscillations after the surge. The third stage is fine filtering, using a π-type filter circuit with a power inductor PWR6045R6R8M0T and an X2 safety capacitor (0.47μF). A key point of coordination is impedance matching; the surge protection device should present low impedance when discharging surges, while the filter should present high impedance in the surge frequency band to prevent surge energy from entering subsequent circuits. In terms of layout, the surge protection device should be placed as close as possible to the power line inlet, with the filter immediately following. Through coordinated design, the system can simultaneously meet the IEC61000-4-5 surge test and the EN55032 conducted emission standard.