How can the grounding of the concentrator chassis meet EMC requirements?

Grounding of the concentrator chassis is fundamental for controlling radiation and improving immunity, and must meet the requirements of low impedance, large area, and continuity. The chassis should be made of highly conductive materials (such as galvanized steel sheet), and electrical continuity should be ensured between parts through continuous welding or electromagnetic sealing gaskets, with joint lengths less than λ/20 (less than 5 meters for 30MHz). Dedicated grounding studs should be used for the grounding terminals, connected to the mounting base or grounding busbar via short, wide braided tape (cross-sectional area ≥6mm²), with a target connection impedance <10mΩ.

The shielding ground on the PCB should be connected to the chassis with low impedance through multiple screw holes (screw spacing <λ/10). The grounding terminal of the internal filter capacitor (Y capacitor) should be directly connected to the chassis grounding point. For floating ground systems, the chassis can be connected to the circuit ground via a high-voltage capacitor (e.g., 1nF/2kV) and a discharge resistor in parallel. A well-grounded chassis can provide shielding effectiveness of over 40dB, helping to pass the IEC 61000-4-3 10V/m radiated immunity test.