How does the equipotential bonding of a concentrator suppress common mode?

Within the distribution box where the concentrator is installed, potential differences between the equipment's metal casing, cable shielding, and grounding busbar can drive common-mode interference current. Equipotential bonding aims to eliminate these potential differences and is fundamental for suppressing common-mode interference. Using copper busbars or braided straps with a cross-sectional area of at least 16mm², connect the concentrator casing, adjacent equipment casings, cable trays, etc., at close range, and finally connect them all to the grounding busbar. Connecting wires should be short and straight, with a length not exceeding 0.5m, to avoid loops.

All cable shielding entering the concentrator should be connected to the casing at the entrance using 360° crimped shielding terminals or metal cable grounding. The shielding ground of each internal circuit board should also be connected to the same casing grounding point. After equipotential bonding, the power frequency potential difference between all metal components should be less than 1V, and the high-frequency (above 1MHz) impedance should be less than 0.1Ω. This can reduce externally induced common-mode interference voltage by more than 90%, significantly improving the system's surge and EFT immunity.